Microsomal metabolism of thiobenzamide and thiobenzamide S-oxide. 1983

R P Hanzlik, and J R Cashman

The oxidation of [3H]thiobenzamide (TB) and its S-oxide (TBSO) has been investigated using rat liver microsomes. In the presence of O2 and NADPH, TB is rapidly converted to TBSO plus small amounts of benzamide (BA) by rat liver microsomes; neither benzonitrile nor other metabolites were detected. Under similar conditions, TBSO is converted solely to BA. Studies with metabolic inhibitors and inducing agents indicated that both the S-oxidation of TB and its further conversion to BA, probably via enzymatic oxidation to TBSO2 (a chemically reactive sulfene), are catalyzed mainly by the microsomal FAD-containing monooxygenase. No clear evidence for the involvement of cytochromes P-450 was obtained, but neither could this possibility be excluded. The overall pathway for biotransformation of TB in vitro can be represented as: TB leads to TBSO leads to [TBSO2] leads to BA. The possible role of TBSO and TBSO2 in the in vivo hepatotoxicity of TB and TBSO are discussed in light of their chemical reactivities.

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
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
D010634 Phenobarbital A barbituric acid derivative that acts as a nonselective central nervous system depressant. It potentiates GAMMA-AMINOBUTYRIC ACID action on GABA-A RECEPTORS, and modulates chloride currents through receptor channels. It also inhibits glutamate induced depolarizations. Phenemal,Phenobarbitone,Phenylbarbital,Gardenal,Hysteps,Luminal,Phenobarbital Sodium,Phenobarbital, Monosodium Salt,Phenylethylbarbituric Acid,Acid, Phenylethylbarbituric,Monosodium Salt Phenobarbital,Sodium, Phenobarbital
D011919 Rats, Inbred Strains Genetically identical individuals developed from brother and sister matings which have been carried out for twenty or more generations or by parent x offspring matings carried out with certain restrictions. This also includes animals with a long history of closed colony breeding. August Rats,Inbred Rat Strains,Inbred Strain of Rat,Inbred Strain of Rats,Inbred Strains of Rats,Rat, Inbred Strain,August Rat,Inbred Rat Strain,Inbred Strain Rat,Inbred Strain Rats,Inbred Strains Rat,Inbred Strains Rats,Rat Inbred Strain,Rat Inbred Strains,Rat Strain, Inbred,Rat Strains, Inbred,Rat, August,Rat, Inbred Strains,Rats Inbred Strain,Rats Inbred Strains,Rats, August,Rats, Inbred Strain,Strain Rat, Inbred,Strain Rats, Inbred,Strain, Inbred Rat,Strains, Inbred Rat
D000577 Amides Organic compounds containing the -CO-NH2 radical. Amides are derived from acids by replacement of -OH by -NH2 or from ammonia by the replacement of H by an acyl group. (From Grant & Hackh's Chemical Dictionary, 5th ed) Amide
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
D001713 Biphenyl Compounds Whitish aromatic crystalline organic compounds made up of two conjoined BENZENE rings. Compounds, Biphenyl
D013854 Thioamides Organic compounds containing the radical -CSNH2. Thioamide

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