Chloroethanes : their metabolism by hepatic cytochrome P-450 in vitro. 1981

K M Ivanetich, and L H Van den Honert

1,1,1- and 1,1,2-trichloroethane and 1,1,2,3-tetrachloroethane stimulate CO- inhibitable NADPH oxidation by hepatic microsomes. Incubation of the chloroethanes, hepatic microsomes, an NADPH-generating system and EDTA results in the production of chlorinated metabolites. Both NADPH oxidation and metabolite production are inhibited by CO, SKF 525A and/or metyrapone The induction of cytochrome P-450 with phenobarbital enhances the binding and metabolism of the chloroalkanes, while the induction of cytochrome P-448 with beta-naphthoflavone does not. 1,1,1-trichloroethane is converted to 2,2,2-trichloroethanol by hepatic microsomal cytochrome P-450, while the major metabolites of 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane from this enzyme system are mono- and dichloroacetate, respectively. Mechanisms for the production of these metabolites are suggested. The relative mutagenic and carcinogenic potentials of the three chloroethanes are considered with respect to their relative extents of metabolism and their proposed metabolic pathways.

UI MeSH Term Description Entries
D007700 Kinetics The rate dynamics in chemical or physical systems.
D008297 Male Males
D008862 Microsomes, Liver Closed vesicles of fragmented endoplasmic reticulum created when liver cells or tissue are disrupted by homogenization. They may be smooth or rough. Liver Microsomes,Liver Microsome,Microsome, Liver
D009249 NADP Nicotinamide adenine dinucleotide phosphate. A coenzyme composed of ribosylnicotinamide 5'-phosphate (NMN) coupled by pyrophosphate linkage to the 5'-phosphate adenosine 2',5'-bisphosphate. It serves as an electron carrier in a number of reactions, being alternately oxidized (NADP+) and reduced (NADPH). (Dorland, 27th ed) Coenzyme II,Nicotinamide-Adenine Dinucleotide Phosphate,Triphosphopyridine Nucleotide,NADPH,Dinucleotide Phosphate, Nicotinamide-Adenine,Nicotinamide Adenine Dinucleotide Phosphate,Nucleotide, Triphosphopyridine,Phosphate, Nicotinamide-Adenine Dinucleotide
D010084 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). Redox,Oxidation Reduction
D003577 Cytochrome P-450 Enzyme System A superfamily of hundreds of closely related HEMEPROTEINS found throughout the phylogenetic spectrum, from animals, plants, fungi, to bacteria. They include numerous complex monooxygenases (MIXED FUNCTION OXYGENASES). In animals, these P-450 enzymes serve two major functions: (1) biosynthesis of steroids, fatty acids, and bile acids; (2) metabolism of endogenous and a wide variety of exogenous substrates, such as toxins and drugs (BIOTRANSFORMATION). They are classified, according to their sequence similarities rather than functions, into CYP gene families (>40% homology) and subfamilies (>59% homology). For example, enzymes from the CYP1, CYP2, and CYP3 gene families are responsible for most drug metabolism. Cytochrome P-450,Cytochrome P-450 Enzyme,Cytochrome P-450-Dependent Monooxygenase,P-450 Enzyme,P450 Enzyme,CYP450 Family,CYP450 Superfamily,Cytochrome P-450 Enzymes,Cytochrome P-450 Families,Cytochrome P-450 Monooxygenase,Cytochrome P-450 Oxygenase,Cytochrome P-450 Superfamily,Cytochrome P450,Cytochrome P450 Superfamily,Cytochrome p450 Families,P-450 Enzymes,P450 Enzymes,Cytochrome P 450,Cytochrome P 450 Dependent Monooxygenase,Cytochrome P 450 Enzyme,Cytochrome P 450 Enzyme System,Cytochrome P 450 Enzymes,Cytochrome P 450 Families,Cytochrome P 450 Monooxygenase,Cytochrome P 450 Oxygenase,Cytochrome P 450 Superfamily,Enzyme, Cytochrome P-450,Enzyme, P-450,Enzyme, P450,Enzymes, Cytochrome P-450,Enzymes, P-450,Enzymes, P450,Monooxygenase, Cytochrome P-450,Monooxygenase, Cytochrome P-450-Dependent,P 450 Enzyme,P 450 Enzymes,P-450 Enzyme, Cytochrome,P-450 Enzymes, Cytochrome,Superfamily, CYP450,Superfamily, Cytochrome P-450,Superfamily, Cytochrome P450
D004980 Ethane A two carbon alkane with the formula H3C-CH3.
D006843 Hydrocarbons, Chlorinated Hydrocarbon compounds with one or more of the hydrogens replaced by CHLORINE. Chlorinated Hydrocarbon,Chlorinated Hydrocarbons,Organochlorine Compound,Chlorine Compounds, Organic,Organochlorine Compounds,Compound, Organochlorine,Compounds, Organic Chlorine,Compounds, Organochlorine,Hydrocarbon, Chlorinated,Organic Chlorine Compounds
D006861 Hydrogen Peroxide 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. Hydrogen Peroxide (H2O2),Hydroperoxide,Oxydol,Perhydrol,Superoxol,Peroxide, Hydrogen
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia

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