Steroid Structure and Androgenicity

Abstract

Fifteen derivatives of androstane were compared with testosterone for their androgenic effects on the cockerel comb or the levator ani, seminal vesicle and ventral prostate of immature castrated male rats. The ventral prostate response was a more sensitive end-point for testosterone than the seminal vesicle, while the levator ani response was the least senstive. The cockerel comb response was generally found to parallel that of the rat ventral prostate. In rat bio-assays, testosterone was about 100 times more effective administered parenterally than orally. The presence of a 17β-hydroxyl group was shown to be necessary for maximal androgenic activity regardless of the type of end-point observed. The 17-ketone group was found to be somewhat less active than 17β-hydroxyl in cockerel comb or ventral prostate bio-assays, while the seminal vesicle and levator ani responses were greatly decreased. 5β-Androstanes were invariably much less androgenic than the A4 or 5 a compounds, regardless of the nature of substitution on positions 3 or 17, the route of administration or the bio-assay end-points employed. Removal of the 3-oxy function, as in the 3-desoxy-5a or Δ⁴-17β-ol derivatives, results in compounds which either equal or exceed testosterone in androgenicity after oral administration but are less active than testosterone when both are given parenterally. A low level of androgenicity was demonstrated for the hydrocarbons 5 a- and 5β-androstane and Δ⁴-androstene in the cockerel comb and the rat bio-assays. Because these hydrocarbons are more effective if given orally than parenterally to rats, they are probably proandrogens.