Abstract
Summary and Conclusions
(1) The biological activity of ethinylandrostanediol and its Δ 5 -analog has been found to be predominantly estrogenic rather than androgenic. The relative testicular growth suppressing (TGSp) activity effected by these ethinyl-diols was considerably greater than observed for equivalent estrogenic doses of estradiol-17β or ethinylestradiol. (2) Low molecular weight esters (less than 6 carbon atoms) of these non-phenolic steroids were more active than their parent alcohols, but the degree of estrogenicity (UGSt) diminished more abruptly than did TGSp activity as the size of the ester group was increased. Of the compounds tested, the 3a-ethylbutyrate of ethinyl-Δ 5 -androstenediol effected the greatest degree of testicular growth suppression (TGSp) per unit of estrogenicity (UGSt-ED50), when 35-40 gram immature in tacts rats were used.
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