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The appearance of intermediates and products in the transformation of 4-androstene-3,17-dione and testosterone to estrone and 17β-estradiol by human placental microsomes was studied. The variables investigated were time, temperature and the concentrations of reduced pyridine nucleotides and of testosterone. The relative amounts of metabolites were markedly influenced by all of the factors studied except temperature, although the reaction velocity at 37 °C was about twice that at 27 °C. Oxidoreduction at C-17 in starting material, intermediates and products was examined using a mixture of [4-14C]testosterone and [7β,17α-²H2]testosterone as substrate. Oxidation and reduction at C-17 was most prominent at the beginning and the end of the reaction sequence. 17α-Hydroxy-5α-androst-1-en-3-one was found to be an inhibitor of the C19 17β-hydroxysteroid dehydrogenase activity of human placental microsomes. [ABSTRACT FROM AUTHOR]

The metabolism of testosterone in human foetal adrenal glands at mid-gestation was investigated in vitro. After incubations with microsome preparations in a medium supplemented with NADPH-regenerating system, the metabolites were isolated by thin-layer and gas-liquid chromatography, and identified by gas chromatography-mass spectrometry. 4-Androstenedione, 3β-hydroxy-4-androsten-17-one and 4-androstene-3α (and 3β),17β-diols were identified in both incubation series. The presence of 1β-, 2α-, 2β-, 6α- and 6β-hydroxylase activities in foetal adrenal glands was demonstrated by the isolation of the corresponding testosterone derivatives. The biosynthesis of these steroids in human adrenal gland has not been demonstrated before. Because 3β-hydroxy-4-androsten-17-one and epimeric 4-androstene-3α (and 3β),17β-diols could be isolated in these incubation studies the presence of 3α, 3β- and 17β-hydroxysteroid oxidoreductase in the adrenal gland preparation is very likely. Neither 5α(H)- nor 5β(H)-ring reductase activities have been detected. [ABSTRACT FROM AUTHOR]