ESR study on the structure-antioxidant activity relationship of tea catechins and their epimers.
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The purpose of this study is to examine the relationship between the free radical scavenging activities and the chemical structures of tea catechins ((-)-epigallocatechin gallate (EGCG), (-)-epigallocatechin (EGC) and (-)-epicatechin (EC)) and their corresponding epimers ((-)-gallocatechin gallate (GCG), (-)-gallocatechin (GC) and (+)-catechin ((+)-C)). With electron spin resonance (ESR) we investigated their scavenging effects on superoxide anions (O-.2) generated in the irradiated riboflavin system, singlet oxygen(1O2) generated in the photoradiation-hemoporphyrin system, the free radicals generated from 2,2'-azobis(2-amidinopropane)hydrochloride (AAPH) and 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical. The results showed that the scavenging effects of galloylated catechins (EGCG and GCG) on the four free radicals were stronger than those of nongalloylated catechins (EGC, GC, EC, (+)-C), and the scavenging effects of EGC and GC were stronger than those of EC and (+)-C. Thus, it is suggested that the presence of the gallate group at the 3 position plays the most important role in their free radical-scavenging abilities and an additional insertion of the hydroxyl group at the 5' position in the B ring also contributes to their scavenging activities. Moreover, the corresponding phenoxyl radicals formed after the reaction with O-.2 were trapped by DMPO and the ESR spectra of DMPO/phenoxyl radical adducts were observed (aN=15.6 G and aHbeta=21.5 G). No significant differences were found between the scavenging effects of the catechins and their epimers when their concentrations were high. However, significant differences were observed at relatively low concentrations, and the lower their concentrations, the higher the differences. The scavenging abilities of GCG, GC and (+)-C were stronger than those of their corresponding epimers (EGCG, EGC and EC). The differences between their sterical structures played a more important role in their abilities to scavenge large free radicals, such as the free radicals generated from AAPH and the DPPH radical, than to scavenge small free radicals, such as O-.2 and 1O2, especially in the case with EGCG and GCG with more bulky steric hindrance. (+info)
Formation of hydride-Meisenheimer complexes of picric acid (2,4, 6-trinitrophenol) and 2,4-dinitrophenol during mineralization of picric acid by Nocardioides sp. strain CB 22-2.
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There are only a few examples of microbial conversion of picric acid (2,4,6-trinitrophenol). None of the organisms that have been described previously is able to use this compound as a sole source of carbon, nitrogen, and energy at high rates. In this study we isolated and characterized a strain, strain CB 22-2, that was able to use picric acid as a sole source of carbon and energy at concentrations up to 40 mM and at rates of 1.6 mmol. h(-1). g (dry weight) of cells(-1) in continuous cultures and 920 micromol. h(-1). g (dry weight) of cells(-1) in flasks. In addition, this strain was able to use picric acid as a sole source of nitrogen at comparable rates in a nitrogen-free medium. Biochemical characterization and 16S ribosomal DNA analysis revealed that strain CB 22-2 is a Nocardioides sp. strain. High-pressure liquid chromatography and UV-visible light data, the low residual chemical oxygen demand, and the stoichiometric release of 2.9 +/- 0.1 mol of nitrite per mol of picric acid provided strong evidence that complete mineralization of picric acid occurred. During transformation, the metabolites detected in the culture supernatant were the [H-]-Meisenheimer complexes of picric acid and 2,4-dinitrophenol (H--DNP), as well as 2,4-dinitrophenol. Experiments performed with crude extracts revealed that H--DNP formation indeed is a physiologically relevant step in picric acid metabolism. (+info)
Function of coenzyme F420 in aerobic catabolism of 2,4, 6-trinitrophenol and 2,4-dinitrophenol by Nocardioides simplex FJ2-1A.
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2,4,6-Trinitrophenol (picric acid) and 2,4-dinitrophenol were readily biodegraded by the strain Nocardioides simplex FJ2-1A. Aerobic bacterial degradation of these pi-electron-deficient aromatic compounds is initiated by hydrogenation at the aromatic ring. A two-component enzyme system was identified which catalyzes hydride transfer to picric acid and 2,4-dinitrophenol. Enzymatic activity was dependent on NADPH and coenzyme F420. The latter could be replaced by an authentic preparation of coenzyme F420 from Methanobacterium thermoautotrophicum. One of the protein components functions as a NADPH-dependent F420 reductase. A second component is a hydride transferase which transfers hydride from reduced coenzyme F420 to the aromatic system of the nitrophenols. The N-terminal sequence of the F420 reductase showed high homology with an F420-dependent NADP reductase found in archaea. In contrast, no N-terminal similarity to any known protein was found for the hydride-transferring enzyme. (+info)
Fucoxanthin as the major antioxidant in Hijikia fusiformis, a common edible seaweed.
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The radical scavenging activity of Japanese edible seaweeds was screened by the DPPH (1-diphenyl-2-picrylhydrazyl) assay to evaluate the DPPH radical scavenging activity in organic extracts. The fresh brown alga Hijikia fusiformis showed the strongest DPPH radical scavenging activity, followed by Undaria pinnatifida and Sargassum fulvellum. The major active compound from Hijikia fusiformis in its acetone extract was identified as fucoxanthin by 13C-NMR spectroscopy. (+info)
Dehydroepiandrosterone sulphate promotes hyaluronic acid-induced cervical ripening in rabbits.
