Comparative Studies on the Metabolic Hydrogenation of the Ring A in Testosterone and Its Conjugates by Male Rat Liver in Vitro

Metabolic hydrogenation of the ring A double bond in testosterone and its conjugates were studied by incubating 14C-testosterone, 14C-testosterone 17-N-acetylglucosaminide and 3H-testosterone 17-glucosiduronate with 20000×g or 105000×g supernatant fluids and microsomal fraction of male rat liver homogenate under carbon monoxide atmosphere or in air. It was demonstrated that in contrast to testosterone the conjugates were not good substrates for microsomal 4-5α-hydrogenase as well as for hydroxylases, while they were better substrates for soluble 4-5β-hydrogenase than testosterone. These findings are consistent with the observations on in vivo metabolism of testosterone and its conjugates in man.