The univalent radical OH. Hydroxyl radical is a potent oxidizing agent.
Highly reactive molecules with an unsatisfied electron valence pair. Free radicals are produced in both normal and pathological processes. They are proven or suspected agents of tissue damage in a wide variety of circumstances including radiation, damage from environment chemicals, and aging. Natural and pharmacological prevention of free radical damage is being actively investigated.
Inorganic compounds that contain the OH- group.
Substances that influence the course of a chemical reaction by ready combination with free radicals. Among other effects, this combining activity protects pancreatic islets against damage by cytokines and prevents myocardial and pulmonary perfusion injuries.
A strong oxidizing agent used in aqueous solution as a ripening agent, bleach, and topical anti-infective. It is relatively unstable and solutions deteriorate over time unless stabilized by the addition of acetanilide or similar organic materials.
A technique applicable to the wide variety of substances which exhibit paramagnetism because of the magnetic moments of unpaired electrons. The spectra are useful for detection and identification, for determination of electron structure, for study of interactions between molecules, and for measurement of nuclear spins and moments. (From McGraw-Hill Encyclopedia of Science and Technology, 7th edition) Electron nuclear double resonance (ENDOR) spectroscopy is a variant of the technique which can give enhanced resolution. Electron spin resonance analysis can now be used in vivo, including imaging applications such as MAGNETIC RESONANCE IMAGING.
A method for determining points of contact between interacting proteins or binding sites of proteins to nucleic acids. Protein footprinting utilizes a protein cutting reagent or protease. Protein cleavage is inhibited where the proteins, or nucleic acids and protein, contact each other. After completion of the cutting reaction, the remaining peptide fragments are analyzed by electrophoresis.
Benzoate derivatives substituted by one or more hydroxy groups in any position on the benzene ring.
Highly reactive compounds produced when oxygen is reduced by a single electron. In biological systems, they may be generated during the normal catalytic function of a number of enzymes and during the oxidation of hemoglobin to METHEMOGLOBIN. In living organisms, SUPEROXIDE DISMUTASE protects the cell from the deleterious effects of superoxides.
Natural product isolated from Streptomyces pilosus. It forms iron complexes and is used as a chelating agent, particularly in the mesylate form.
A fungistatic compound that is widely used as a food preservative. It is conjugated to GLYCINE in the liver and excreted as hippuric acid.
A chemical reaction in which an electron is transferred from one molecule to another. The electron-donating molecule is the reducing agent or reductant; the electron-accepting molecule is the oxidizing agent or oxidant. Reducing and oxidizing agents function as conjugate reductant-oxidant pairs or redox pairs (Lehninger, Principles of Biochemistry, 1982, p471).
A photographic fixative used also in the manufacture of resins. According to the Fourth Annual Report on Carcinogens (NTP 85-002, 1985), this substance may reasonably be anticipated to be a carcinogen (Merck Index, 9th ed). Many of its derivatives are ANTITHYROID AGENTS and/or FREE RADICAL SCAVENGERS.
An iron-molybdenum flavoprotein containing FLAVIN-ADENINE DINUCLEOTIDE that oxidizes hypoxanthine, some other purines and pterins, and aldehydes. Deficiency of the enzyme, an autosomal recessive trait, causes xanthinuria.
An oxidoreductase that catalyzes the conversion of HYDROGEN PEROXIDE to water and oxygen. It is present in many animal cells. A deficiency of this enzyme results in ACATALASIA.
Inorganic or organic compounds that contain divalent iron.
An oxidoreductase that catalyzes the reaction between superoxide anions and hydrogen to yield molecular oxygen and hydrogen peroxide. The enzyme protects the cell against dangerous levels of superoxide. EC 1.15.1.1.
Heterocyclic compounds in which an oxygen is attached to a cyclic nitrogen.
A metallic element with atomic symbol Fe, atomic number 26, and atomic weight 55.85. It is an essential constituent of HEMOGLOBINS; CYTOCHROMES; and IRON-BINDING PROTEINS. It plays a role in cellular redox reactions and in the transport of OXYGEN.
Naturally occurring or synthetic substances that inhibit or retard the oxidation of a substance to which it is added. They counteract the harmful and damaging effects of oxidation in animal tissues.
A highly polar organic liquid, that is used widely as a chemical solvent. Because of its ability to penetrate biological membranes, it is used as a vehicle for topical application of pharmaceuticals. It is also used to protect tissue during CRYOPRESERVATION. Dimethyl sulfoxide shows a range of pharmacological activity including analgesia and anti-inflammation.
Salts and esters of gentisic acid.
Molecules which contain an atom or a group of atoms exhibiting an unpaired electron spin that can be detected by electron spin resonance spectroscopy and can be bonded to another molecule. (McGraw-Hill Dictionary of Chemical and Technical Terms, 4th ed)
Molecules or ions formed by the incomplete one-electron reduction of oxygen. These reactive oxygen intermediates include SINGLET OXYGEN; SUPEROXIDES; PEROXIDES; HYDROXYL RADICAL; and HYPOCHLOROUS ACID. They contribute to the microbicidal activity of PHAGOCYTES, regulation of signal transduction and gene expression, and the oxidative damage to NUCLEIC ACIDS; PROTEINS; and LIPIDS.
A diuretic and renal diagnostic aid related to sorbitol. It has little significant energy value as it is largely eliminated from the body before any metabolism can take place. It can be used to treat oliguria associated with kidney failure or other manifestations of inadequate renal function and has been used for determination of glomerular filtration rate. Mannitol is also commonly used as a research tool in cell biological studies, usually to control osmolarity.
Inorganic or organic compounds containing trivalent iron.
An oxyacid of chlorine (HClO) containing monovalent chlorine that acts as an oxidizing or reducing agent.
A technique for detecting short-lived reactive FREE RADICALS in biological systems by providing a nitrone or nitrose compound for an addition reaction to occur which produces an ELECTRON SPIN RESONANCE SPECTROSCOPY-detectable aminoxyl radical. In spin trapping, the compound trapping the radical is called the spin trap and the addition product of the radical is identified as the spin adduct. (Free Rad Res Comm 1990;9(3-6):163)
An element with atomic symbol O, atomic number 8, and atomic weight [15.99903; 15.99977]. It is the most abundant element on earth and essential for respiration.
Organic chemicals that form two or more coordination links with an iron ion. Once coordination has occurred, the complex formed is called a chelate. The iron-binding porphyrin group of hemoglobin is an example of a metal chelate found in biological systems.
Use of a pulse of X-rays or fast electrons to generate free radicals for spectroscopic examination.
Electron-accepting molecules in chemical reactions in which electrons are transferred from one molecule to another (OXIDATION-REDUCTION).
Inorganic oxides that contain nitrogen.
Peroxidase catalyzed oxidation of lipids using hydrogen peroxide as an electron acceptor.
Placing of a hydroxyl group on a compound in a position where one did not exist before. (Stedman, 26th ed)
A chelating agent that sequesters a variety of polyvalent cations such as CALCIUM. It is used in pharmaceutical manufacturing and as a food additive.
A heavy metal trace element with the atomic symbol Cu, atomic number 29, and atomic weight 63.55.
A disturbance in the prooxidant-antioxidant balance in favor of the former, leading to potential damage. Indicators of oxidative stress include damaged DNA bases, protein oxidation products, and lipid peroxidation products (Sies, Oxidative Stress, 1991, pxv-xvi).
A reagent used for the determination of iron.
A six carbon compound related to glucose. It is found naturally in citrus fruits and many vegetables. Ascorbic acid is an essential nutrient in human diets, and necessary to maintain connective tissue and bone. Its biologically active form, vitamin C, functions as a reducing agent and coenzyme in several metabolic pathways. Vitamin C is considered an antioxidant.
The salts or esters of salicylic acids, or salicylate esters of an organic acid. Some of these have analgesic, antipyretic, and anti-inflammatory activities by inhibiting prostaglandin synthesis.
Peroxides produced in the presence of a free radical by the oxidation of unsaturated fatty acids in the cell in the presence of molecular oxygen. The formation of lipid peroxides results in the destruction of the original lipid leading to the loss of integrity of the membranes. They therefore cause a variety of toxic effects in vivo and their formation is considered a pathological process in biological systems. Their formation can be inhibited by antioxidants, such as vitamin E, structural separation or low oxygen tension.
A purine base found in most body tissues and fluids, certain plants, and some urinary calculi. It is an intermediate in the degradation of adenosine monophosphate to uric acid, being formed by oxidation of hypoxanthine. The methylated xanthine compounds caffeine, theobromine, and theophylline and their derivatives are used in medicine for their bronchodilator effects. (Dorland, 28th ed)
The rate dynamics in chemical or physical systems.
An excited state of molecular oxygen generated photochemically or chemically. Singlet oxygen reacts with a variety of biological molecules such as NUCLEIC ACIDS; PROTEINS; and LIPIDS; causing oxidative damages.
Injuries to DNA that introduce deviations from its normal, intact structure and which may, if left unrepaired, result in a MUTATION or a block of DNA REPLICATION. These deviations may be caused by physical or chemical agents and occur by natural or unnatural, introduced circumstances. They include the introduction of illegitimate bases during replication or by deamination or other modification of bases; the loss of a base from the DNA backbone leaving an abasic site; single-strand breaks; double strand breaks; and intrastrand (PYRIMIDINE DIMERS) or interstrand crosslinking. Damage can often be repaired (DNA REPAIR). If the damage is extensive, it can induce APOPTOSIS.
The location of the atoms, groups or ions relative to one another in a molecule, as well as the number, type and location of covalent bonds.
Chemicals that bind to and remove ions from solutions. Many chelating agents function through the formation of COORDINATION COMPLEXES with METALS.
Derivatives of BENZOIC ACID. Included under this heading are a broad variety of acid forms, salts, esters, and amides that contain the carboxybenzene structure.
A nucleoside consisting of the base guanine and the sugar deoxyribose.
The spatial arrangement of the atoms of a nucleic acid or polynucleotide that results in its characteristic 3-dimensional shape.
A group of compounds that contain a bivalent O-O group, i.e., the oxygen atoms are univalent. They can either be inorganic or organic in nature. Such compounds release atomic (nascent) oxygen readily. Thus they are strong oxidizing agents and fire hazards when in contact with combustible materials, especially under high-temperature conditions. The chief industrial uses of peroxides are as oxidizing agents, bleaching agents, and initiators of polymerization. (From Hawley's Condensed Chemical Dictionary, 11th ed)
A trihydroxybenzene or dihydroxy phenol that can be prepared by heating GALLIC ACID.
Concentrated pharmaceutical preparations of plants obtained by removing active constituents with a suitable solvent, which is evaporated away, and adjusting the residue to a prescribed standard.
Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures.
Benzene derivatives that include one or more hydroxyl groups attached to the ring structure.
A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine).
Liquid chromatographic techniques which feature high inlet pressures, high sensitivity, and high speed.
Removal of ENVIRONMENTAL POLLUTANTS or contaminants for the general protection of the environment. This is accomplished by various chemical, biological, and bulk movement methods, in conjunction with ENVIRONMENTAL MONITORING.
Complete or partial surgical removal of the prostate. Three primary approaches are commonly employed: suprapubic - removal through an incision above the pubis and through the urinary bladder; retropubic - as for suprapubic but without entering the urinary bladder; and transurethral (TRANSURETHRAL RESECTION OF PROSTATE).
A tripeptide with many roles in cells. It conjugates to drugs to make them more soluble for excretion, is a cofactor for some enzymes, is involved in protein disulfide bond rearrangement and reduces peroxides.
The parts of a macromolecule that directly participate in its specific combination with another molecule.
Urea compounds which are substituted with one or more methyl groups.
A hemeprotein from leukocytes. Deficiency of this enzyme leads to a hereditary disorder coupled with disseminated moniliasis. It catalyzes the conversion of a donor and peroxide to an oxidized donor and water. EC 1.11.1.7.
A method for determining the sequence specificity of DNA-binding proteins. DNA footprinting utilizes a DNA damaging agent (either a chemical reagent or a nuclease) which cleaves DNA at every base pair. DNA cleavage is inhibited where the ligand binds to DNA. (from Rieger et al., Glossary of Genetics: Classical and Molecular, 5th ed)
A genus of basidiomycetous mushroom in the family Strophariaceae, exhibiting a bipolar mating system.
Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.
Techniques used for determining the values of photometric parameters of light resulting from LUMINESCENCE.
An iron chelating agent with properties like EDETIC ACID. DTPA has also been used as a chelator for other metals, such as plutonium.
Chemical bond cleavage reactions resulting from absorption of radiant energy.
The facilitation of a chemical reaction by material (catalyst) that is not consumed by the reaction.
Theoretical representations that simulate the behavior or activity of chemical processes or phenomena; includes the use of mathematical equations, computers, and other electronic equipment.
The dialdehyde of malonic acid.
A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.
Destruction by passage of a galvanic electric current, as in disintegration of a chemical compound in solution.
A purine and a reaction intermediate in the metabolism of adenosine and in the formation of nucleic acids by the salvage pathway.
Low-molecular-weight end products, probably malondialdehyde, that are formed during the decomposition of lipid peroxidation products. These compounds react with thiobarbituric acid to form a fluorescent red adduct.
Inorganic or organic salts and esters of nitric acid. These compounds contain the NO3- radical.
A plant genus of the family CUCURBITACEAE known for the edible fruit.
An iron-binding protein that was originally characterized as a milk protein. It is widely distributed in secretory fluids and is found in the neutrophilic granules of LEUKOCYTES. The N-terminal part of lactoferrin possesses a serine protease which functions to inactivate the TYPE III SECRETION SYSTEM used by bacteria to export virulence proteins for host cell invasion.
Granular leukocytes having a nucleus with three to five lobes connected by slender threads of chromatin, and cytoplasm containing fine inconspicuous granules and stainable by neutral dyes.
An analytical method used in determining the identity of a chemical based on its mass using mass analyzers/mass spectrometers.
Inorganic or organic oxy acids of sulfur which contain the RSO2(OH) radical.
Purine bases related to hypoxanthine, an intermediate product of uric acid synthesis and a breakdown product of adenine catabolism.
The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.
Compounds that increase urine volume by increasing the amount of osmotically active solute in the urine. Osmotic diuretics also increase the osmolarity of plasma.
Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.
Sulfhydryl acylated derivative of GLYCINE.
An inhibitor of DOPA DECARBOXYLASE that does not enter the central nervous system. It is often given with LEVODOPA in the treatment of parkinsonism to prevent the conversion of levodopa to dopamine in the periphery, thereby increasing the amount that reaches the central nervous system and reducing the required dose. It has no antiparkinson actions when given alone.
A group of 1,2-benzenediols that contain the general formula R-C6H5O2.
The relationship between the chemical structure of a compound and its biological or pharmacological activity. Compounds are often classed together because they have structural characteristics in common including shape, size, stereochemical arrangement, and distribution of functional groups.
An enzyme of the oxidoreductase class that catalyzes the conversion of beta-D-glucose and oxygen to D-glucono-1,5-lactone and peroxide. It is a flavoprotein, highly specific for beta-D-glucose. The enzyme is produced by Penicillium notatum and other fungi and has antibacterial activity in the presence of glucose and oxygen. It is used to estimate glucose concentration in blood or urine samples through the formation of colored dyes by the hydrogen peroxide produced in the reaction. (From Enzyme Nomenclature, 1992) EC 1.1.3.4.
A non-essential amino acid. In animals it is synthesized from PHENYLALANINE. It is also the precursor of EPINEPHRINE; THYROID HORMONES; and melanin.
A poisonous dipyridilium compound used as contact herbicide. Contact with concentrated solutions causes irritation of the skin, cracking and shedding of the nails, and delayed healing of cuts and wounds.
A basic science concerned with the composition, structure, and properties of matter; and the reactions that occur between substances and the associated energy exchange.
Compounds in which one or more of the ketone groups on the pyrimidine ring of barbituric acid are replaced by thione groups.
Polyacenes with four ortho-fused benzene rings in a straight linear arrangement. This group is best known for the subclass called TETRACYCLINES.
Devices for accelerating protons or electrons in closed orbits where the accelerating voltage and magnetic field strength varies (the accelerating voltage is held constant for electrons) in order to keep the orbit radius constant.
A morpholinyl sydnone imine ethyl ester, having a nitrogen in place of the keto oxygen. It acts as NITRIC OXIDE DONORS and is a vasodilator that has been used in ANGINA PECTORIS.
Organic compounds containing a carbonyl group in the form -CHO.
Elements of limited time intervals, contributing to particular results or situations.
The composition, conformation, and properties of atoms and molecules, and their reaction and interaction processes.

