HydroquinonesBenzene: Toxic, volatile, flammable liquid hydrocarbon byproduct of coal distillation. It is used as an industrial solvent in paints, varnishes, lacquer thinners, gasoline, etc. Benzene causes central nervous system damage acutely and bone marrow damage chronically and is carcinogenic. It was formerly used as parasiticide.ArbutinBenzoquinones: Benzene rings which contain two ketone moieties in any position. They can be substituted in any position except at the ketone groups.Phenol: An antiseptic and disinfectant aromatic alcohol.Skin Lightening Preparations: Substances used to obtain a lighter skin complexion or to treat HYPERPIGMENTATION disorders.NAD(P)H Dehydrogenase (Quinone): A flavoprotein that reversibly catalyzes the oxidation of NADH or NADPH by various quinones and oxidation-reduction dyes. The enzyme is inhibited by dicoumarol, capsaicin, and caffeine.Flavodoxin: A low-molecular-weight (16,000) iron-free flavoprotein containing one molecule of flavin mononucleotide (FMN) and isolated from bacteria grown on an iron-deficient medium. It can replace ferredoxin in all the electron-transfer functions in which the latter is known to serve in bacterial cells.Catechols: A group of 1,2-benzenediols that contain the general formula R-C6H5O2.Bleaching Agents: Chemicals that are used to oxidize pigments and thus effect whitening.Hyperpigmentation: Excessive pigmentation of the skin, usually as a result of increased epidermal or dermal melanin pigmentation, hypermelanosis. Hyperpigmentation can be localized or generalized. The condition may arise from exposure to light, chemicals or other substances, or from a primary metabolic imbalance.Hydroxocobalamin: Injectable form of VITAMIN B 12 that has been used therapeutically to treat VITAMIN B 12 DEFICIENCY.Oxidation-Reduction: 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).Phenols: Benzene derivatives that include one or more hydroxyl groups attached to the ring structure.Quinones: Hydrocarbon rings which contain two ketone moieties in any position. They can be substituted in any position except at the ketone groups.Melanosis: Disorders of increased melanin pigmentation that develop without preceding inflammatory disease.Dicumarol: An oral anticoagulant that interferes with the metabolism of vitamin K. It is also used in biochemical experiments as an inhibitor of reductases.Photinia: A plant genus of the family ROSACEAE. The common names of chokeberry or chokecherry are also used for some species of PRUNUS.Mutagens: Chemical agents that increase the rate of genetic mutation by interfering with the function of nucleic acids. A clastogen is a specific mutagen that causes breaks in chromosomes.Ochronosis: The yellowish discoloration of connective tissue due to deposition of HOMOGENTISIC ACID (a brown-black pigment). This is due to defects in the metabolism of PHENYLALANINE and TYROSINE. Ochronosis occurs in ALKAPTONURIA, but has also been associated with exposure to certain chemicals (e.g., PHENOL, trinitrophenol, BENZENE DERIVATIVES).Pyronine: Xanthene dye used as a bacterial and biological stain. Synonyms: Pyronin; Pyronine G; Pyronine Y. Use also for Pyronine B. which is diethyl-rather than dimethylamino-.Sorbic Acid: Mold and yeast inhibitor. Used as a fungistatic agent for foods, especially cheeses.Carbon-Carbon Ligases: Enzymes that catalyze the joining of two molecules by the formation of a carbon-carbon bond. These are the carboxylating enzymes and are mostly biotinyl-proteins. EC 6.4.Parabens: Methyl, propyl, butyl, and ethyl esters of p-hydroxybenzoic acid. They have been approved by the FDA as antimicrobial agents for foods and pharmaceuticals. (From Hawley's Condensed Chemical Dictionary, 11th ed, p872)Dysidea: A genus of SPONGES in the family Dysideidae, in which all skeletal fibers are filled with detritus.Pleurotus: A genus of basidiomycetous fungi, family POLYPORACEAE, order POLYPORALES, that grows on logs or tree stumps in shelflike layers. The species P. ostreatus, the oyster mushroom, is a choice edible species and is the most frequently encountered member of the genus in eastern North America. (Alexopoulos et