Inhibition of testosterone 5α-reductase by and antiandrogenicity of allenic 3-keto-5,10-secosteroids

W. Voigt, A. Castro, D. F. Covey, C. H. Robinson

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(4R)-5,10-seco-19-norpregna-4,5-diene-3,10,20-trione(II), a 3-keto-5,10-secosteroid which is an irreversible inhibitor of Δ5-3-ketosteroid isomerase was tested for its possible antiandrogenicity in the hamster flank organ test. The organs of female animals topically treated with 4 μg of testosterone propionate (TP) for 4 weeks enlarged in size and showed pigmentation resembling adult males. When compound II was applied concomitantly with TP, androgenic stimulation was completely blocked and the flank organs remained small like those of female animals. These results suggest that compound II may be a useful anti-androgen when applied topically. It may well act mainly by inhibition of the formation of 5α-reduced metabolites of testosterone, as judged by its effect on rat prostatic 5α-reductase. Thus, incubation of a rat prostatic homogenate with [4-14C]testosterone produced 5α-dihydrotestosterone and 5α- androstane-3α,17β-diol as the main products. However, when compound II was included in the incubation mixture, the production of these 5α-reduced metabolites was markedly inhibited.

Original languageEnglish
Pages (from-to)668-672
Number of pages5
JournalActa Endocrinologica
Issue number3
StatePublished - 1978


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