Role of iron in Nramp1-mediated inhibition of mycobacterial growth. (1/1306)

Innate resistance to mycobacterial growth is mediated by a gene, Nramp1. We have previously reported that Nramp1 mRNA from macrophages of Mycobacterium bovis BCG-resistant (Bcgr) mice is more stable than Nramp1 mRNA from macrophages of BCG-susceptible (Bcgs) mice. Based on these observations and on reports that show that the closely related Nramp2 gene is a metal ion transporter, we evaluated the effect of iron on the growth of Mycobacterium avium within macrophages as well as on the stability of Nramp1 mRNA. The addition of iron to macrophages from Bcgs mice resulted in a stimulation of mycobacterial growth. In contrast, iron increased the capacity of macrophages from Bcgr mice to control the growth of M. avium. When we treated recombinant gamma interferon (IFN-gamma)-activated macrophages with iron, we found that iron abrogated the growth inhibitory effect of IFN-gamma-activated macrophages from Bcgs mice but that it did not affect the capacity of macrophages from Bcgr mice to control microbial growth. A more detailed examination of the effect of iron on microbial growth showed that the addition of small quantities of iron to resident macrophages from Bcgr mice stimulated antimicrobial activity within a very narrow dose range. The effect of iron on the growth inhibitory activity of macrophages from Bcgr mice was abrogated by the addition of catalase or mannitol to the culture medium. These results are consistent with an Fe(II)-mediated stimulation of the Fenton/Haber-Weiss reaction and hydroxyl radical-mediated inhibition of mycobacterial growth.  (+info)

EPR spin trapping and 2-deoxyribose degradation studies of the effect of pyridoxal isonicotinoyl hydrazone (PIH) on *OH formation by the Fenton reaction. (2/1306)

The search for effective iron chelating agents was primarily driven by the need to treat iron-loading refractory anemias such as beta-thalassemia major. However, there is a potential for therapeutic use of iron chelators in non-iron overload conditions. Iron can, under appropriate conditions, catalyze the production of toxic oxygen radicals which have been implicated in numerous pathologies and, hence, iron chelators may be useful as inhibitors of free radical-mediated tissue damage. We have developed the orally effective iron chelator pyridoxal isonicotinoyl hydrazone (PIH) and demonstrated that it inhibits iron-mediated oxyradical formation and their effects (e.g. 2-deoxyribose oxidative degradation, lipid peroxidation and plasmid DNA breaks). In this study we further characterized the mechanism of the antioxidant action of PIH and some of its analogs against *OH formation from the Fenton reaction. Using electron paramagnetic resonance (EPR) with 5, 5-dimethyl-1-pyrroline-N-oxide (DMPO) as a spin trap for *OH we showed that PIH and salicylaldehyde isonicotinoyl hydrazone (SIH) inhibited Fe(II)-dependent production of *OH from H2O2. Moreover, PIH protected 2-deoxyribose against oxidative degradation induced by Fe(II) and H2O2. The protective effect of PIH against both DMPO hydroxylation and 2-deoxyribose degradation was inversely proportional to Fe(II) concentration. However, PIH did not change the primary products of the Fenton reaction as indicated by EPR experiments on *OH-mediated ethanol radical formation. Furthermore, PIH dramatically enhanced the rate of Fe(II) oxidation to Fe(III) in the presence of oxygen, suggesting that PIH decreases the concentration of Fe(II) available for the Fenton reaction. These results suggest that PIH and SIH deserve further investigation as inhibitors of free-radical mediated tissue damage.  (+info)

Increased methamphetamine neurotoxicity in heterozygous vesicular monoamine transporter 2 knock-out mice. (3/1306)

Methamphetamine (METH) is a powerful psychostimulant that is increasingly abused worldwide. Although it is commonly accepted that the dopaminergic system and oxidation of dopamine (DA) play pivotal roles in the neurotoxicity produced by this phenylethylamine, the primary source of DA responsible for this effect has remained elusive. In this study, we used mice heterozygous for vesicular monoamine transporter 2 (VMAT2 +/- mice) to determine whether impaired vesicular function alters the effects of METH. METH-induced dopaminergic neurotoxicity was increased in striatum of VMAT2 +/- mice compared with wild-type mice as revealed by a more consistent DA and metabolite depletion and a greater decrease in dopamine transporter expression. Interestingly, increased METH neurotoxicity in VMAT2 +/- mice was accompanied by less pronounced increase in extracellular DA and indices of free radical formation compared with wild-type mice. These results indicate that disruption of vesicular monoamine transport potentiates METH-induced neurotoxicity in vivo and point, albeit indirectly, to a greater contribution of intraneuronal DA redistribution rather than extraneuronal overflow on mediating this effect.  (+info)

Release of copper ions from the familial amyotrophic lateral sclerosis-associated Cu,Zn-superoxide dismutase mutants. (4/1306)

Point mutations of Cu,Zn-superoxide dismutase (SOD) have been linked to familial amyotrophic lateral sclerosis (FALS). We reported that the Swedish FALS Cu,Zn-SOD mutant, D90A, exhibited an enhanced hydroxyl radical-generating activity, while its dismutation activity was identical to that of the wild-type enzyme (Kim et al. 1998a; 1998b). Transgenic mice that express a mutant Cu,Zn-SOD, Gly93 --> Ala (G93A), have been shown to develop amyotrophic lateral sclerosis (ALS) symptoms. We cloned the cDNA for the FALS G93A mutant, overexpressed the protein in E. coli cells, purified the protein, and studied its enzymic activities. Our results showed that the G93A, the D90A, and the wild-type enzymes have identical dismutation activity. However, the hydroxyl radical-generating activity of the G93A mutant was enhanced relative to those of the D90A and the wild-type enzyme (wild-type < D90A < G93A). These higher free radical-generating activities of mutants facilitated the release of copper ions from their own molecules (wild-type < D90A < G93A). The released copper ions can enhance the Fenton-like reaction to produce hydroxyl radicals and play a major role in the oxidative damage of macromolecules. Thus, the FALS symptoms may be associated with the enhancements in both the free radical-generating activity and the releasing of copper ions from the mutant enzyme.  (+info)

Hydroxyl-radical production in physiological reactions. A novel function of peroxidase. (5/1306)

Peroxidases catalyze the dehydrogenation by hydrogen peroxide (H2O2) of various phenolic and endiolic substrates in a peroxidatic reaction cycle. In addition, these enzymes exhibit an oxidase activity mediating the reduction of O2 to superoxide (O2.-) and H2O2 by substrates such as NADH or dihydroxyfumarate. Here we show that horseradish peroxidase can also catalyze a third type of reaction that results in the production of hydroxyl radicals (.OH) from H2O2 in the presence of O2.-. We provide evidence that to mediate this reaction, the ferric form of horseradish peroxidase must be converted by O2.- into the perferryl form (Compound III), in which the haem iron can assume the ferrous state. It is concluded that the ferric/perferryl peroxidase couple constitutes an effective biochemical catalyst for the production of .OH from O2.- and H2O2 (iron-catalyzed Haber-Weiss reaction). This reaction can be measured either by the hydroxylation of benzoate or the degradation of deoxyribose. O2.- and H2O2 can be produced by the oxidase reaction of horseradish peroxidase in the presence of NADH. The .OH-producing activity of horseradish peroxidase can be inhibited by inactivators of haem iron or by various O2.- and .OH scavengers. On an equimolar Fe basis, horseradish peroxidase is 1-2 orders of magnitude more active than Fe-EDTA, an inorganic catalyst of the Haber-Weiss reaction. Particularly high .OH-producing activity was found in the alkaline horseradish peroxidase isoforms and in a ligninase-type fungal peroxidase, whereas lactoperoxidase and soybean peroxidase were less active, and myeloperoxidase was inactive. Operating in the .OH-producing mode, peroxidases may be responsible for numerous destructive and toxic effects of activated oxygen reported previously.  (+info)

Cytosolic Ca2+ movements of endothelial cells exposed to reactive oxygen intermediates: role of hydroxyl radical-mediated redox alteration of cell-membrane Ca2+ channels. (6/1306)

1. The mode of action of reactive oxygen intermediates in cysosolic Ca2+ movements of cultured porcine aortic endothelial cells exposed to xanthine/xanthine oxidase (X/XO) was investigated. 2. Cytosolic Ca2+ movements provoked by X/XO consisted of an initial Ca2+ release from thapsigargin-sensitive intracellular Ca2+ stores and a sustained Ca2+ influx through cell-membrane Ca2+ channels. The Ca2+ movements from both sources were inhibited by catalase, cell-membrane permeable iron chelators (o-phenanthroline and deferoxamine), a *OH scavenger (5,5-dimethyl-1-pyrroline-N-oxide), or an anion channel blocker (disodium 4, 4'-diisothiocyano-2, 2'-stilbenedisulphonic acid), suggesting that *O2- influx through anion channels was responsible for the Ca2+ movements, in which *OH generation catalyzed by intracellular transition metals (i.e., Haber-Weiss cycle) was involved. 3. After an initial Ca2+ elevation provoked by X/XO, cytosolic Ca2+ concentration decreased to a level higher than basal levels. Removal of X/XO slightly enhanced the Ca2+ decrease. Extracellular addition of sulphydryl (SH)-reducing agents, dithiothreitol or glutathione, after the removal of X/XO accelerated the decrement. A Ca2+ channel blocker, Ni2+, abolished the sustained increase in Ca2+, suggesting that Ca2+ influx through cell-membrane Ca2+ channels was extracellularly regulated by the redox state of SH-groups. 4. The X/XO-provoked change in cellular respiration was inhibited by Ni2+ or dithiothreitol as well as inhibitors of Haber-Weiss cycle, suggesting that Ca2+ influx was responsible for *OH-mediated cytotoxicity. We concluded that intracellular *OH generation was involved in the Ca2+ movements in endothelial cells exposed to X/XO. Cytosolic Ca2+ elevation was partly responsible for the oxidants-mediated cytotoxicity.  (+info)

Directional binding of HMG-I(Y) on four-way junction DNA and the molecular basis for competitive binding with HMG-1 and histone H1. (7/1306)

Histone H1, HMG-1 and HMG-I(Y) are mammalian nuclear proteins possessing distinctive DNA-binding domain structures that share the common property of preferentially binding to four-way junction (4H) DNA, an in vitro mimic of the in vivo genetic recombination intermediate known as the Holliday junction. Nevertheless, these three proteins bind to 4H DNA in vitro with very different affinities and in a mutually exclusive manner. To investigate the molecular basis for these distinctive binding characteristics, we employed base pair resolution hydroxyl radical footprinting to determine the precise sites of nucleotide interactions of both HMG-1 and histone H1 on 4H DNA and compared these contacts with those previously described for HMG-I(Y) on the same substrate. Each of these proteins had a unique binding pattern on 4H DNA and yet shared certain common nucleotide contacts on the arms of the 4H DNA molecule near the branch point. Both the HMG-I(Y) and HMG-1 proteins made specific contacts across the 4H DNA branch point, as well as interacting at discrete sites on the arms, whereas the globular domain of histone H1 bound exclusively to the arms of the 4H DNA substrate without contacting nucleotides at the crossover region. Experiments employing the chemical cleavage reagent 1, 10-orthophenanthroline copper(II) attached to the C-terminal end of a site-specifically mutagenized HMG-I(Y) protein molecule demonstrated that this protein binds to 4H DNA in a distinctly polar, direction-specific manner. Together these results provide an attractive molecular explanation for the observed mutually exclusive 4H DNA-binding characteristics of these proteins and also allow for critical assessment of proposed models for their interaction with 4H DNA substrates. The results also have important implications concerning the possible in vivo roles of HMG-I(Y), histone H1 and HMG-1 in biological processes such as genetic recombination and retroviral integration.  (+info)

Vanadate-induced activation of activator protein-1: role of reactive oxygen species. (8/1306)

The present study was undertaken to test the hypothesis that the toxicity and carcinogenicity of vanadium might arise from elevation of reactive oxygen species leading to activation of the transcription factor activator protein-1 (AP-1). The AP-1 transactivation response has been implicated as causal in transformation responses to phorbol esters and growth factors. To investigate the possible activity of vanadium in the activation of AP-1, we treated mouse epidermal JB6 P+ cells stably transfected with an AP-1 luciferase reporter plasmid with various concentrations of vanadate. This resulted in concentration-dependent transactivation of AP-1. Superoxide dismutase (SOD) and catalase inhibited AP-1 activation induced by vanadate, indicating the involvement of superoxide anion radical (O2-*), hydroxyl radical (*OH) and/or H2O2 in the mechanism of vanadate-induced AP-1 activation. However, sodium formate, a specific *OH scavenger, did not alter vanadate-induced AP-1 activation, suggesting a minimal role for the *OH radical. NADPH enhanced AP-1 activation by increasing vanadate-mediated generation of O2-*. N-acetylcysteine, a thiol-containing antioxidant, decreased activation, further showing that vanadate-induced AP-1 activation involved redox reactions. Calphostin C, a specific inhibitor of protein kinase C (PKC), inhibited activation of AP-1, demonstrating that PKC is involved in the cell signal cascades leading to vanadate-induced AP-1 activation. Electron spin resonance (ESR) measurements show that JB6 P+ cells are able to reduce vanadate to generate vanadium(IV) in the presence of NADPH. Molecular oxygen was consumed during the vanadate reduction process to generate O2-* as measured by ESR spin trapping using 5,5-dimethyl-L-pyrroline N-oxide as the spin trapping agent. SOD inhibited the ESR spin adduct signal, further demonstrating the generation of O2-* in the cellular reduction of vanadate. These results provide support for a model in which vanadium, like other classes of tumor promoters, transactivates AP-1-dependent gene expression. In the case of vanadium, AP-1 transactivation is dependent on the generation of O2-* and H2O2, but not *OH.  (+info)