al., Introductory Mycology, 4th ed, p531)Chlorophenols: Phenols substituted with one or more chlorine atoms in any position.Vitamin K 1: A family of phylloquinones that contains a ring of 2-methyl-1,4-naphthoquinone and an isoprenoid side chain. Members of this group of vitamin K 1 have only one double bond on the proximal isoprene unit. Rich sources of vitamin K 1 include green plants, algae, and photosynthetic bacteria. Vitamin K1 has antihemorrhagic and prothrombogenic activity.Sphingomonas: A genus of gram-negative, aerobic, rod-shaped bacteria characterized by an outer membrane that contains glycosphingolipids but lacks lipopolysaccharide. They have the ability to degrade a broad range of substituted aromatic compounds.Naphthoquinones: Naphthalene rings which contain two ketone moieties in any position. They can be substituted in any position except at the ketone groups.Desulfitobacterium: A genus of anaerobic, gram-positive bacteria in the family Peptococcaceae, that reductively dechlorinates CHLOROPHENOLS.Pentachlorophenol: An insecticide and herbicide that has also been used as a wood preservative. Pentachlorphenol is a widespread environmental pollutant. Both chronic and acute pentachlorophenol poisoning are medical concerns. The range of its biological actions is still being actively explored, but it is clearly a potent enzyme inhibitor and has been used as such as an experimental tool.Veillonellaceae: A family of gram-negative bacteria, in the phylum FIRMICUTES.Biotransformation: The chemical alteration of an exogenous substance by or in a biological system. The alteration may inactivate the compound or it may result in the production of an active metabolite of an inactive parent compound. The alterations may be divided into METABOLIC DETOXICATION, PHASE I and METABOLIC DETOXICATION, PHASE II.Rifabutin: A broad-spectrum antibiotic that is being used as prophylaxis against disseminated Mycobacterium avium complex infection in HIV-positive patients.Anisoles: A group of compounds that are derivatives of methoxybenzene and contain the general formula R-C7H7O.Facial DermatosesVitamin K: A lipid cofactor that is required for normal blood clotting. Several forms of vitamin K have been identified: VITAMIN K 1 (phytomenadione) derived from plants, VITAMIN K 2 (menaquinone) from bacteria, and synthetic naphthoquinone provitamins, VITAMIN K 3 (menadione). Vitamin K 3 provitamins, after being alkylated in vivo, exhibit the antifibrinolytic activity of vitamin K. Green leafy vegetables, liver, cheese, butter, and egg yolk are good sources of vitamin K.Bromates: Negative ions or salts derived from bromic acid, HBrO3.MaleatesQuinone Reductases: NAD(P)H:(quinone acceptor) oxidoreductases. A family that includes three enzymes which are distinguished by their sensitivity to various inhibitors. EC 18.104.22.168 (NAD(P)H DEHYDROGENASE (QUINONE);) is a flavoprotein which reduces various quinones in the presence of NADH or NADPH and is inhibited by dicoumarol. EC 22.214.171.124 (NADH dehydrogenase (quinone)) requires NADH, is inhibited by AMP and 2,4-dinitrophenol but not by dicoumarol or folic acid derivatives. EC 126.96.36.199 (NADPH dehydrogenase (quinone)) requires NADPH and is inhibited by dicoumarol and folic acid derivatives but not by 2,4-dinitrophenol.Molecular Structure: 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.Mixed Function Oxygenases: Widely distributed enzymes that carry out oxidation-reduction reactions in which one atom of the oxygen molecule is incorporated into the organic substrate; the other oxygen atom is reduced and combined with hydrogen ions to form water. They are also known as monooxygenases or hydroxylases. These reactions require two substrates as reductants for each of the two oxygen atoms. There are different classes of monooxygenases depending on the type of hydrogen-providing cosubstrate (COENZYMES) required in the mixed-function oxidation.Electron-Transferring Flavoproteins: Flavoproteins that serve as specific electron acceptors for a variety of DEHYDROGENASES. They participate in the transfer of electrons to a variety of redox acceptors that occur in the respiratory chain.