Testosterone oxidation by rat liver microsomes: Effects of phenobarbital pretreatment and the detection of seven metabolites by HPLC

The oxidation products of testosterone catalyzed by microsomes from untreated and phenobarbital pretreated adult male rats have been analyzed by reverse-phase high performance liquid chromatography (HPLC). The major products formed by control microsomes are 2α- and 16α-hydroxytestosterone followed by and drostenedione, 6β- and 7α- and negligible quantities of 2β- and 16β-hydroxytestosterone. The hydroxylation of testosterone at carbon-2 yields mainly 2α- and not 2β-hydroxytestosterone. Pretreatment with phenobarbital resulted in a qualitatively similar but quantitatively different metabolite pattern. Specifically, the formation of 2β-, 6β-, 7α- and 16β-hydroxytestosterone is increased whereas that of 2α- and 16α-hydroxytestosterone is decreased.