TY - JOUR. T1 - Endogenous superoxide dismutase levels regulate iron-dependent hydroxyl radical formation in Escherichia coli exposed to hydrogen peroxide. AU - Mccormick, Michael L.. AU - Buettner, Garry R.. AU - Britigan, Bradley E.. PY - 1998/2/1. Y1 - 1998/2/1. N2 - Aerobic organisms contain antioxidant enzymes, such as superoxide dismutase (SOD) and catalase, to protect them from both direct and indirect effects of reactive oxygen species, such as O2- and H2O2. Previous work by others has shown that Escherichia coli mutants lacking SOD not only are more susceptible to DNA damage and killing by H2O2 but also contain larger pools of intracellular free iron. The present study investigated if SOD- deficient E. coli cells are exposed to increased levels of hydroxyl radical (OH) as a consequence of the reaction of H2O2 with this increased iron pool. When the parental E. coli strain AB1157 was exposed to H2O2 in the presence of an α-(4-pyridyl-1-oxide)-N-tert-butyl-nitrone (4-POBN)-ethanol ...
The universally conserved eukaryotic initiation factor (eIF), eIF1A, plays multiple roles throughout initiation: it stimulates eIF2/GTP/Met-tRNAiMet attachment to 40S ribosomal subunits, scanning, start codon selection and subunit joining. Its bacterial ortholog IF1 consists of an oligonucleotide/oligosaccharide-binding (OB) domain, whereas eIF1A additionally contains a helical subdomain, N-terminal tail (NTT) and C-terminal tail (CTT). The NTT and CTT both enhance ribosomal recruitment of eIF2/GTP/Met-tRNAiMet, but have opposite effects on the stringency of start codon selection: the CTT increases, whereas the NTT decreases it. Here, we determined the position of eIF1A on the 40S subunit by directed hydroxyl radical cleavage. eIF1As OB domain binds in the A site, similar to IF1, whereas the helical subdomain contacts the head, forming a bridge over the mRNA channel. The NTT and CTT both thread under Met-tRNAiMet reaching into the P-site. The NTT threads closer to the mRNA channel. In the ...
TY - JOUR. T1 - Spin trapping evidence for myeloperoxidase-dependent hydroxyl radical formation by human neutrophils and monocytes. AU - Ramos, C. L.. AU - Pou, S.. AU - Britigan, B. E.. AU - Cohen, M. S.. AU - Rosen, G. M.. PY - 1992/1/1. Y1 - 1992/1/1. N2 - Using the electron spin resonance/spin trapping system, 4-pyridyl 1-oxide N-tert-butylnitrone (4-POBN)/ethanol, hydroxyl radical was detected as the α-hydroxyethyl spin trapped adduct of 4-POBN, 4-POBN-CH(CH3)OH, from phorbol 12-myristate 13-acetate-stimulated human neutrophils and monocytes without the addition of supplemental iron. 4-POBN-CH(CH3)OH was stable in the presence of a neutrophil-derived superoxide flux. Hydroxyl radical formation was inhibited by treatment with superoxide dismutase, catalase, and azide. Treatment with a series of transition metal chelators did not appreciably alter 4-POBN-CH(CH3)OH, which suggested that hydroxyl radical generation was mediated by a mechanism independent of the transition metal- catalyzed ...
In the study, Folium Sennae (FS) was firstly extracted by various solvents to obtain five FS extracts. Then, five FS extracts were evaluated for the protective effects against •OH-induced DNA damage, antioxidant abilities in vitro, and chemical contents using various methods. On this basis, the correlation graphs between the pharmacological effects and chemical contents were plotted to obtain the correlation coefficients (R values). Finally, in order to obtain biological evidence, ethyl acetate extract of FS (EAFS) was investigated for the protective effect against •OH-induced MSCs (mesenchymal stem cells) damage using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl) assay. The pharmacological assays indicated that five FS extracts could effectively protect against •OH-induced DNA damage. The correlation analysis suggested that the average R values of total phenolics, total anthraquinones, aloe-emodin, rhein, and emodin were respectively 0.843, 0.833, 0.753, 0.820, and 0.784, while those of total
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Pyrite-induced hydroxyl radical formation and its effect on nucleic acids. . Biblioteca virtual para leer y descargar libros, documentos, trabajos y tesis universitarias en PDF. Material universiario, documentación y tareas realizadas por universitarios en nuestra biblioteca. Para descargar gratis y para leer online.
The homogeneous decomposition of hydrogen peroxide has been used as a source of hydroxyl radicals. In part I values were reported for the relative rates of reaction of hydroxyl radicals with methane, carbon monoxide, formaldehyde and hydrogen peroxide. In this paper these values are confirmed for different experimental conditions and more consideration is given to details of subsequent reactions. The reaction of methyl radicals with oxygen has previously been shown to occur by a third order reaction both at 200 °C (Hoare & Walsh 1957) and at room temperature (Christie 1958). Present results show that the reaction is second order at 525 °C as suggested by Barnard & Honeyman (1964). In the absence of added oxygen, methyl radicals combine to give ethane which in turn reacts with hydroxyl radicals twelve times more rapidly than does methane. ...
Osaka, Japan - Panasonic Corporation today announced that, in collaboration with Mayo Yasugi, Associate Professor, Department of Veterinary Science, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, it has verified the inhibitory effect of the hydroxyl radicals contained in water (nano-sized electrostatic atomized water particle) on the novel coronavirus (SARS-CoV-2).. Hydroxyl radicals contained in water are particulate ions containing hydroxyl radicals that are generated by applying a high voltage to moisture in the air. They are characterized by being strongly oxidative and highly reactive. Panasonic has been conducting research on this technology over the past 20 years since 1997, and has verified its effectiveness in a variety of areas, including inhibiting pathogenic microorganism (bacteria, fungi, and viruses) and allergens, breaking down PM 2.5 components that have adverse effects on the human body*1.. In 2012, Panasonic conducted a virus clearance test ...
We have constructed a database of hydroxyl radical (•OH) cleavage patterns of DNA in order to investigate the relationship between the sequence of a DNA molecule and its three-dimensional structure. The hydroxyl radical cuts DNA at every nucleotide, with the amount of cutting proportional to the solvent accessible surface area (SASA) of the deoxyribose hydrogen atoms. Cleavage fragments are quantified by a fluorescence sequencer, followed by normalization and deposition into the database. Our database currently contains 151 DNA sequences with lengths ranging from 35 to 41 nucleotides. These data have enabled us to develop some general rules regarding the sequence-dependence of DNA structure as well as to predict the cleavage pattern of any given DNA sequence with remarkable precision. Using this prediction algorithm, it is possible to construct structural maps of entire genomes. As there are many examples of DNA binding proteins with highly degenerate binding sites, the use of structural ...
1EMI: The location of protein S8 and surrounding elements of 16S rRNA in the 70S ribosome from combined use of directed hydroxyl radical probing and X-ray crystallography.
Superoxide dismutase reduces injury in many disease processes, implicating superoxide anion radical (O2-.) as a toxic species in vivo. A critical target of superoxide may be nitric oxide (NO.) produced by endothelium, macrophages, neutrophils, and brain synaptosomes. Superoxide and NO. are known to …
Chemical and enzymatic probing methods are powerful techniques for examining details of sequence-dependent structure in DNA and RNA. Reagents that cleave nucleic acid molecules in a structure-specific, but relatively sequence-non-specific manner, such as hydroxyl radical or DNase I, have been used widely to probe helical geometry in nucleic acid structures, nucleic acid-drug complexes, and in nucleoprotein assemblies. Application of cleavage-based techniques to structures present in superhelical DNA has been hindered by the fact that the cleavage pattern attributable to supercoiling-dependent structures is heavily mixed with non-specific cleavage signals that are inevitable products of multiple cleavage events. We present a rigorous mathematical procedure for extracting the cleavage pattern specific to supercoiled DNA and use this method to investigate the hydroxyl radical cleavage pattern in a cruciform DNA structure formed by a 60 bp inverted repeat sequence embedded in a negatively ...
Our advanced oxidation system uses patented reactor technology to combine ozone and hydrogen peroxide to produce hydroxyl radicals in a plug flow reactor.
It is strongly suggested that although hydrogen peroxide is present in AEW as a source of hydroxyl radicals, the antimicrobial activity of AEW does not depend on these radicals.
BioAssay record AID 1085259 submitted by ChEMBL: Antioxidant activity assessed as hydroxyl radical scavenging activity at 40 uM after 60 min using thiobarbutaric acid by spectrophotometry.
BioAssay record AID 1084363 submitted by ChEMBL: Antioxidant activity assessed as hydroxyl radical scavenging activity at 100 ug/ml after 4 hr.
Free hydroxyl radicals (free ·OH), singlet oxygen (1O2), or ·OH produced by DNA-copper-hydroperoxo complexes are possible DNA-damaging reactive oxygen species (ROS) in the reaction system containing copper, catechol, and DNA. para-Chlorobenzoic acid (pCBA) degradation studies revealed that CuCl2 mixed with catechol produced free ·OH. In the presence of DNA, however, inhibition of the pCBA degradation suggested that another ROS is responsible for the DNA degradation. Of a series of ROS scavengers investigated, only KI, NaN3, and Na-formate-all of the salts tested-strongly inhibited the DNA degradation, suggesting that the ionic strength rather than the reactivity of the individual scavengers could be responsible for the observed inhibition. The ionic strength effect was confirmed by increasing the concentration of phosphate buffer, which is a poor ·OH scavenger, and was interpreted as the result of destabilization of DNA-copper-hydroperoxo complexes. Piperidine-labile site patterns in DNA ...
Buy Cell Meter(TM) Mitochondrial Hydroxyl Radical Detection Kit *Red Fluorescence*, item number: ABD-16055 from AAT Bioquest at Biomol!
Water scarcity and water pollution is a worldwide problem and has driven research into eco-friendly and low-energy cost efficient remediation. The reuse of wastewater for non-potable purpose after proper treatment is the only sustainable solution to the problem. Advanced oxidation processes (AOP) based on the in-situ generation of hydroxyl radicals have been intensively investigated for this purpose as a treatment step to achieve wastewater reuse. The main degradation mechanism of AOPs is based on the reaction of hydroxyl radicals with dissolved organic matter. However, hydroxyl radicals follow unselective multi-step pathways, limiting their efficiency in complex environmental matrices. To overcome such limitations, AOP treatment, based on generation of sulfate radicals, has been developed and widely investigated. This current mini-review will cover the most recent developments regarding emerging contaminant removal, i.e., organic micropollutants, using sulfate radicals generated by active persulfate or
TY - JOUR. T1 - Hydroxyl radical-suppressing mechanism and efficiency of melanin-mimetic nanoparticles. AU - Hayashi, Koichiro. AU - Tokuda, Atsuto. AU - Sakamoto, Wataru. PY - 2018/8/7. Y1 - 2018/8/7. N2 - Harnessing melanins to scavenge free radicals in vivo may yield treatment methods for inflammatory disorders. Furthermore, elucidation of the mechanism underlying melanin-mediated suppression of free radicals, which is yet unclear, is warranted. Herein, we chemically synthesized melanin-mimetic nanoparticles (MeNPs) and investigated the mechanism underlying their use. MeNPs efficiently suppressed hydroxyl radicals by converting some MeNP hydroxyl groups to ketone groups. Furthermore, they suppressed hydroxyl radicals produced by lipopolysaccharide-treated Kupffer cells involved in hepatic cirrhosis pathogenesis, without causing significant cytotoxicity. The present results indicate the suitability of MeNPs to treat hepatic cirrhosis; however, further in vivo studies are warranted to determine ...
During the treatment of cells with anthracyclines, NADPH-dependent flavin reductase reduces the drug to a semiquinone radical, which can donate its free electron to molecular oxygen and generate the superoxide radical (O2 ·). At neutral pH, the main reaction of O2 · is a relatively slow spontaneous dismutation to H2O2 and O2, but this reaction can be accelerated by superoxide dismutase. Superoxide anion and hydrogen peroxide may interact (with metal ions such as iron or copper as catalyst) by the Haber-Weiss reaction to generate hydroxyl radicals (⋅OH). By using electron spin resonance together with a spin-trap such as 5,5-dimethyl pyrroline-N-oxide, anthracycline-induced⋅OH has been detected in several types of cancer cells (for a review, see Sinha and Mimmaugh, 1990). This result suggests that anthracycline-induced free radical production may occur independently of the interaction of the drug with internal membranes or even DNA. Although there is strong evidence that ROS play a role in ...
Transcription is often regulated at the level of initiation by the presence of transcription factors or nucleoid proteins or by changing concentrations of metabolites. These can influence the kinetic properties and/or structures of the intermediate RNA polymerase-DNA complexes in the pathway. Time-resolved footprinting techniques combine the high temporal resolution of a stopped-flow apparatus with the specific structural information obtained by the probing agent. Combined with a careful quantitative analysis of the evolution of the signals, this approach allows for the identification and kinetic and structural characterization of the intermediates in the pathway of DNA sequence recognition by a protein, such as a transcription factor or RNA polymerase. The combination of different probing agents is especially powerful in revealing different aspects of the conformational changes taking place at the protein-DNA interface. For example, hydroxyl radical footprinting, owing to their small size, ...
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The data generated in the POC/O3 experiments indicates that during an actual cleaning event, the concentration of OH produced could increase the background OH concentration of 1.23 105 molecules cm3 (Sarwar, 2002). This increased OH concentration could result in additional VOC/OH chemistry which could further increase the formation of oxygenated organic compounds and impact building occupant
This is the enzymology protocol on Assay of Acid phosphatase enzyme activity from Potatoes. Before going to the protocol, we should know few points about phosphatase enzyme. A phosphatase is an enzyme that removes a phosphate group from its substrate by hydrolyzing phosphoric acid monoesters into a phosphate ion and a molecule with a free hydroxyl group. This action is directly opposite to that of phosphorylases and kinases, which attach phosphate groups to their substrates by using […] ...
A number of systems have evolved to protect cells from reactive oxygen species (peroxides, superoxides, hydroxyl radicals, etc...). This property creates a list of those genes identified as being related to this protective role ...
Been the respiratory system, kidneys, nervous system, metabolism, regulation of medicines are available to help fight highly reactive hydroxyl radicals and other diseases using a fake flash player update. We recommend you consume should be used acutely in patients with joint inflammation, osteoarthritis, rheumatoid, and septic.. ...
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In the hydrothermal crystallization of zeolites from basic media, hydroxide ions (OH-) catalyze the depolymerization of the aluminosilicate gel by breaking the Si,Al-O-Si,Al bonds and catalyze the polymerization of the aluminosilicate anions around the hydrated cation species by remaking the Si,Al-O-Si,Al bonds. We report that hydroxyl free radicals (•OH) are involved in the zeolite crystallization under hydrothermal conditions. The crystallization processes of zeolites-such as Na-A, Na-X, NaZ-21, and silicalite-1-can be accelerated with hydroxyl free radicals generated by ultraviolet irradiation or Fentons reagent. ...
PYSer suppresses iron-induced hydroxyl radical generation and UV-induced wrinkle formation. As the compound forms stable complexes with Fe3þ and inhibits iron-induced hydroxyl radical generation, it is expected to suppress free radical reactions by sequestering the catalytic iron in the body. PYSer has shown a protective effect on photo aging in hairless mice. The mechanism of the photo protection seems to be through the suppression of hydroxyl radical generation, as shown in an in vitro assay (38). An American perspective. Advanced Technology Conference Proceedings. Cosmetics Toiletries 1996; 26:26- 29. 2 Definition Bert Jan Vermeer Leiden University Medical Center, Leiden, The Netherlands References 13 New insights about the function of the skin, as well as the development of new products for skin care, make it necessary to question or redefine the definitions of cosmetics and drugs. Moreover, in the USA, Europe, and Japan, different definitions of cosmetics are used. The definition of a drug ...
In electro-Fenton process, current density is a key operating parameter for organic compound mineralization. In order to explain mineralization yields obtained during the electrochemical treatment of an antibiotic metronidazole (MTZ) in a mono-compartment batch reactor, the evolution of the reactive oxygen species was discussed. Dissolved oxygen, Hydrogen peroxide and hydroxyl radical ((OH)-O-center dot) concentrations were followed during electrolysis performed at current intensities from 50 to 600 mA corresponding to current densities from 0.04 to 0.45 mA cm(-2), using a three dimensional graphite felt as working electrode. Dimethylsulfoxide (DMSO) was used to trap hydroxyl radicals by the production of a stable intermediate, methanesulfonate; however the evolution of hydroxyl radical concentration was not in accordance with MTZ mineralization yields. Results showed that on the one hand, for the highest studied current densities, dissolved oxygen could become a limiting reagent for the (OH)-O-center
