Structure-activity relationships of 9β-estrogens

Article abstract of DOI:10.1016/0039-128X(83)90119-8

The 9β isomers of estradiol-17β, estradiol-17α, estrone and 17-ethinylestradiol-17β were synthesized and compared with their 9α-counterparts in the rat uterine cytosol estrogen receptor, uterotropic, and gonadotropin release inhibition assays. Except for 17-ethinyl-9β-estradiol-17β which was as active as its 9α isomer in the uterotropic assay, none of the 9β estrogens exhibited any biological activity which was equal to or greater than their 9α counterparts. For examples, 9β-estradiol-17β was 1/10 as active as estradiol-17β, and 9β-estrone was 1/4 as active as estrone in the uterotropic assay.