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Hyaluronic acid (HA) stimulates the synthesis of interleukin (IL) 8, while dehydroepiandrosterone sulphate (DHEA-S) induces the expression of IL-8 and its receptor in the human cervical fibroblast. This has led us to investigate the effect of DHEA-S on HA-induced cervical ripening. Experiments were performed in pregnant rabbits using vaginal suppositories containing 1 mg HA, 30 mg DHEA-S, 30 mg DHEA-S + 0.1 mg HA, 30 mg DHEA-S + 1 mg HA, and 500 microl Witepsol-50 base (control). The effects were evaluated by measuring collagenase, gelatinase and elastase activities, water content, neutrophil infiltration, relative collagen concentration and histological assessment. The activities of collagenase, gelatinase and elastase were significantly increased in rabbits treated with DHEA-S + 1 mg HA compared with rabbits treated with DHEA-S + 0.1 mg HA (P < 0.009, P < 0.001, P < 0.009 respectively). Water content was markedly increased in rabbits treated with DHEA-S + 1 mg HA compared with DHEA-S + 0.1 mg HA treatment (P < 0.05). Neutrophil infiltration was markedly increased, while relative collagen concentration was significantly decreased with DHEA-S + 1 mg HA compared with the DHEA-S + 0.1 mg HA approach (P < 0.001, P < 0.002). The histology of cervices treated with DHEA-S + 1 mg HA showed the density of collagen to be markedly decreased, and collagen fibres irregularly separated. Increased vascularity with massive dilatation of blood vessels was also observed in these rabbits. We conclude that DHEA-S upregulates the HA-induced cervical ripening process. (+info)
Glomerular filtration rate estimation from plasma creatinine after inhibition of tubular secretion: relevance of the creatinine assay.
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BACKGROUND: Estimation of glomerular filtration rate (GFR) from plasma creatinine concentration after inhibition of tubular creatinine secretion with cimetidine provides a good assessment in patients with various nephropathies and with non-insulin-dependent diabetes mellitus (NIDDM). The aim of this study was to compare cimetidine-aided GFR estimations using various creatinine assays. METHODS: In 30 outpatients with NIDDM GFR was measured as the urinary clearance of continuously infused [125I]iothalamate. Plasma creatinine concentration was analysed after oral cimetidine with an alkaline picrate (AP) method, with an enzymatic (PAP) assay and with HPLC. GFR estimations were calculated with the Cockcroft Gault formula (CG). RESULTS: AP creatinine concentrations were significantly higher than PAP or HPLC values. GFR estimations by AP (CG(AP) 66 +/- 19 ml/min/1.73 m2, mean SD) were significantly lower than GFR (89 +/- 30), whereas CG(PAP) (85 +/- 30) and CG(HPLC) (84 +/- 34 ml/min/1.73 m2) were not. Bland and Altman analysis showed a difference between CG(AP) and GFR of -22.4 +/- 17.7 ml/min/1.73 m2; this difference becomes larger when the GFR increases. The difference between CG and GFR was only -3.8 +/- 14.8 ml/min/1.73 m2 for PAP and -4.4 +/- 17.5 ml/min/1.73 m2 for HPLC, without any systematic difference. CONCLUSION: A good assessment of the GFR from plasma creatinine after cimetidine administration is possible when creatinine is measured with an enzymatic assay or with the less convenient HPLC method. The more widespread and cheaper alkaline picrate assay is not suitable for GFR-estimation. (+info)
Cutting edge: CD40 ligand is a limiting factor in the humoral response to T cell-dependent antigens.
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CD40 ligand (CD40L) plays a crucial role in T cell-dependent B cell responses, but whether its abundance is a limiting factor in their development is unclear. This question was addressed in transgenic mice expressing the murine CD40L gene under the control of the IL-2-promoter (CD40Ltg+). The fraction of activated T cells from the CD40Ltg+ mice with detectable levels of surface CD40L was modestly greater (1.1- to 2-fold) than littermate controls and paralleled an approximately 1.8-fold increase in CD40L mRNA abundance. In response to trinitrophenol (TNP)-keyhole limpet hemocyanin and tetanus/diphtheria vaccine, CD40Ltg+ mice developed higher titers of high-affinity IgG and IgG1 Ab than wild-type mice. In contrast, the Ab response of CD40Ltg+ and control mice was similar in response to the T-independent Ag TNP-Ficoll. These results suggest that a modest increment in expression of CD40L accelerates the development of T-dependent responses, and that CD40L plays a limiting role in the induction of high-affinity Ab and Ab-class switching. (+info)
Radical scavenging activity of phenylpropanoid glycosides in Caryopteris incana.
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In our screening program for antioxidants from traditional drugs and foodstuffs, one new phenylpropanoid glycoside, incanoside, was isolated together with four known phenylpropanoid glycosides, verbascoside, isoverbascoside, phlinoside A, and 6-O-caffeoyl-beta-D-glucose from the whole plant of Caryopteris incana (Thunb.) Miq. On the basis of chemical evidence and spectral analysis data, the structure of incanoside was determined to be 1-O-(3,4-dihydroxyphenyl)ethyl-O-beta-D-glucopyranosyl (1-->2)-alpha-L-rhamnopyranosyl(1-->3)-6-O-caffeoyl-beta-D- glucopyranoside. The four phenylpropanoid glycosides exhibited potent radical scavenging activity against DPPH, hydroxyl (.OH), and superoxide anion (O2-.) radicals. (+info)