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This is probably due the carbonate radical production from hydroxyl radical and bicarbonate with a second order. rate constant of 8.5 × 106 M−1 s− 1 [22] and posterior probe oxidation by both carbonate and hydroxyl radical, as they are not specific MK-2206 solubility dmso [50]. In the case of DHR, hydroxyl radicals are the most reactive but least efficient in generating fluorescent products, probably because of lower selectivity of attack than carbonate radical [50]. In the case of NADH oxidation, the observed higher oxidation when bicarbonate is present probably reside in the fact that hydroxyl radical can either add or oxidize targets, whereas carbonate radical only oxidize the biomolecule, a direct observation derived from their different redox potential and chemical reactivity [22]. In order to confirm the results obtained, the TBARs method was used to assess the rate of oxidation of 2-deoxy-d-ribose mediated by Cu(II) sulphate and Cu(II) complexes with imines. or Gly-derived Y-27632 ...
Most pollutants in the Earths atmosphere are removed by oxidation with highly reactive hydroxyl radicals. Field measurements have revealed much higher concentrations of hydroxyl radicals than expected in regions with high loads of the biogenic volatile organic compound isoprene1, 2, 3, 4, 5,6, 7, 8. Different isoprene degradation mechanisms have been proposed to explain the high levels of hydroxyl radicals observed5, 9, 10, 11. Whether one or more of these mechanisms actually operates in the natural environment, and the potential impact on climate and air quality, has remained uncertain12, 13, 14. Here, we present a complete set of measurements of hydroxyl and peroxy radicals collected during isoprene-oxidation experiments carried out in an atmospheric simulation chamber, under controlled atmospheric conditions. We detected significantly higher concentrations of hydroxyl radicals than expected based on model calculations, providing direct evidence for a strong hydroxyl radical enhancement due ...
1, 10 copper phenanthroline assay is a frequently used assay to examine the pro-oxidative activity of extracts against DNA [26]. On addition of reagents and subsequent incubation, a complex called bis (1, 10 - phenanthroline copper) is formed which links to DNA and breaks down its strand; hydroxyl radical generation is primarily implicated in DNA damage [39]. However, if the cuprous ions are bound, DNA degradation does not occur. When reducing agent ascorbic acid (which is a proven pro-oxidant at higher concentration [40]) is added to the complex, Cu(II) in the complex gets converted to Cu(I) and hence, there is additional production of hydroxyl radicals that breaks down DNA into TBARS (Thiobarbituric Acid Reactive Substance). Hence, the level of TBARS formed in different extracts/fractions can indirectly reveal the quantity of hydroxyl radicals generated and give an estimation of the pro-oxidant or anti-oxidant activity of the extract/fractions at varying concentration. ROS (Reactive Oxygen ...
Rate constants for the gas‐phase reactions of hydroxyl radicals and chlorine atoms with aliphatic alcohols and ethers have been determined at 298 ± 2 K and at a total pressure of 1 atmosphere. The OH radical rate data were obtained using both the absolute technique of pulse radiolysis combined with kinetic UV spectroscopy and a conventional photolytic relative rate method. The Cl atom rate constants were measured using only the relative rate method. Values of the rate constants in units of 10−12 cm3 molecule−1 s−1 are: (Formula Presented.) The above relative rate constants are based on the values of 퓀(OH + c‐C6H12) = 7.49 × 10−12 cm3 molecule−1 s−1 and 퓀(Cl + c‐C6H12) = 311 × 10−12 cm3 molecule−1 s−1. Attempts to corre late the trends in the rate constant data in terms of the bond dissociation energies and inductive effects are discussed. ...
Two lines of evidence connect metals to Alzheimer s disease. First, metals promote the aggregation of Aß peptide in vitro (Atwood et al., 1998), probably via metal-catalyzed oxidation of the Aß peptide (Dyrks et al., 1992), and second, metals such as copper and iron are accumulated in plaques (Lovell et al., 1998). Interestingly, Aß peptide in a soluble state generates hydrogen peroxide with concomitant TBARS signals, probably by the generation of hydroxyl radical formation (Huang et al., 1999) via Fenton-like or Haber-Weiss reactions (Haber and Weiss, 1934; Halliwell and Gutteridge, 1990). The mechanisms involved in the Aß-mediated neurotoxicity are unknown, although the fibril state of Aß is apparently necessary for the toxicity observed in neuronal cultures (Iversen et al., 1995; Bonnefont et al., 1998; Muñoz and Inestrosa, 1999; Calderón et al., 1999). We hypothetized that the interaction of amyloid fibrils and metals with oxidative properties such as copper may be a source of ...
CaoWei; ChenWeiJun; SuoZhiRong; YaoYaPing, 2008: Protective effects of ethanolic extracts of buckwheat groats on DNA damage caused by hydroxyl radicals
TY - JOUR. T1 - ESTIMATES OF ATMOSPHERIC HYDROXYL RADICAL CONCENTRATIONS FROM THE OBSERVED DECAY OF MANY REACTIVE HYDROCARBONS IN WELL-DEFINED URBAN PLUMES. AU - BLAKE, N J AU - PENKETT, S A AU - CLEMITSHAW, K C AU - ANWYL, P AU - LIGHTMAN, P AU - MARSH, A R W AU - BUTCHER, G PY - 1993. Y1 - 1993. M3 - Article. VL - 98. SP - 2851. EP - 2864. JO - Journal of Geophysical Research - Atmospheres. JF - Journal of Geophysical Research - Atmospheres. SN - 2169-897X. IS - D2. ER - ...
https://www.sciencedirect.com/science/article/pii/S1385894719315578?dgcid=coauthor#bb0080 Title : Origin of Hydroxyl Radicals in a Weakly Ionized Plasma-Facing Liquid Authors : Sanghoo Park, Joo Young Park, Wonho Choe Journal : Chemical Engineering Journal
A microbicidal filter system having superior drop pressure and low complexity is provided, as well as a method for producing the same. The system comprises a plurality of glass beads having pores formed therebetween for the flow of air therethrough. The sintered glass beads are coated in a transition metal oxide and water. An ultraviolet light source is used to cause a photocatalytic reaction between the transition metal oxide and water. Free hydroxyl radicals with microbicidal properties are produced. Urethane foam may be inserted between the glass beads before sintering in order to cause a bimodal pore size distribution, and particulates disposed on the glass beads may be added to alter surface activity.
Introduction. The oxidative status of cells is determined by the balance between pro-oxidants and antioxidants. Oxidants are compounds that can accept electrons, as opposed to reductants that donate electrons. Pro-oxidants are referred to as reactive oxygen species (ROS). The toxicity of ROS depends on their reactivity and life span. Longer life span permits them to diffuse, interact with sensitive biological substrates and cause damage to various organelles. Most of the transition metals, such as iron, can convert relatively stable oxidants into powerful radicals. Excess iron catalyzes hydroxyl radical generation from activated oxygen species by the Haber-Weiss and Fenton reactions.1. The intracellular response to oxidative-stress in erythropoiesis involves the transcription factor, Forkhead box O3a (FoxO3a), which controls pathway(s) regulating erythroid maturation and the levels of oxidative stress in murine erythropoiesis.2 Activation of FoxO3a has been proposed as a protective mechanism in ...
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The proton transfer reaction is a process of great significance to a wide range of fields, including nuclear engineering, space travel and environmental remediation. The observation was made possible by the availability of ultrafast X-ray free-electron-laser pulses, and is basically unobservable by other ultrafast methods. While studying the fastest chemical reactions is interesting in its own right, this observation for water also has important practical implications.. The truly exciting thing is that weve witnessed the fastest chemical reaction in ionized water, which leads to the birth of the hydroxyl radical, said Argonne distinguished fellow Linda Young, the senior corresponding author of the study. ​The hydroxyl radical is itself of considerable importance, as it can diffuse through an organism, including our bodies, and damage virtually any macromolecule including DNA, RNA, and proteins.. By understanding the time scale for the formation of the chemically aggressive hydroxyl ...
4-aminophenol is soluble (6500 mg/L) and is inherently biodegradable in water with pre-adapted sludge. It has a low capacity to volatilise from solution to the air (Henrys law constant of 8.954E-005 Pa m3/mol-1) and undergoes rapid phototransformation in the atmosphere (half-life of 1.7 hours in the presence of hydroxyl radicals at1.5X10+6 hydroxyl radicals per cu assuming 12 hours daylight). The partitioning coefficient (log Kow = -0.09) indicates that 4-aminophenol does not have a high potential for adsorption to soil or sediment (log Koc = 0.59). It has a low potential for bioaccumulation in aquatic and terrestrial habitats (BCF ,=0.46 L/kg). Assuming predominate emissions to the water compartment, Mackay Level III fugacity predictions estimate 1.61%, 98.2%, 0.18% and 3.24e-007 % partitioning in the soil, water, sediment and air compartments, respectively. 4 -aminophenol is amphoteric with both amine and hydroxyl functional groups; pKa values for these groups are 5.48 and 10.46, ...
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Because the substance is determined as readily biodegradable, photodegradation is not important to investigate for environmental fate of the substance. However, an estimation of the indirect photodegradability of menthols in the atmosphere by hydroxyl radicals was conducted for the substance. Under the premise of the pseudo-first order reaction with hydroxyl radicals in air, the rate constant of 2.4 E -11 cm3/molecule/s and corresponding half-life 16 hours were calculated. ...
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Packaging. PP bags with a plastic liner net weight 25 kg.. Transportation and storage. The product is transported by all modes of transport in accordance with the rules of goods carriage, valid for this mode of transport. Sodium formate technical is transported in closed transport facilities. The product is stored in covered accomodation, on pallets at the height of no less than 5 cm from the floor and at a distance of no less than 1 m from the heating units.. Manufacturers guaranty. Guaranty period of storage to be 1 year from the manufacturing date, provided that all transportation and shipment rules are observed. Please download information on the product in PDF format. ...
Sodium Formate is a white crystalline material. It is used in the production of sodium hydrosulphite, a bleaching agent for pulp and paper, in the leather tanning process. Features. ...
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Article Heterogeneous Fenton-like degradation of an azo dye reactive brilliant orange by the combination of activated carbon–FeOOH catalyst and H|sub|2|/sub|O|sub|2|/sub|. The decoloration of an azo dye reactive brilliant orange (X-GN) by a he...
Microaccidents are damages that are caused by free radicals, mutagens and many harmful chemicals. Free radicals are chemicals with an unpaired electron, which are extremely and randomly reactive with whatever cellular structures present, inflicting damage as a result. A free radical is an unstable molecule that steals an electron from a stable molecule in order to satisfy its need for repair. When this free radical destabilizes the stable molecule it creates another free radical in a vicious chain reaction of cellular destruction. A single free radical can cause damage to millions of other molecules in you body, preventing your body from functioning properly. This molecular destruction is continually occurring in your body. Free radicals attack us from many different environmental sources every day. There are many researches demonstrating that free radical damage accumulates with age. People often ask: if free radical damage is one of the key mechanisms of aging then taking antioxidant ...
The new edition of this well-established book is thoroughly revised and gives a comprehensive account of the role of free radicals, other reactive species (RS), and antioxidants in life, health, and ... More. The new edition of this well-established book is thoroughly revised and gives a comprehensive account of the role of free radicals, other reactive species (RS), and antioxidants in life, health, and disease. Chapter 1 reviews how oxygen (O2) is used by living organisms, why it can be toxic, and introduces the concept of oxygen radicals and other RS; their chemistry is detailed in Chapter 2, especially for superoxide, hydroxyl radical (including Fenton chemistry), peroxynitrite, nitric oxide, ozone, and singlet O2, with emphasis on their redox properties. Subsequent chapters detail what antioxidants can be made in vivo (e.g. superoxide dismutases, peroxiredoxins) and which can come from diet (e.g. vitamins E and C, carotenoids, and polyphenols such as the flavonoids) and how they work in ...
What Does This Mean?. Changes in metabolites may be a response to altered biochemical pathways due to disease (Jones 2010). We believe that a change in our patients acylcarnitine profiles is a useful indicator of changes in their metabolic states. Monitoring these changes in our patients could be an opportunity to advance understanding of the mechanism of their diseases, finding new biomarkers, or new therapies.. The formation of acylcarnitines is important not only in the metabolism of fatty acids but is also an important pathway in the mechanism of the ketogenesis. Carnitine could also be involved in a host of other pathways by consequence of its free hydroxyl group. It has been suggested that L-carnitine can complex with various other metabolites and carboxylic acids of varying lengths to transport them throughout the body for a variety of functions (Jones 2010).. Our Focus. In some research circles it is believed that changes in the concentration of carnitine can be used to identify changes ...
Uncontrolled free radicals damage body cells either by breaking down the cell membrane, by attacking the internal working of the cell, or by going right to the nucleus to attack the genetic material. A fundamental way that free radicals cause their damage is by breaking down natural body fats. Since the cell membrane is composed of fatty tissue (called lipids), it is a target for free radical attack. They may destroy the cell membrane, so that it cannot take in nutrients or release wastes. This leads eventually to the collapse and death of the cell. Free radicals can damage white blood cells and particularly the defender T cells, both of which are key to a strong immune system--and enable you to ward off bacteria and viruses. Free radicals may also weaken essential antibodies that are produced by the immune system to protect from disease, resulting in susceptibility to communicable diseases. Uncontrolled free radicals may disturb nerve chemicals, which can affect the brain and nervous system. ...
C Berry, MJ Brosnan, MY Alexander, CA Hamilton, JJV McMurray, AF Dominiczak; Mechanisms of Oxidative Free Radical Generation in Human Arteries. Clin Sci (Lond) 1 August 2001; 101 (s45): 7P. doi: https://doi.org/10.1042/cs101007P. Download citation file:. ...
Research title: Concurrent electro-generation of hydroxyl radicals and its precursor H2O2 and their utilization in persistent pollutant treatment. ...
Research title: Concurrent electro-generation of hydroxyl radicals and its precursor H2O2 and their utilization in persistent pollutant treatment. ...
The hydroxyl group is a functional group characterized by the presence of an oxygen atom covalently bonded to a hydrogen atom (R-OH). It is also called alcohol group, and the molecules that contain it have in their names the suffix ol. In biochemistry, this group is particularly important because it can act both as donor and acceptor of H in hydrogen bonds. Therefore, their presence in biomolecules increases their water solubility and hydrophilic character. ...
The Human Half-Cell Effect When your cells are under stress from exertion (say after a hard workout) these escaped free radicals attack your cells. Free radical
Interleukin-10 (IL-10) is a pleiotropic cytokine that controls inflammatory processes by suppressing the production of proinflammatory cytokines that are known to be transcriptionally regulated by nuclear factor-B (NF-B). Although still controversial, IL-10 has been shown to inhibit NF-B activation through a process that involves proteolytic degradation of inhibitory subunit IB-. What is not known
Alpha and Beta hydroxyl acids also known as AHAs and BHAs respectively, are very popular in anti-aging skin care products. These products actually do
Sestavine: AQUA LAURETH-7 SODIUM COCOATE ALCOHOL Disodium hydrogen citrate SODIUM LAURETH SULFATE Olive oil sodium salt SODIUM FORMATE Amide polyglycol ether…
As stated I am not a chemist, but I need help on a question I have. Assume I have a Formic acid 75% and I add between 5-10 kg to 1.000 liter of water. If I wanted to add sodium formate and HCl 37% to ...
Much maligned and misunderstood, ME gets a radical makeover by a psychologist. But is this pathway really so radical? Perhaps only if you are a health
CIMmultus™ stands for: Convective mass transfer, reduced backpressure, and minimal sample clogging Fast product isolation and concentration of
Molecular Cloning, also known as Maniatis, has served as the foundation of technical expertise in labs worldwide for 30 years. No other manual has been so popular, or so influential.
Kolagén je produkovaný predovšetkým väzivovými bunkami (fibroblasty), bunkami chrupavky (chondroblasty), kostnými bunkami (osteoblasty), ale i epitelovými bunkami. Syntéza z časti prebieha vnútri bunky, čiastočne extracelulárne. Polypeptidové reťazce sú syntetizované na hrubom endoplazmatickom retikule. Vzniknutý prokolagén je vylúčený do extracelulárneho priestoru, kde z neho enzým prokolagénpeptidáza odštiepi tropokolagén. Ten reaguje s ostatnými molekulami tropokolagénu a za prítomnosti katalyzátora, ktorým je enzým lyzyloxidáza, vytvára mikrofibrily. Následne po syntéze prechádzajú molekuly kolagénu posttranslačnou modifikáciou, ktorá bielkovine zaistí plnú funkčnosť. Medzi tieto modifikácie patrí aj hydroxylácia, kedy sa hydroxylová skupina viaže v pomere 1:1000 aminokyselinových molekúl. Preto je hydroxylácia pre správnu funkciu kolagénu nenahraditeľná [13].. V štúdii, ktorá skúma kolagénovú ultraštruktúru transmisným ...
