Abstract
In vitro metabolism of 3H-testosterone 17-sulfate (3H-TS) and 14C-testosterone 17-tetrahydropyranyl ether (14C-TP) was studied by incubation with 20000×g or 105000×g supernatant and microsomal fractions of male rat liver homogenate under carbon monoxide atmosphere or in air. The results demonstrated that the steroidal ring A of 3H-TS was readily metabolized by microsomal Δ4-5α-hydrogenase, while 14C-TP was a good substrate for 4-5α-hydrogenase present in the 105000×g supernatant fraction as well as microsomal Δ4-5α-hydrogenase. On the other hand, 3H-TS and 14C-TP were not good substrates for microsomal hydroxylases. The influence of the substituent at C-17 of testosterone upon the biotransformation of ring A was discussed.
