Comparative evaluation of the dissociation rate between the vaginotrophic and uterotrphic activities of 1-hydroxy-1, 3, 5 (10)-estratriene derivatives with natural and unnatural configuration at C8 using ovariectomized mice.

Influences on estrogenic.activities of 1-hydroxylation and C8-isomerization in the molecules of naturally occurring estrogens have been studied. All compounds tested behaved qualitatively in the same manner as estradiol, as far as the decrease in the vaginal and uterine sialic acid levels and the increase in the organ weights of the vagina and uterus of castrated mice are concerned. They were, however, different not only in the relative ptoencies of the estrogenic effects, but also in the dissociation rate between the vaginotrphic and uterotrophic activities. Of the compounds tested, 1-hydroxy-8alpha-estrone, 1-hydroxy-8alpha-estradiol and their acetates had a higher value of the dissociation index than that of estriol. These compounds seemed to exert a predominant effect on the vagina rather than on the uterus. Following structural factors seem to be of significance for the dissociation of estrogenic effects: the 1- or 16alpha- hydroxy group and 8alpha-configuration decrease the uterotrophic activity more intensely than the vaginotrophic activity, and the 17alpha-ethinyl group selectively increases the uterotrophic activity.