In the wake of Nikes stand for racial equality, businesses worldwide are waking up to the potential of social action on both people and profit. As new generations demand purpose from the organizations they engage with, radical action is increasingly becoming the norm.
Its not enough for managers to talk about customer orientation and focus. They have to measure the internal processes that will--or will not--make it happen.
IF YOURE keen to catch sight of what the Conservative party might look like in a decades time, you should make your way to the Sonata room at the
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... hydroxyl radicals (HO•) and alkyl radicals (R•). Oxidation begins with the formation of alkyl radicals, which are formed when ... act as radical scavengers and remove peroxy radicals (ROO•), as well as to a lesser extent alkoxy radicals (RO•), ... The aminoxyl radical (N-O•) combines with free radicals in polymers: N-O• + R• → N-O-R Although they are traditionally ... These alkyl radicals react very rapidly with molecular oxygen (rate constants ≈ 107-109 mol-1 s-1) to give peroxy radicals, ...
In addition, hydroxyl radicals (•OH) are formed which interact with the fatty acids of membranes, causing disruption of ... but when there is too much Proto it interacts with light to form singlet oxygen radicals (1O2). These interact with the fatty ...
The corresponding electrically neutral compound HO• is the hydroxyl radical. The corresponding covalently bound group -OH of ... and this makes detection of hydroxyl groups by infrared spectroscopy relatively easy. A band due to an OH group tends to be ...
It reacts with hydroxyl radical (•OH) to produce a radical intermediate •HOCO, which transfers rapidly its radical hydrogen to ... and hydroxyl radical. NO2 gives O(3P) via photolysis, thereby forming O3 following reaction with O2. Since hydroxyl radical is ... CO can react chemically with other atmospheric constituents (primarily the hydroxyl radical, OH.) that would otherwise destroy ... O2 to form peroxy radical (HO2•) and carbon dioxide (CO2). Peroxy radical subsequently reacts with nitrogen oxide (NO) to form ...
Cadet J, Delatour T, Douki T, Gasparutto D, Pouget JP, Ravanat JL, Sauvaigo S (March 1999). "Hydroxyl radicals and DNA base ... and another end at which there is a free hydroxyl group attached to the 3′ carbon of a ribose (the 3′ hydroxyl). The ... These enzymes function by repeatedly adding a nucleotide to the 3′ hydroxyl group at the end of the growing polynucleotide ... On the other hand, oxidants such as free radicals or hydrogen peroxide produce multiple forms of damage, including base ...
I. Detection of the Hydroxyl Radical". The Journal of Chemical Physics. 46 (3): 967-972. doi:10.1063/1.1840834. "Apparatus for ...
Reactive oxygen species, ROS, such as superoxide (O2- • ), hydrogen peroxide (H2O2), hydroxyl radicals (HO•), and singlet ... DSBs are mainly caused by free radicals generated from ionizing radiation in the environment and from by-products released ...
Chen SX, Schopfer P (March 1999). "Hydroxyl-radical production in physiological reactions. A novel function of peroxidase". Eur ...
Oxygen-based radicals, especially hydroxyl radicals, HO•, can oxidize hydroxyl groups in the cellulose chains to ketones, and ... facilitate many radical reactions and impact oxygen delignification. While the radical reactions are largely responsible for ... Oxygen exists as a ground state triplet state, which is relatively unreactive and needs free radicals or very electron-rich ... The chemistry is very similar to that involved in oxygen delignification, in terms of the radical species involved and the ...
The hydroxyl radical •OH combines with H2S to form HS• and water. Other reactions investigated by Tiee (1981) are HS• + ... Sulfanyl (HS•), also known as the mercapto radical, hydrosulfide radical, or hydridosulfur, is a simple radical molecule ... HS• is formed in the Earth's atmosphere by the reaction of HO•, the hydroxyl radical, on carbon disulfide, carbon oxysulfide ... radical then passing a proton to water to make the HS• radical. M is a metal such as zinc or copper. This has potential for ...
... in which hydroxyl radical is generated from hydrogen peroxide. The hydroxyl radical then can modify amino acids. For example, ... hydroxyl radical) and H2O2 (hydrogen peroxide). Further, some reactive oxidative species act as cellular messengers in redox ... However, AstraZeneca's radical scavenging nitrone drug NXY-059 shows some efficacy in the treatment of stroke. Oxidative stress ... For example, in tissues and cells, the free radical oxidation of linoleic acid produces racemic mixtures of 13-hydroxy-9Z,11E- ...
As potent antioxidants, they specifically trap hydroxyl radicals. It is therefore believed that this is in different biological ... Okada, Y; Kaneko, M; Okajima, H (1996). "Hydroxyl radical scavenging activity of naturally occurring furan fatty acids". Biol ... Furan fatty acids are very effectively acting as radical scavengers. In this process dioxoenoic fatty acids are formed, which ... Spiteller, G (2008). "Peroxyl radicals are essential reagents in the oxidation steps of the Maillard reaction leading to ...
Then, hydroxyl radical transfers its radical to DNA. Or together with hydronium and electron, a free hydroxyl radical can ... Indirect radiation occurs from radiolysis of water, creating a free hydroxyl radical, hydronium and electron. ... Direct radiation creates a free DNA radical from radiation energy deposition that damages DNA. ...
... which can go on to produce the highly reactive hydroxyl radical (OH•), initiating a cascade of cytotoxic free radicals; this ... generating a photosensitiser radical anion (Psen•−) and a substrate radical cation (Subs•+). The majority of the radicals ... These species include singlet oxygen (1O2), hydroxyl radicals (•OH) and superoxide (O2−) ions. They can interact with cellular ... These are free radicals (Type I) generated through electron abstraction or transfer from a substrate molecule and highly ...
... is degraded by attack of hydroxyl radicals. When exposed to sunlight in aqueous solutions, isophorone undergoes 2+2 ...
One scheme is MCPA oxidation by hydroxyl radical, •OH. The hydroxyl radical adds on the ring, followed by radical transfer to ... With oxygen present, the addition of the hydroxyl radical leads the cleavage of the ether link, yielding MCP. The other scheme ...
Free radicals such as superoxide, hydroxyl, and hydroperoxyl. The composition of the human body can be viewed on an atomic and ... Ethane and pentane are produced by oxygen free radicals. Many other small molecules, such as amino acids, fatty acids, ...
Typically, atmospheric CH4 is oxidized by hydroxyl radicals (•OH), but H2 can also react with •OH to reduce it to H2O. C H 4 + ... Another major sink of free atmospheric H2 is photochemical oxidation by hydroxyl radicals (•OH), which forms water. ...
... with the O-O bond cleaving to form two hydroxyl radicals. H2O2 → 2 ·OH Certain azo compounds (such as azobisisobutyronitrile), ... Since molecular oxygen can abstract H atoms from certain radicals, the HOO· radical is easily created. This particular radical ... peroxides can further cleave photolytically into two hydroxyl radicals. More commonly, HOO can react with free oxygen atoms to ... can also photolytically cleave, forming two alkyl radicals and nitrogen gas: RCH2-N=N-H2CR → 2 RCH2 + N2 These free radicals ...
For the typical TOC levels in UPW systems most methods utilize hydroxyl radicals in the liquid phase. There are multiple ... Typical equations showing persulfate generation of hydroxyl radicals follows. S2O8-2 + hν (254 nm) → 2 SO2-1• and SO2-1 • + H2O ... The 184 nm UV light is energetic enough to break the water molecule into OH and H radicals. The hydrogen radicals quickly react ... the hydroxyl radical (OH•). Organic oxidation in a combustion environment involves the creation of other energized molecular ...
The Haber-Weiss reaction generates •OH (hydroxyl radicals) from H2O2 (hydrogen peroxide) and superoxide (•O2−) catalyzed by ... The hydroperoxyl radical is a weak acid and gives rise to the superoxide radical (O2•-) when it loses a proton: HO2 → H+ + O2- ... Below a pH of 4.7, the protonated hydroperoxyl radical will dominate in solution while at pH above 4.7 the superoxide radical ... the chain is terminated when the hydroxyl radical is scavenged by a ferrous ion: Fe2+ + HO• + H+ → Fe3+ + H2O (step 4: ...
... superoxide radical anions, and other radicals. Nitrate and nitrite ions produce hydroxyl radicals under irradiation. Indirect ... These constants are known for hydroxyl radical and molecular oxygen. In the absence of such rate constants, quantitative ... E.g., N,N-dimethylaniline, used as a probe for the carbonate radical reacts very quickly with DOM-excited triplet states and ...
... with free radicals such as the hydroxyl radical (HO·) and hydroperoxyl (HOO·) being formed. Non-metallic catalysts include ... It is then quickly dissociated to OH· radicals. The radicals serve as initiator of radical polymerization, which surrounds the ... based on how readily hydrogen peroxide can decompose into a hydroxyl radical and how superoxide radical byproducts of cellular ... H 2O 2 is a source of hydroxyl radicals (·OH), which are highly reactive. H 2O 2 is used in the Briggs-Rauscher and Bray- ...
Hydroperoxides readily undergo photolysis to give an alkoxyl macroradical radical (PO•) and a hydroxyl radical (HO•), both of ... Hyroperoxide undergoes photolysis to form hydroxyl and alkoxyl radicals. These initiation steps generate macroradicals at ... Radicals formed at hydrocarbon sites rapidly convert to alkenes with loss of radical chlorine. This forms allylic hydrogens ( ... non-radical\ product}}} P ∙ + P ∙ ⟶ cross linking reaction to non − radical product {\displaystyle {\ce {P\bullet +\ P\bullet ...
... hydroxyl radical) ONOO− + CO2 (carbon dioxide) → ONOOCO2− (nitrosoperoxycarbonate) ONOOCO2− → •NO2 (nitrogen dioxide) + O=C(O•) ... Dröge W (January 2002). "Free radicals in the physiological control of cell function". Physiological Reviews. 82 (1): 47-95. ... O− (carbonate radical) •NO + •NO2 ⇌ N2O3 (dinitrogen trioxide) Peroxynitrite can react directly with proteins that contain ... Free Radical Biology and Medicine. 25 (4-5): 392-403. doi:10.1016/S0891-5849(98)00095-1. PMID 9741578. ...
Radical scavengers proved a viable method of measuring production of hydroxyl radical. Meso-diphenylhelianthrene can be used ... into nitrate photolysis have used 2-nitrobenzaldehyde and benzoic acid as a radical scavenger for hydroxyl radicals produced in ... "Quantum Yields of Hydroxyl Radical and Nitrogen Dioxide from the Photolysis of Nitrate on Ice". The Journal of Physical ... In situ photoformation of hydroxyl radical and singlet molecular oxygen". Atmospheric Environment. 35 (6): 1079-1089. Bibcode: ...
Abuin, E.; Encina, M. V.; Diaz, S.; Lissi, E. A. (July 1978). "On the reactivity of diethyl hydroxyl amine toward free radicals ... Antiozonant Radical scavenger "N,N-diethylhydroxylamine - Compound Summary". PubChem Compound. USA: National Center for ...
The last reaction of atomic nitrogen with the hydroxyl radical, •HO, was added by Lavoie, Heywood and Keck to the mechanism and ... During daytime, NO2 reacts with hydroxyl radicals (·OH) and forms nitric acid (HNO3), which can easily be removed by dry and ... Then, photolysis of NO2 leads to the formation of ozone and the further formation of hydroxyl radicals (·OH) through ozone ... First of all, through the reaction of NO with HO2 radicals, •OH radicals are recycled, which oxidize methane molecules, meaning ...
"Oxidative degradation of fensulfothion by hydroxyl radical in aqueous medium". Chemosphere. 91 (3): 295-301. Bibcode:2013Chmsp ...
The first is due to the reaction of hydroxyl radicals (•OH) with ozone. •OH is formed by the reaction of electronically excited ... Radicals produced from the homolytically split oxygen molecules combine with molecular oxygen to form ozone. Ozone in turn is ... The HO2 radical produced by the reaction of OH with O3 is recycled to OH by reaction with oxygen atoms or ozone. In addition, ... the so-called NOx radical cycles also deplete stratospheric ozone. Finally, chlorofluorocarbon molecules are photolysed in the ...
Hydroxyl radical. *இரும்பு(II) ஆக்சைடு. *Magnesium monohydride cation. *Methylidyne radical. *நைட்ரிக் ஆக்சைடு ...
The meta-hydroxyl group of catechol is methylated by catechol-O-methyltransferase. Four of the five hydroxyl groups of ... Williams RJ, Spencer JP, Rice-Evans C (Apr 2004). "Flavonoids: antioxidants or signalling molecules?". (review). Free Radical ... The exception is the 5-hydroxyl group of the flavonoid ring which generally does not undergo glucuronidation. The major ... Quercetin contains a polyphenolic chemical substructure that stops oxidation by acting as a scavenger of free radicals that are ...
This reaction must be carried out in the dark, since the formation of bromine radicals is stimulated by light. This would lead ... Hydroxyl value. *Hydrogen number. ReferencesEdit. *^ a b Thomas, Alfred (2002). "Fats and Fatty Oils". Ullmann's Encyclopedia ...
Hydroxyl radical. *Iron(II) oxide. *Magnesium monohydride cation. *Methylidyne radical. *Nitric oxide ...
The aromatic ring in 6 is activated at positions ortho to the hydroxyl group, and is alkylated by 5, an alkylating agent. The ... and cleavage is postulated to be initiated by a radical reaction.[19] ...
Hydroxyl radical. *Iron(II) oxide. *Magnesium monohydride cation. *Methylidyne radical. *Nitric oxide ...
Hydroxyl radical. *Iron(II) oxide. *Magnesium monohydride cation. *Methylidyne radical. *Nitric oxide ... hydroxyl can chemically attack the adjacent phosphodiester bond to cleave the phosphodiester backbone. The hydroxyl group also ... The major difference between RNA and DNA is the presence of a hydroxyl group at the 2'-position of the ribose sugar in RNA ( ... However, RNA is less stable, being more prone to hydrolysis due to the presence of a hydroxyl group at the ribose 2' position. ...
Indirect ionization happens as a result of the ionization of water, forming free radicals, notably hydroxyl radicals, which ... Some types of cancer are notably radioresistant, that is, much higher doses are required to produce a radical cure than may be ... Another method is to shrink the tumor with neoadjuvant chemotherapy prior to radical radiation therapy. A third technique is to ... In photon therapy, most of the radiation effect is through free radicals. Cells have mechanisms for repairing single-strand DNA ...
Hydroxyl radical. *Iron(II) oxide. *Magnesium monohydride cation. *Methylidyne radical. *Nitric oxide ...
Hydroxyl radical. *இரும்பு(II) ஆக்சைடு. *Magnesium monohydride cation. *Methylidyne radical. *நைட்ரிக் ஆக்சைடு ...
c) any combination of up to 5 alkyl radicals and/or alkoxy radicals (each with up to 6 carbon atoms, including cyclic radicals ... substitution in or on the piperidine ring with alkyl, alkenyl, alkoxyl, ester, ether, hydroxyl, halo, haloalkyl, amino or nitro ... a) an acetyl, propionyl, butenoyl or butanoyl radical, attached to the aniline nitrogen atom: (b) 1 or more alkyl radicals, ... "Fentanyl analogues, in which the N-[1-(2-phenethyl)-4-piperidyl]aniline nucleus has additional radicals, either alone or in ...
... radical (chemistry) radioisotope Radium Radon Radon fluoride Raman spectroscopy Raoult's law Redox Reduction Reflux Reversible ... Hydrochloric acid hydrogen Hydrogen bond Hydrogen cyanide Hydrogen peroxide Hydrogen sulfide Hydrolysis hydroxide hydroxyl ...
... deamination of dopamine and the subsequent reaction of accessible ferrous iron to generate highly toxic hydroxyl radicals".[12] ...
KenichiK. Iwasaki KenichiK. i inni, Anticancer effect of linalool via cancer-specific hydroxyl radical generation in human ...
Hydroxyl radical. *Iron(II) oxide. *Magnesium monohydride cation. *Methylidyne radical. *Nitric oxide ...
Phenolics combine an aromatic carbon ring with a hydroxyl group. There are a number of different phenolics such as lignins, ... which produce free radicals disrupting DNA, protein, and lipids, and can cause skin irritation. ...
It has two hydroxyl groups bonded to a benzene ring in a para position. It is a white granular solid. Substituted derivatives ... and other monomers that are susceptible to radical-initiated polymerization. This application exploits the antioxidant ... Hydroquinone can lose a proton from both hydroxyl groups to form a diphenolate ion. The disodium diphenolate salt of ...
... and free radicals such as the hydroxyl radical (·OH) and the superoxide anion (O2−).[56] The hydroxyl radical is particularly ... The free radicals then react with oxygen to produce peroxy radicals which cause yet further damage, often in a chain reaction. ... Hail N, Cortes M, Drake EN, Spallholz JE (July 2008). "Cancer chemoprevention: a radical perspective". Free Radical Biology & ... "Free Radical Biology & Medicine. 43 (1): 4-15. doi:10.1016/j.freeradbiomed.2007.03.024. PMC 2040110 . PMID 17561088.. ...
In addition, aspirin induces the formation of NO-radicals in the body, which have been shown in mice to have an independent ... causing a chemical reaction that turns salicylic acid's hydroxyl group into an ester group (R-OH → R-OCOCH3). This process ...
Hydroxyl radical. *Iron(II) oxide. *Magnesium monohydride cation. *Methylidyne radical. *Nitric oxide ...
Free radical reactions[edit]. Reactions of C60 with free radicals readily occur. When C60 is mixed with a disulfide RSSR, the ... Hydroxyl radical. *Iron(II) oxide. *Magnesium monohydride cation. *Methylidyne radical. *Nitric oxide ... Stability of the radical species C60Y• depends largely on steric factors of Y. When tert-butyl halide is photolyzed and allowed ... radical C60SR• forms spontaneously upon irradiation of the mixture.. ...
Mannitol is a powerful scavenger for hydroxyl radicals, which are generated during the peroxidation of lipids in biological ... which are connected by an ester bond to the hydroxyl groups of quinic acid.[34] The antioxidant capacity of chlorogenic acid is ... more potent than of ascorbic acid (vitamin C) or mannitol, which is a selective hydroxy-radical scavenger.[35] Chlorogenic ...
Poeggeler B, Reiter RJ, Tan DX, Chen LD, Manchester LC (May 1993). "Melatonin, hydroxyl radical-mediated oxidative damage, and ... especially the hydroxyl radical that attacks DNA, proteins, and cellular membranes. Melatonin has been described as a broadly ... multiplicity of mechanisms from radical detoxification to radical avoidance". Endocrine. 27 (2): 119-30. doi:10.1385/ENDO:27:2: ... 1. A slow transfer of one electron from the THB to O2 could produce a superoxide which could recombine with the THB radical to ...
MO diagram for π orbitals on the allyl radical. The middle MO labeled Ψ2 is singly occupied in the allyl radical. In the allyl ... Thus, CH2=CHCH2OH "has an allylic hydroxyl group". Allylic C−H bonds are about 15% weaker than the C−H bonds in ordinary sp3 ... The allyl group is widely encountered in organic chemistry.[1] Allylic radicals, anions, and cations are often discussed as ... The weakened C−H bonds reflect the high stability of the resulting pentadienyl radicals. Compounds containing the C=C−CH2−C=C ...
... such as hydroxyl and oxygen radicals, which in turn can damage DNA. The DNA damage caused indirectly to skin by UVA consists ... "Free Radical Biology and Medicine. 41 (8): 1205-1212. doi:10.1016/j.freeradbiomed.2006.06.011. PMID 17015167.. ... Damiani, E.; Greci, L.; Parsons, R.; Knowland (1999). "Nitroxide radicals protect DNA from damage when illuminated in vitro in ... free radicals such as reactive oxygen species). UVA can generate highly reactive chemical intermediates, ...
... as NO is a free radical with an unpaired electron. It is the proximate cause of septic shock and may function in autoimmune ... Oxidation of L-Arg to L-citrulline occurs via two successive monooxygenation reactions producing Nω-hydroxy-L-arginine (NOHLA) ...
Hydroxyl radical. *இரும்பு(II) ஆக்சைடு. *Magnesium monohydride cation. *Methylidyne radical. *நைட்ரிக் ஆக்சைடு ... free radicals) உற்பத்தி செய்யப்படுகின்றன. மாசற்ற சுற்றுச் சூழலுக்கு அதிகம் இலக்காகும் போதும், புற ஊதக் கதிர்களின் தாக்குதலுக்கு ...
Free radical and singlet oxygen oxidations[edit]. Oxidative stress in cells and tissues produces Free radical and singlet ... Like most polyunsaturated fatty acids and mono-hydroxyl polyunsaturated fatty acids, 13(S)-HODE is rapidly and quantitatively ... Frankel, E.N (1984). "Chemistry of free radical and singlet oxidation of lipids". Progress in Lipid Research. 23 (4): 197-221. ... Free radical and singlet oxygen oxidations of linoleic acid produce a similar set of 13-HODE metabolites (see 9- ...
In terms of structure, cryptoxanthin is closely related to β-carotene, with only the addition of a hydroxyl group. It is a ... As with other carotenoids, cryptoxanthin is an antioxidant and may help prevent free radical damage to cells and DNA, as well ...
"Trends in the Hydroxyl Free Radical" (PDF) (IPCC AR4 WG1). IPCC. The hydroxyl free radical (OH) is the major oxidizing chemical ... The hydroxyl radical, •OH, is the neutral form of the hydroxide ion (OH−). Hydroxyl radicals are highly reactive (easily ... Hydroxyl radicals instantly denature Der p1 and Der f1 (house dust mites). Hydroxyl radicals oxidise their protein structures, ... However, humans, animals and plants have evolved to coexist with hydroxyl radicals, and hydroxyl radicals cannot enter the ...
Hinkley, R.K.; Walker, T.E.H.; Richards, W.G., On the e.p.r. spectrum of vibrationally excited hydroxyl radicals, Proc. R. Soc ... Clough, P.N.; Curran, A.H.; Thrush, B.A., The e.p.r. spectrum of vibrationally excited hydroxyl radicals, Proc. R. Soc. London ... Destombes, J.-L.; Marliere, C.; Rohart, F.; Burie, J., Nouvelle analyse du spectre hertzien du radical hydroxyl, C.R. Acad. Sci ... Meerts, W.L., On the microwave spectrum of the X2«PI» state of the hydroxyl radical, Chem. Phys. Lett., 1977, 46, 24. [all data ...
Hydroxyl radicals generated by hydrogen peroxide photolysis recondition biofilm-contaminated titanium surfaces for subsequent ...
However, the inhibitory effects of CGA on specific radical species are not well understood. Electron spin resonance (ESR) in ... combination with spin trapping techniques was utilized to detect free radicals. 5,5-Dimethyl-1-pyrroline-N-oxide (DMPO) was ... was used as a spin trapping reagent while the Fenton reaction was used as a source of hydroxyl radical (*OH). We found that CGA ... However, the inhibitory effects of CGA on specific radical species are not well understood. Electron spin resonance (ESR) in ...
... which neutralizes hydroxyl radicals by means of the aromatic hydroxylation reaction. Similar action against hydroxyl radicals ... In living organisms there are two major reactive oxygen species, superoxide radical and hydroxyl radical that are being ... by virtue of their addition to double bonds with the formation of a corresponding hydroxyl derivative:. Thus, a general ... was recently documented to be an effective hydroxyl radical scavenger by virtue of the addition of hydroxyl groups to the ...
Electron spin resonance (ESR) was used to investigate the reoction of taurine and hypotaurine with hydroxyl radicals (OH). The ... Free-radicals; Free-radical-generation; Cell-function; Cell-damage; Cell-biology; Cellular-reactions; Lipid-peroxidation; ... were used as sources of OH radicals. To further explore the OH radical scavenger activity of taurine and hypotaurine, their ... The results show that taurine does not scavenge OH radicals nor prevent lipid peroxidation at concentrations up to 20 roM. In ...
Fever Tetramethylpyrazine Antipyresis Hypothalamus Glutamate Hydroxyl radicals Prostaglandin-E2 Responsible Editor: Michael ... All the body core temperature, plasma levels of TNF-α, and hypothalamic levels of glutamate, hydroxyl radicals, and PGE2 were ... Curcumin inhibits the increase of glutamate, hydroxyl radicals and PGE2 in the hypothalamus and reduces fever during LPS- ... An NMDA receptor-dependent hydroxyl radical pathway in the rabbit hypothalamus may mediate lipopolysaccharide fever. ...
Accelerated crystallization of zeolites via hydroxyl free radicals. By Guodong Feng, Peng Cheng, Wenfu Yan, Mercedes Boronat, ... Accelerated crystallization of zeolites via hydroxyl free radicals. By Guodong Feng, Peng Cheng, Wenfu Yan, Mercedes Boronat, ... We report that hydroxyl free radicals (•OH) are involved in the zeolite crystallization under hydrothermal conditions. The ... Hydroxyl radicals generated with ultraviolet light or Fenton reagents can approximately double the rate of zeolite synthesis. ...
... hydroxyl radicals, hyperplasia, in vitro, in vivo, inhalation, irritation, male rats, Metabolism, metered dose inhalers, non ... hydroxyl radicals, impaired spermatogenesis, in vitro, in vivo, inhalation studies, kidneys, limited solubility, lipomas, ...
Apparent hydroxyl radical production by peroxynitrite: implications for endothelial injury from nitric oxide and superoxide.. J ... Apparent hydroxyl radical production by peroxynitrite: implications for endothelial injury from nitric oxide and superoxide. ... Apparent hydroxyl radical production by peroxynitrite: implications for endothelial injury from nitric oxide and superoxide. ... Apparent hydroxyl radical production by peroxynitrite: implications for endothelial injury from nitric oxide and superoxide. ...
The present study addresses the mechanism of hydroxyl radical (·OH) generation by the collapse of microbubbles in water ... Microbubble Methylene blue Degradation Hydroxyl radical pH Ionic strength This is a preview of subscription content, log in to ... Hydroxyl Radical Generation and Contaminant Removal from Water by the Collapse of Microbubbles Under Different Hydrochemical ... Slimane, M., Oualid, H., Yacine, R., & Miloud, G. (2015). Optimum bubble temperature for the production of hydroxyl radical in ...
... the antimicrobial activity of AEW does not depend on these radicals. ... It is strongly suggested that although hydrogen peroxide is present in AEW as a source of hydroxyl radicals, ... Methodology/principal findings: The aim of the present study is to detect hydroxyl radicals in AEW. The hydroxyl radicals in ... The hydroxyl radical, an oxygen radical species, is often suggested as a putative active ingredient for AEW antimicrobial ...
... technology with the benefits of hydroxyl radicals on novel coronavirus (SARS-CoV-2) ... "hydroxyl radicals contained in water". The decisive factor is the existence of hydroxyl radicals inside nanoe™ X. Hydroxyl ... Panasonic: Verification of inhibitory effect of nanoe™ X, technology with the benefits of hydroxyl radicals on novel ... Based on this result, Panasonic announced that "hydroxyl radicals contained in water" technology could be expected to have an ...
Device:"Hydroxyl radicals contained in water" generator. Method:. - "Hydroxyl radicals contained in water" generator is ... Hydroxyl radicals contained in water are particulate ions containing hydroxyl radicals that are generated by applying a high ... A piece of gauze inoculated with the virus solution was placed in a petri dish and exposed to "hydroxyl radicals contained in ... Note: This verification was designed to generate basic research data on the effects of hydroxyl radicals contained in water on ...
A fluorescence assay for the detection of hydrogen peroxide and hydroxyl radicals generated by metallonucleases ... A fluorescence assay for the detection of hydrogen peroxide and hydroxyl radicals generated by metallonucleases S. Leichnitz, J ...
The method utilizes hydroxyl radicals to oxidize solvent accessible sites in macromolecules. In recent years, the method has ... Hydroxyl radical footprinting (HRF) has been successfully used to study the structure of both nucleic acids and proteins. ... Hydroxyl radical footprinting (HRF) has been successfully used to study the structure of both nucleic acids and proteins. The ... Analyzing the structure of macromolecules in their native cellular environment using hydroxyl radical footprinting E. E. Chea ...
Antioxidant activity assessed as inhibition of hydroxyl radical production at 0.5% concentration%. ...
... we synthesized a series of novel hydroxyl chalcone analogs which possessed anti-free radical activity, and screened their ... Compound C7, 4,2-dihydroxy-3,5-dimethoxychalcone was found to have potent activity in these anti-free radical activity tests. ... effects on scavenging 2,2-diphenyl-1-picrylhydrazyl (DPPH) and OH free radicals in vitro. ... pathogenesis involves an imbalance between free radical formation and destruction. In order to obtain a novel preclinical anti- ...
Hydroxyl radical recycling in isoprene oxidation driven by hydrogen bonding and hydrogen tunneling: the upgraded LIM1 mechanism ... Title: Understanding regional oxidation capacity by comprehensive observations to constrain hydroxyl radical sources and sinks ... Final Report: Understanding regional oxidation capacity by comprehensive observations to constrain hydroxyl radical sources and ... HOx radical regeneration in isoprene oxidation via peroxy radical isomerisations. II: experimental evidence and global impact. ...
... released hydroxyl radicals which can damage DNA. Taken together, we conclude that PPD alone and when combined with H2O2 ... leads to the formation of hydroxyl radicals: Oxidative stress and DNA damage in human immortalized keratinocytes Toxicol Lett. ...
With UV light, the optimum temperature for calcination of green tuff powder in order to reduce the hydroxyl radical was also ... The optimum temperature for calcination of the green tuff powder has been investigated in order to produce hydroxyl radicals ... The adsorbed formaldehyde on the green tuff tile and powder was possibility decomposed by the hydroxyl radical produced by ... Production of the Hydroxyl Radical and Removal of Formaldehyde by Calcined Green Tuff Powder and Tile by Toyohisa Fujita 1, ...
Accumulation of the hydroxyl free radical markers meta-, ortho-tyrosine and DOPA in cataractous lenses is accompanied by a ...
... effect of pH on sulfate and hydroxyl radicals. Recently, notable attempts have been devoted to removing emerging pollutants ... The contribution of hydroxyl radical in BTA degradation was boosted at alkaline and neutral conditions especially in the UV/TiO ... effect of pH on sulfate and hydroxyl radicals. 0 ... effect of pH on sulfate and hydroxyl radicals. Be the first to ... Scavenging experiments using alcohols indicated that in acidic pH, the dominant oxidant was sulfate radical in both systems. ...
Production of cold formaldehyde molecules for study and control of chemical reaction dynamics with hydroxyl radicals. Title. ... Production of cold formaldehyde molecules for study and control of chemical reaction dynamics with hydroxyl radicals. ... Production of cold formaldehyde molecules for study and control of chemical reaction dynamics with hydroxyl radicals ...
... and the two free oxygen radicals, namely superoxide radical (•O2−) and hydroxyl radical (OH•), the latter being the most ... 2001) Hydroxyl radical-induced cell-wall loosening in vitro and in vivo: implications for the control of elongation growth. ... Polyamines Interact with Hydroxyl Radicals in Activating Ca2+ and K+ Transport across the Root Epidermal Plasma Membranes. ... 1999) Hydroxyl-radical production in physiological reactions: a novel function of peroxidase. Eur J Biochem 260: 726-735. ...
In other work, research was performed to design a new instrument to measure the hydroxyl radical (OH), which is the most ... Design and Application of Novel Instrumental Techniques in Atmospheric Chemistry: From Gas-Phase Hydroxyl Radical to Levitated ... Design and Application of Novel Instrumental Techniques in Atmospheric Chemistry: From Gas-Phase Hydroxyl Radical to Levitated ...
Generation of hydrogen peroxide, superoxide and hydroxyl radicals during the oxidation of dihydroxyfumaric acid by peroxidase. ... Experiments using scavengers of hydroxyl radicals shown that OH is required. Ability to increase dihydroxyfumarate oxidation is ... Generation of hydrogen peroxide, superoxide and hydroxyl radicals during the oxidation of dihydroxyfumaric acid by peroxidase ... Generation of hydrogen peroxide, superoxide and hydroxyl radicals during the oxidation of dihydroxyfumaric acid by peroxidase ...
Davis, D. D., Ravishankara, A. R., and Fischer, S.: SO2 oxidation via the hydroxyl radical: Atmospheric fate of HSOx radicals, ... Coeur-Tourneur, C., Cassez, A., and Wenger, J. C.: Rate Coefficients for the gas-phase reaction of hydroxyl radicals with 2- ... Rate constant and secondary organic aerosol formation from the gas-phase reaction of eugenol with hydroxyl radicals. Rate ... Rate constant and secondary organic aerosol formation from the gas-phase reaction of eugenol with hydroxyl radicals Rate ...
... is an induced protein and a good scavenger of hydroxyl radical.The ability of MT to scavenge hydroxyl radical stems from ... is an induced protein and a good scavenger of hydroxyl radical.The ability of MT to scavenge hydroxyl radical stems from ... Plant Metallothionein and Its Function in Scavenging Hydroxyl Radical. QUAN Xian-qing,GAO Xiang( Department of Biology,Linyi ... A Comparison of Scavenging Hydroxyl Radical Between Zn_7- and Cd_7-Metallothionein.[J];PROGRESS IN BIOCHEMISTRY AND BIOPHYSICS; ...
This article surveys methods and mechanisms of synthesis and characterization of hydroxytelechelic polymers by the free radical ... Hydroxyl-Terminated Polymers Obtained by Free Radical Polymerization - Synthesis, Characterization, and Applications. ... Hydroxyl-Terminated Polymers Obtained by Free Radical Polymerization - Synthesis, Characterization, and Applications. In: ... Walling, G.: "Free Radicals in Solution", ed. Wiley, J. and sons, London, 48 (1957)Google Scholar ...
  • Yet mere presence of extra oxygen does not tell us whether a given product is generated by a single- (free radical) or two-electron oxidation reaction. (hindawi.com)
  • Peroxynitrite decomposition generates a strong oxidant with reactivity similar to hydroxyl radical, as assessed by the oxidation of deoxyribose or dimethyl sulfoxide. (pnas.org)
  • Pan Y, Chen Y, Li Q, Yu X, Wang J, Zheng J. The Synthesis and Evaluation of Novel Hydroxyl Substituted Chalcone Analogs with in Vitro Anti-Free Radicals Pharmacological Activity and in Vivo Anti-Oxidation Activity in a Free Radical-Injury Alzheimer's Model. (mdpi.com)
  • The kinetics and reaction mechanism for the heterogeneous oxidation of saturated organic aerosols by gas-phase OH radicals were investigated under NO x -free conditions. (atmos-chem-phys.net)
  • Diurnal measurements of hydroxyl and hydroperoxy radicals (OH and HO 2 ) made during the Program for Research on Oxidants: Photochemistry, Emissions, and Transport (PROPHET) summer intensive of 1998 indicate that these key components of gas phase atmospheric oxidation are sustained in significant amounts throughout the night in this northern forested region. (elsevier.com)
  • These reactions consume the hydroxyl radical , which decreases the oxidation potential of the medium [43]. (thefreedictionary.com)
  • Furthermore, it was concluded that, if any visible light absorbing photocatalysts are to be fabricated in future for the purpose of photocatalytic oxidation, their OH radical producing rates (and quantities) should be determined and compared to P25. (st-andrews.ac.uk)
  • 1.1 These test methods cover the Catalyzed Ozone Hydroxyl Radical Oxidation system for the on-line analysis of total nitrogen and total phosphorus in water, wastewater and industrial wastewater. (astm.org)
  • 1.6 The on-line analyses of total nitrogen and total phosphorus, or both, by Catalyzed Ozone Hydroxyl Radical Oxidation technology are utilized in the industry, including applications where total nitrogen and total phosphorus analyses were previously considered to be difficult. (astm.org)
  • The Catalyzed Ozone Hydroxyl Radical Oxidation method is an alternative chemical oxidation method which does not use the traditional oxidation technologies. (astm.org)
  • The total nitrogen and total phosphorus measurement by Catalyzed Ozone Hydroxyl Radical Oxidation method help solve many problems in the industry. (astm.org)
  • This supports oxidation as the key pathway for the post-polymerization decrease in free radical concentration. (theresonance.com)
  • However, although the role of oxidation in the reduction of trapped radicals has gained widespread acceptance, the exact mechanism involved has not yet been described. (theresonance.com)
  • Hydroxyl radicals have the highest oxidation capability amongst all oxygen-based reactive species, thus OH play an important role in oxidation of organic molecules and the bactericidal effects of plasma discharges. (strath.ac.uk)
  • Rate constants of hydroxyl radical oxidation of polychlorinated biphen" by Z Yang, S Luo et al. (ipfw.edu)
  • Oxidation begins with the formation of alkyl radicals, which are formed when the high temperatures and high shear stress experienced during processing snaps the polymer chains in a homolytic manner. (wikipedia.org)
  • It is also an important radical formed in radiation chemistry, since it leads to the formation of hydrogen peroxide and oxygen, which can enhance corrosion and SCC in coolant systems subjected to radioactive environments. (wikipedia.org)
  • Hydroxyl radicals oxidise their protein structures, for example causing protein backbone damage due primarily to a hydrogen abstraction or oxygen addition. (wikipedia.org)
  • Then the presence of hydrogen peroxide as a proposed source of hydroxyl radicals was examined using a combination of ESR and a Fenton reaction. (nih.gov)
  • Since sodium formate, a hydroxyl radical scavenger, did not affect the bactericidal activity of AEW, it is concluded that the radical is unlikely to contribute to the antimicrobial activity of AEW, although a small amount of the radical is produced from hydrogen peroxide. (nih.gov)
  • It is strongly suggested that although hydrogen peroxide is present in AEW as a source of hydroxyl radicals, the antimicrobial activity of AEW does not depend on these radicals. (nih.gov)
  • The optimum temperature for calcination of the green tuff powder has been investigated in order to produce hydroxyl radicals from the decomposition of hydrogen peroxide using ultraviolet light (UV) and no light. (mdpi.com)
  • The homogeneous decomposition of hydrogen peroxide has been used as a source of hydroxyl radicals. (royalsocietypublishing.org)
  • In part I values were reported for the relative rates of reaction of hydroxyl radicals with methane, carbon monoxide, formaldehyde and hydrogen peroxide. (royalsocietypublishing.org)
  • hÿ- droks -ăl) The radical OH, consisting of an oxygen and hydrogen atom bound together. (thefreedictionary.com)
  • However, an optimal hydrogen peroxide concentration exists because overdosing of hydrogen peroxide would lead to a reaction with hydroxyl radical and the formation of H[O. (thefreedictionary.com)
  • In this study the hypothesis that pyrite-induced hydrogen peroxide is transformed to hydroxyl radicals is tested. (duhnnae.com)
  • The addition of EDTA to pyrite slurries inhibits the hydrogen peroxide-to-hydroxyl radical conversion, but does not inhibit the formation of hydrogen peroxide. (duhnnae.com)
  • ConclusionWhile the exact mechanism or mechanisms of the hydrogen peroxide-to-hydroxyl radical conversion cannot be resolved on the basis of the experiments reported in this study, it is clear that the pyrite surface promotes the reaction. (duhnnae.com)
  • In discussing the history of oxidants, such as hydrogen peroxide, respected free radical research pioneer, Barry Halliwell, said that, "In the beginning, it was simple: we said free radicals are bad, antioxidants are good. (ispub.com)
  • Although the production of superoxide, hydrogen peroxide and hypochlorous acid by neutrophils is well established, the endogenous capacity of these cells to generate hydroxyl radical without the addition of a supplemental iron catalyst has not been determined. (umaryland.edu)
  • The hydroxyl radical cuts DNA at every nucleotide, with the amount of cutting proportional to the solvent accessible surface area (SASA) of the deoxyribose hydrogen atoms. (bu.edu)
  • These alkyl radicals react very rapidly with molecular oxygen (rate constants ≈ 107-109 mol-1 s-1) to give peroxy radicals, which in turn abstract hydrogen from a fresh section of polymer in a chain propagation step to give new alkyl radicals. (wikipedia.org)
  • Hydrogen abstraction is usually the rate determining step in the polymer degradation and the peroxy radicals can be scavenged by hydrogen donation from an alternative source, namely the primary antioxidant. (wikipedia.org)
  • In this study, generation of hydroxyl radicals in water by pulsed streamer discharges was investigated. (strath.ac.uk)
  • Fingerprint Dive into the research topics of 'DNase I and hydroxyl radical characterization of chromatin complexes. (elsevier.com)
  • Most notably hydroxyl radicals are produced from the decomposition of hydroperoxides (ROOH) or, in atmospheric chemistry, by the reaction of excited atomic oxygen with water. (wikipedia.org)
  • Hydroxyl radicals are created in the atmosphere by two principal chemical reactions: During daylight hours, a photochemical reaction occurs in the atmosphere where different wavelengths of light interact with water and terpenes (secreted from plants) in the air to produce simpler by-products known as Reactive Oxygen Species (ROS). (wikipedia.org)
  • The rate of reaction with the hydroxyl radical often determines how long many pollutants last in the atmosphere, if they do not undergo photolysis or being rained out. (wikipedia.org)
  • Unlike superoxide, which can be detoxified by superoxide dismutase, the hydroxyl radical cannot be eliminated by an enzymatic reaction. (wikipedia.org)
  • 5,5-Dimethyl-1-pyrroline-N-oxide (DMPO) was used as a spin trapping reagent while the Fenton reaction was used as a source of hydroxyl radical (*OH). (cdc.gov)
  • The Fenton-reaction (Fe(II) + H2O2 Fe(III) + OH + -OH) and the Cr(V)-mediated Fenton-like reaction (Cr(V) + H2O2-Cr(VI) + OH + -OH) were used as sources of OH radicals. (cdc.gov)
  • In contrast, hypotaurine scavenged OH radicals with reaction rate constant of k = 1.6 X 10(10)M-1S-1 and protected against lipid peroxidation in a conccn- tration-dependcnt manner from 0.5-20 mM. (cdc.gov)
  • OH was shown to be produced by the reaction between protons and oxygen radicals generated by the decomposition of O 2 rather than water molecules. (springer.com)
  • Moreover, other scavenging experiments implied that reaction of radicals occurred at both the catalyst surface and in solution. (environmental-expert.com)
  • Both tea flower and tea leaf extracts exert their strong hydroxyl radical scavenging effects in the Fenton reaction system and nitric oxide suppressing effects in LPS-induced RAW 264.7 cells. (unboundmedicine.com)
  • 0.78% v/v. Pretreatment of honeys with catalase prior to their supplementation with Cu ions fully restored bacterial growth indicating that hydroxyl radicals were produced from H(2)O(2) via the Fenton-type reaction. (blogspot.com)
  • The reaction of methyl radicals with oxygen has previously been shown to occur by a third order reaction both at 200 °C (Hoare & Walsh 1957) and at room temperature (Christie 1958). (royalsocietypublishing.org)
  • 7-hydroxycoumarin, the only fluorescent hydroxylation product of this reaction can then be measured to indirectly quantify the OH radicals produced. (st-andrews.ac.uk)
  • No pNDA bleaching was observed for any of the reaction conditions tested after 60 minutes of treatment, which suggests that there was no hydroxyl radical generation during the process. (bioone.org)
  • Free radicals produced during the polymerization reaction become trapped within the substance of the resin. (theresonance.com)
  • The rate constant for the reaction of 4-POBN with {dollar}\alpha{dollar}-hydroxyethyl radical was ten to fifteen fold greater than that with other nitrone spin traps and the resulting spin adduct was stable in the presence of neutrophil secretory products. (umaryland.edu)
  • Based on these findings, it was concluded that human neutrophils and monocytes generate hydroxyl radical through a myeloperoxidase-dependent mechanism which likely involves the reaction of superoxide and hypochlorous acid. (umaryland.edu)
  • Reactions with the hydroxyl radical are a dominant removal pathway for most organic compounds, but experimentally determined gas-phase reaction rate constants are only available for about 750 compounds. (diva-portal.org)
  • The purpose of this paper is to outline how validation and domain definition can facilitate the modeling and prediction of the hydroxyl radical reaction rates for a large database. (diva-portal.org)
  • A QSAR model was developed for the hydroxyl radical reaction rate constant using a projection-based regression technique, PLSR (partial least squares regression). (diva-portal.org)
  • The predicted hydroxyl reaction rates for 25% of these compounds were slow or negligible, with atmospheric half-lives in the range from days to years. (diva-portal.org)
  • Terephthalic acid was used as a chemical probe as this acid is converted into 2-hydroxyterephthalic acid (HTA) by chemical reaction with OH radicals. (strath.ac.uk)
  • Treatment with a series of transition metal chelators did not appreciably alter 4-POBN-CH(CH 3 )OH, which suggested that hydroxyl radical generation was mediated by a mechanism independent of the transition metal- catalyzed Haber-Weiss reaction. (elsevier.com)
  • These findings implicated the reaction of hypochlorous acid and superoxide to produce hydroxyl radical. (elsevier.com)
  • 4-POBN-CH(CH 3 )OH was not observed upon stimulation of myeloperoxidase-deficient neutrophils, whereas addition of myeloperoxidase to the reaction mixture resulted in the detection of hydroxyl radical. (elsevier.com)
  • Moreover, the mechanism for the reaction of the aromatic biogenic p-cymene (4-isopropyl-toluene) with OH radicals was investigated. (uni-bayreuth.de)
  • Hydroxyl radicals are highly reactive (easily becoming hydroxy groups) and consequently short-lived. (wikipedia.org)
  • The decisive factor is the existence of hydroxyl radicals inside nanoe™ X. Hydroxyl radicals are characterized by being strongly oxidative and highly reactive. (businesswire.com)
  • The hydroxyl radical (HO·) is one of the reactive oxygen species (ROS) highly reactive with other molecules to achieve stability. (biomol.com)
  • Since both DCFH and amplex ultrared will react with reactive oxygen species other than hydroxyl radicals and another highly reactive species, peroxynitite, they lack specificity. (biomedcentral.com)
  • The amount of hydroxyl free radicals produced was not quantified, but there is the potential for these highly reactive hydroxyl radicals to damage surrounding tissues on their released from the dental resin. (theresonance.com)
  • Indole-3-propionate reacts with hydroxyl radicals at a diffusion controlled rate and can thereby provide on-site protection against the oxidative damage of biomolecules induced by these highly reactive and toxic oxygen intermediates. (utmb.edu)
  • The main objective of this work was the development of a new analytical tool for the study of heterogeneous hydroxyl radical reactions. (uwaterloo.ca)
  • Studies of the reactions of hydroxyl radicals. (royalsocietypublishing.org)
  • It was found that ascorbic acid is able to suppress reactions involving various α-hydroxyl-containing carbon-centered radicals and depending on the experimental conditions can either oxidize or reduce α-hydroxyethyl radicals. (bsu.by)
  • Although it is occasionally implicated in degradation reactions of artists' materials, hydroxyl radicals have not been studied in depth in the cultural heritage field because of their perceived low concentration at ground level and experimental difficulties in observing the species directly. (gmpca.fr)
  • This disappearance of the free radicals is thought to occur through further reactions with the methacrylate polymer. (theresonance.com)
  • Such reactions are likely to produce more free radicals, indeed, there is evidence supporting the presence of peroxyl free radicals. (theresonance.com)
  • ResultsUsing a combination of electron spin resonance ESR spin-trapping techniques and scavenging reactions involving nucleic acids, the formation of hydroxyl radicals in pyrite-aqueous suspensions is demonstrated. (duhnnae.com)
  • H2O2 and free radicals are produced as a result of certain oxidative reactions involved in the break down of amino acids and fats. (madsci.org)
  • Thus, although both salicylate and D-phenylalanine are useful probes for hydroxyl radical formation in chemical systems, hydroxylated products formed from enzymatic reactions complicate interpretation of data from both compounds in vivo. (uab.edu)
  • The hydroxyl radical is often referred to as the "detergent" of the troposphere because it reacts with many pollutants, decomposing them, often acting as the first step to their removal. (wikipedia.org)
  • For instance methane, which reacts relatively slowly with hydroxyl radicals, has an average lifetime of >5 years and many CFCs have lifetimes of 50 years or more. (wikipedia.org)
  • In the absence of added oxygen, methyl radicals combine to give ethane which in turn reacts with hydroxyl radicals twelve times more rapidly than does methane. (royalsocietypublishing.org)
  • Since hydroxyl radical reacts with biomolecules at diffusion controlled rates, it is important to determine if neutrophils generate this free radical and, if so, establish the mechanism by which it is formed. (umaryland.edu)
  • H2O2 also reacts with the superoxide radical to produce even more reactive free radicals. (madsci.org)
  • we investigated the radical scavenger activity of taurine, and its metabolic precursor hypotaurine (2-arninoethanesulfinic acid). (cdc.gov)
  • To further explore the OH radical scavenger activity of taurine and hypotaurine, their ability to prevent lipid peroxidalion was evaluated using linoleic acid as a model lipid and silica as an occupational source of OH radicals and other oxidants. (cdc.gov)
  • Dimethyl sulfoxide, the other hydroxyl radical scavenger used in the present study, canceled the bactericidal activity of AEW, accompanied by complete depletion of free available chlorine, suggesting that hypochlorous acid is probably a major contributor to the antimicrobial activity. (nih.gov)
  • For this study, we used a simple experimental setup to generate cavitation at a low pressure (low energy) and test it for hydroxyl radical production using a well-known chemical probe as a hydroxyl radical scavenger. (bioone.org)
  • The amount of hydroxyl radicals generated by the system was estimated using N,N -dimethyl-p-nitrosoaniline (pNDA) as hydroxyl radical scavenger. (bioone.org)
  • A model compound, 4-hydroxybenzoic acid (4-HBA), served as a trapping (scavenger) reagent for the determination of hydroxyl radical (OH) concentrations in both systems. (edu.au)
  • Using ABTS, the indole was shown to act as a potent hydroxyl radical scavenger with a rate constant of 7.8 X 10 10 mol l -1 s -1 . (utmb.edu)
  • Hydroxyl radicals have been shown to modify the IgE-binding capacity in pollens, spores and pet dander through the degradation and modification of the tertiary structure and/or the induction of protein denaturation and/or aggregation, resulting in a modified allergen structure. (wikipedia.org)
  • It should be emphasized that, according to the concept of oxidative stress, peroxidation and degradation of vulnerable biological molecules is caused by oxygen-centered radicals generated, in turn, by excessive blood oxygenation. (hindawi.com)
  • The contribution of hydroxyl radical in BTA degradation was boosted at alkaline and neutral conditions especially in the UV/TiO 2 /PMS system. (environmental-expert.com)
  • Mao, Yuxiang 2017-04-03 00:00:00 Singlet oxygen (1O2) and hydroxyl radical (·OH) play an important role in the degradation of pollutants in surface waters. (deepdyve.com)
  • The ability of the catalyst to produce hydroxyl radicals ( · OH) was evaluated by electron paramagnetic resonance measurements using 5,5-dimethyl- 1-pyrroline- N -oxide (DMPO) as spin trap. (springer.com)
  • The success of the basics AOP lies in their ability to produce hydroxyl radicals (H[O. (thefreedictionary.com)
  • The hydroxyl radical has a very short in vivo half-life of approximately 10−9 seconds and a high reactivity. (wikipedia.org)
  • The extreme reactivity of hydroxyl radicals presents challenges to their detection and quantification. (biomedcentral.com)
  • However, recent domestic air quality research has suggested hydroxyl radicals can be generated indoors through the interaction of chemical cleaners with ozone or radiation, and commercial air purifiers are now available that harness the reactivity of hydroxyl radicals to combat odors, molds, and viruses. (gmpca.fr)
  • The EPS of WR-1 presented good flocculating metal chelating and hydroxyl radical scavenging activities while moderate superoxide radical scavenging lipid peroxidation inhibition and lipid emulsification activities were determined. (thefreedictionary.com)
  • These include the superoxide radical O2. (madsci.org)
  • The determination of hydroxyl radical concentrations in environmental chambers using electron spin resonance. (lancs.ac.uk)
  • Optimum bubble temperature for the production of hydroxyl radical in acoustic cavitation-frequency dependence. (springer.com)
  • In this study, we investigate the production of hydroxyl radicals in photo- and electro-catalytic systems. (edu.au)
  • show that the formation of hydroxyl radicals, either by irradiation with ultraviolet light or with the Fenton reagent, can speed up the formation of the crystallized zeolite by about a factor of 2. (sciencemag.org)
  • Alzheimer's disease (AD) pathogenesis involves an imbalance between free radical formation and destruction. (mdpi.com)
  • Neutrophil degranulation inhibits potential hydroxyl-radical formation. (biochemj.org)
  • Hydroxyl radical (.OH) formation by neutrophils in vitro requires exogenous iron. (biochemj.org)
  • Formation of superoxide and hydroxyl radicals from 1-methyl-4-phenylpyridinium ion (MPP+): reductive activation by NADPH cytochrome P-450 reductase. (semanticscholar.org)
  • Formation of free radical intermediates from 1--methyl-4-phenylpyridinium ion(MPP+) has been studied using spin-trapping techniques. (semanticscholar.org)
  • Conclusion: Based on our observations, it may be inferred that moringa extract especially from the fruit (pod) and leaf part has strong antioxidant property as assessed by its property of scavenging hydroxyl radical formation. (eurekaselect.com)
  • Activation of guanylate cyclase by superoxide dismutase and hydroxyl radical: a physiological regulator of guanosine 3',5'-monophosphate formation. (semanticscholar.org)
  • article{Mittal1977ActivationOG, title={Activation of guanylate cyclase by superoxide dismutase and hydroxyl radical: a physiological regulator of guanosine 3',5'-monophosphate formation. (semanticscholar.org)
  • According to Equations (1) and (2), the stage characterizing the start of ozone decomposition may be artificially accelerated by an increase in pH and by compounds that enhance the formation of the hydroxyl radical *OH. (thefreedictionary.com)
  • Inhaled particulate matter can trigger formation of hydroxyl radicals, which have been implicated as one of the causes of particulate-induced lung disease. (biomedcentral.com)
  • The formation of hydroxyl radicals is significant because they react nearly instantaneously with most organic molecules. (duhnnae.com)
  • Hydroxyl radical formation was inhibited by treatment with superoxide dismutase, catalase, and azide. (elsevier.com)
  • Rosen, G. M. / Spin trapping evidence for myeloperoxidase-dependent hydroxyl radical formation by human neutrophils and monocytes . (elsevier.com)
  • Hydroxyl radical-initiated lipid peroxidation, determined by measuring tissue malondialdehyde formation, was inhibited dose-dependently both in vitro and in vivo. (utmb.edu)
  • However, beneficial effects of the great number of phytochemicals that are endowed with hydroxyl radical scavenging and/or iron chelating activities should not be considered as a proof for oxidative stress. (hindawi.com)
  • Reactive oxygen species including hydroxyl radicals can cause oxidative stress and mutations. (biomedcentral.com)
  • A better understanding of the way ROS, including hydroxyl radicals, affect proteins and the conformational changes they induce are crucial to understanding the conditions associated with oxidative stress. (uga.edu)
  • While it remains to be established if endogenous brain tissue levels of indole-3-propionate are sufficiently high to have a significant impact on total antioxidative capacity, the compound itself or a structurally related agent may be useful as an antioxidant adjuvant to combat hydroxyl radical-mediated oxidative stress. (utmb.edu)
  • Using this technique, it was found that human neutrophils and monocytes stimulated with a phorbol ester generated hydroxyl radical. (umaryland.edu)
  • Using the electron spin resonance/spin trapping system, 4-pyridyl 1-oxide N-tert-butylnitrone (4-POBN)/ethanol, hydroxyl radical was detected as the α-hydroxyethyl spin trapped adduct of 4-POBN, 4-POBN-CH(CH 3 )OH, from phorbol 12-myristate 13-acetate-stimulated human neutrophils and monocytes without the addition of supplemental iron. (elsevier.com)
  • These results support the ability of human neutrophils and monocytes to generate hydroxyl radical through a myeloperoxidase-dependent mechanism. (elsevier.com)
  • The use of CIMS allowed for the accurate detection and quantification of hydroxyl radicals. (uwaterloo.ca)
  • The hydroxyl radical can damage virtually all types of macromolecules: carbohydrates, nucleic acids (mutations), lipids (lipid peroxidation), and amino acids (e.g. conversion of phenylalanine to m-tyrosine and o-tyrosine). (wikipedia.org)
  • The results show that taurine does not scavenge OH radicals nor prevent lipid peroxidation at concentrations up to 20 roM. (cdc.gov)
  • The hydroxyl radical scavenging activity of indole-3-propionate was evaluated by kinetic competition studies with the hydroxyl radical trapping reagent 2,2'-azino-bis-(3-ethyl-benz-thiazoline-6-sulfonic acid) (ABTS) and by measuring hydroxyl radical-initiated lipid peroxidation in the rat striatum. (utmb.edu)
  • Efficacy of taurine and hypotaurine as hydroxyl radical scavengers. (cdc.gov)
  • both of which may act as radical scavengers in the cell. (cdc.gov)
  • The rate constant for hypotaurine is comparable with other efficient cellular OH radical scavengers, such as ascorbate and glutathione. (cdc.gov)
  • Experiments using scavengers of hydroxyl radicals shown that OH is required. (biochemj.org)
  • The alkyl radical will typically react rapidly with oxygen forming a peroxy radical. (wikipedia.org)
  • Chemical species including hydroxyl and peroxy radicals (OH and HO(2) + RO(2)), ozone (O(3)), nitrogen oxide (NO), nitric acid (HNO(3)), nitrous acid (HONO), reactive gaseous mercury (RGM), and bromine oxide (BrO) were measured during the campaign. (nerc.ac.uk)
  • the dot identifies the unpaired electron) and the reactive hydroxyl radical (OH. (madsci.org)
  • It was observed that moringa extract scavenges hydroxyl radical at lower concentrations and subsequent increase in concentration suppresses scavenging activity. (eurekaselect.com)
  • Apparent hydroxyl radical production by peroxynitrite: implications for endothelial injury from nitric oxide and superoxide. (pnas.org)
  • Spin-trapping and electron paramagnetic resonance (EPR) spectroscopy have been used to assess the potential release of free radicals from dental resin. (theresonance.com)
  • Kinetic and stability studies were designed to select an appropriate electron paramagnetic resonance/spin trapping system for the detection of hydroxyl radical under biological conditions. (umaryland.edu)
  • The mechanism of PMS activation with/without N-SWCNT and impact of temperature were elucidated by both in situ electron paramagnetic resonance (EPR) technique and selectively radical quenching tests. (edu.au)
  • P25 under UV light produced the highest concentration of OH radicals (16.9 μM), followed by WO3 (0.56 μM) and Pt-C3N4 (0.25 μM). (st-andrews.ac.uk)
  • The concentration of OH radicals was quantified by measuring the fluorescence light intensity generated by HTA molecules in water solutions. (strath.ac.uk)
  • In fact, recent findings from randomized controlled trials (RCTs) have repeatedly failed to support the free radical theory and some trial results have even shown harmful effects and increased risk of mortality from antioxidant use. (ispub.com)
  • The quinone methides of these can rearrange once to give a hydroxycinnamate, regenerating the phenolic antioxidant group and allowing further radicals to be scavenged. (wikipedia.org)
  • Harnessing melanins to scavenge free radicals in vivo may yield treatment methods for inflammatory disorders. (elsevier.com)
  • The present study addresses the mechanism of hydroxyl radical (·OH) generation by the collapse of microbubbles in water solution. (springer.com)
  • The radicals' ability to react with most atmospheric trace gases allows it to act as the main removal mechanism for these gases. (uwaterloo.ca)
  • Here, we present an alternative mechanism based on data demonstrating that polymyxins induce rapid cell death through hydroxyl radical production. (asm.org)
  • Little is known, though, about the detailed chemical mechanism of RNA cleavage by the hydroxyl radical. (jbsdonline.com)
  • These experiments provide the first direct evidence for the mechanism of RNA cleavage by the hydroxyl radical. (jbsdonline.com)
  • However, in steady state models, which include this hypothetical production mechanism, HO 2 radicals are generated in greater quantities than were measured. (elsevier.com)
  • Turchi & Ollis (1990) & Mueses et al (2013) showed that the photocatalytic mechanism more accepted is based on hydroxyl radical attack in the interface semiconductor/solution (Helmholtz layer). (thefreedictionary.com)
  • Furthermore, elucidation of the mechanism underlying melanin-mediated suppression of free radicals, which is yet unclear, is warranted. (elsevier.com)
  • Hayashi, K , Tokuda, A & Sakamoto, W 2018, ' Hydroxyl radical-suppressing mechanism and efficiency of melanin-mimetic nanoparticles ', International journal of molecular sciences , 巻. (elsevier.com)
  • Hydroxyl radicals are also produced during UV-light dissociation of H2O2 (suggested in 1879) and likely in Fenton chemistry, where trace amounts of reduced transition metals catalyze peroxide-mediated oxidations of organic compounds. (wikipedia.org)
  • In organic synthesis, hydroxyl radicals are most commonly generated by photolysis of 1-hydroxy-2(1H)-pyridinethione. (wikipedia.org)
  • The mechanochromic luminescence phenomenon was first reported in the low-cost mechanochemical (MC) synthesis process of a covalent organic framework (COF-TpMA (MC)) prepared using triformylphloroglucinol (Tp) and melamine (MA) as precursors, which shows excellent performance as a hydroxyl radical (˙OH) detector in living systems. (rsc.org)
  • It is postulated that the mass accommodation coefficient, α, for OH radicals on organic surfaces approaches this value under standard atmospheric conditions. (uwaterloo.ca)
  • The hydroxyl radical is known as Nature's Vacuum for its role in "cleaning" Earth's troposphere of organic gases due to its strong oxidizing potential. (gmpca.fr)
  • Electron spin resonance (ESR) in combination with spin trapping techniques was utilized to detect free radicals. (cdc.gov)
  • By contrast, a diet rich in fruits and vegetables and whole grains protects cardiovascular system and lowers blood pressure by reducing free radical stress [ 10 ]. (hindawi.com)
  • The crystallization processes of zeolites-such as Na-A, Na-X, NaZ-21, and silicalite-1-can be accelerated with hydroxyl free radicals generated by ultraviolet irradiation or Fenton's reagent. (sciencemag.org)
  • The influence of gas supply and flow rate, solution pH, and ionic strength on the aeration efficiency, free radical generation, and contaminant removal (take methylene blue as an example) are elucidated. (springer.com)
  • In order to obtain a novel preclinical anti-AD drug candidate, we synthesized a series of novel hydroxyl chalcone analogs which possessed anti-free radical activity, and screened their effects on scavenging 2,2-diphenyl-1-picrylhydrazyl (DPPH) and OH free radicals in vitro . (mdpi.com)
  • Compound C7 , 4,2'-dihydroxy-3,5-dimethoxychalcone was found to have potent activity in these anti-free radical activity tests. (mdpi.com)
  • Accumulation of the hydroxyl free radical markers meta-, ortho-tyrosine and DOPA in cataractous lenses is accompanied by a lower protein and phenyl. (nih.gov)
  • Accumulation of the hydroxyl free radical markers meta-, ortho-tyrosine and DOPA in cataractous lenses is accompanied by a lower protein and phenylalanine content of the water-soluble phase. (nih.gov)
  • This article surveys methods and mechanisms of synthesis and characterization of hydroxytelechelic polymers by the free radical process. (springer.com)
  • The most useful probe evaluated here for hydroxyl radicals formed from cell-free particle suspensions is APF due to its sensitivity and selectivity. (biomedcentral.com)
  • The hydroxyl free radical (OH) is the major oxidizing chemical in the atmosphere, destroying about 3.7 petagrams (Pg) of trace gases each year, including many gases involved in ozone depletion, the greenhouse effect and urban air pollution. (mit.edu)
  • We compared the effects on human and bovine β 2 GPI of °OH free radicals generated by γ -radiolysis of water with 137 Cs and by the Fenton system composed of Fe-EDTA, ascorbate and H 2 O 2 . (biomedcentral.com)
  • The high degree of entanglement of the cross-linked matrix prevents these free radicals from leaving the resin, but their concentration has been shown to reduce overtime until none is detectable. (theresonance.com)
  • These subsequently reacted with the surrounding ethanol molecules to produce secondary ethoxy free radicals. (theresonance.com)
  • The release of free radicals within the mouth could pose an additional safety concern for the use of dental resins. (theresonance.com)
  • It is thus important that further research assesses whether the free radicals from dental resins are released in quantities likely to affect the biocompatibility. (theresonance.com)
  • This detection of free radical release from dental resin provides important new information for understanding the aging process of such resins and highlights a new potential source of concern for the safety of dental resins that warrants further investigation. (theresonance.com)
  • The naïve notion (promulgated by the free radical theory), that EMODs are inherently toxic, is counterintuitive to very basis of the evolutionary concept itself. (ispub.com)
  • Free radicals are molecules that, because they contain an unpaired electron, are extremely reactive. (madsci.org)
  • In recent years the possible relationship between peroxides and free radicals (such as O2. (madsci.org)
  • In addition free radicals can affect the membranes by causing peroxidation of lipids and proteins. (madsci.org)
  • Waruna D. Kulatilaka, Paul S. Hsu, James R. Gord, and Sukesh Roy, "Point and planar ultraviolet excitation/detection of hydroxyl-radical laser-induced fluorescence through long optical fibers," Opt. (osapublishing.org)
  • We demonstrate an all-fiber-coupled, UV, laser-induced-fluorescence (LIF) detection system of the hydroxyl radical (OH) in flames. (osapublishing.org)
  • This study demonstrates high-repetition-rate planar laser-induced fluorescence (PLIF) imaging of hydroxyl radicals (OH) in flames at a continuous framing rate of 50 kHz. (osapublishing.org)
  • In this work, we investigated a series of alkylated benzenes with two to five substituents, using flash photolysis of water vapour for production of OH radicals and resonance fluorescence for their time resolved detection. (uni-bayreuth.de)
  • The internal energy distribution of OH radicals desorbing from a polycrystalline Pt surface at 1130 K was measured by laser-induced fluorescence at pressures near collisionless conditions. (nctu.edu.tw)
  • Publications] Moritake T, Tsuboi K, Anzai K, Ozawa T, Ando K, Nose T: 'ESR spin trapping of hydroxyl radicals in aqueous solution irradiated with high-LET carbon-ion beams. (nii.ac.jp)
  • It has been proposed that plant cell-wall polysaccharides are subject in vivo to non-enzymic scission mediated by hydroxyl radicals ((OH)-O-.). In the present study, xyloglucan was subjected in vitro to partial, non-enzymic scission by treatment with ascorbate plus H2O2, which together generate (OH)-O-.. The partially degraded xyloglucan appeared to contain ester bonds within the backbone, as indicated by an irreversible decrease in viscosity upon alkaline hydrolysis. (ed.ac.uk)
  • Furthermore, in an in vitro system that generated ·OH from FeSO 4 -H 2 O 2 , bromocriptine dose-dependently reduced the number of ·OH radicals. (elsevier.com)
  • Furthermore, in an in vitro system that generated ·OH from FeSO4-H2O2, bromocriptine dose-dependently reduced the number of ·OH radicals. (elsevier.com)
  • see hydroxide hydroxide , chemical compound that contains the hydroxyl (−OH) radical. (thefreedictionary.com)
  • This paper reports the screening of a selection of visible light active photocatalysts such as Pt-C3N4, 5% LaCr doped SrTiO3, Sr0.95Cr0.05TiO3 and Yellow TiO2 and compares them against WO3 and ultra violet (UV) light activated TiO2 P25 (standard commercial catalysts) based on their oxidative strengths (OH radical producing capability) using a well-studied chemical probe − coumarin. (st-andrews.ac.uk)
  • Hydroxylation of salicylate and D-phenylalanine was measured to test the usefulness of these compounds for hydroxyl radical (HȮ) detection in chemical and biological systems. (uab.edu)
  • We expect that these and future results using this experimental system will be useful in developing a more detailed interpretation of RNA structure based on hydroxyl radical cleavage experiments. (jbsdonline.com)
  • Here, we determined the position of eIF1A on the 40S subunit by directed hydroxyl radical cleavage. (bu.edu)
  • OH Radical Cleavage Signatures, or CORCS. (bu.edu)
  • Through the continued analysis of hydroxyl radical cleavage data and development of algorithms to employ the data in biologically meaningful ways, we hope to further our understanding of the relationship between DNA sequence and structure, and how the local structural heterogeneity of genomic DNA contributes to biological function. (bu.edu)
  • They form an important part of radical chemistry. (wikipedia.org)
  • The importance of the hydroxyl radical (OH) to tropospheric chemistry is well known. (uwaterloo.ca)
  • Protein-hydroxyl radical chemistry is also exploited as a biophysical tool to study protein structure, protein folding, protein-protein interactions, and protein-ligand interactions. (uga.edu)
  • An NMDA receptor-dependent hydroxyl radical pathway in the rabbit hypothalamus may mediate lipopolysaccharide fever. (springer.com)
  • In addition, hydroxyl radicals can reduce disulfide bonds in proteins, specifically fibrinogen, resulting in their unfolding and scrambled refolding into abnormal spatial configurations. (hindawi.com)
  • Such radicals acting on DNA could produce mutations, altering the transcrition into mRNA and the translation into proteins. (madsci.org)
  • Hydroxyl radical was not observed upon stimulation of monocyte-derived macrophages and myeloperoxidase-deficient neutrophils. (umaryland.edu)
  • Kinetic differences between transition metal- dependent and -independent mechanisms of hydroxyl radical generation by stimulated neutrophils were demonstrated by a greater rate of 4-POBN- CH(CH 3 )OH accumulation in the presence of supplemental iron. (elsevier.com)
  • Detection of hydroxyl radical from stimulated monocyte-derived macrophages, which lack myeloperoxidase, required the addition of supplemental iron. (elsevier.com)
  • A simple sampling and analytical method for the determination of OH radical concentrations in air is described, as applied to the characterization of air in closed environmental chambers. (lancs.ac.uk)
  • DNase I and hydroxyl radical characterization of chromatin complexes. (elsevier.com)
  • The spin trap 4-pyridyl 1-oxide-N-tert-butylnitrone (4-POBN) in combination with ethanol, in which hydroxyl radical is detected as the {dollar}\alpha{dollar}-hydroxyethyl spin adduct of 4-POBN (4-POBN-CH(CH{dollar}\sb3{dollar})OH), was found to be best suited for this application. (umaryland.edu)
  • Scavenging experiments using alcohols indicated that in acidic pH, the dominant oxidant was sulfate radical in both systems. (environmental-expert.com)
  • Curcumin inhibits the increase of glutamate, hydroxyl radicals and PGE2 in the hypothalamus and reduces fever during LPS-induced systemic inflammation in rabbits. (springer.com)
  • It has been proven that hydroxyl (OH) radicals can be generated by streamer discharges across water surfaces under ambient atmospheric conditions. (strath.ac.uk)
  • Product yields indicative of hydroxyl radical were 5.1 +/- 0.1% and 24.3 +/- 1.0%, respectively, of added peroxynitrite. (pnas.org)
  • A simple method for determining hydroxyl radical yields on semiconductor photocatalysts is highly desirable, especially when comparing different photocatalyst materials. (st-andrews.ac.uk)
  • Osaka, Japan - Panasonic Corporation today announced that, in collaboration with Mayo Yasugi, Associate Professor, Department of Veterinary Science, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, it has verified the inhibitory effect of the hydroxyl radicals contained in water (nano-sized electrostatic atomized water particle) on the novel coronavirus (SARS-CoV-2). (panasonic.com)