Nonsteroidal estrogens and antiestrogens: biological activity of cyclopropyl analogs of stilbene and stilbenediol.

The estrogenic, antiestrogenic, and receptor binding activity of a series of cyclopropyl analogs of stilbene and stilbenediol were determined using the uterotropic assay in the mouse and the receptor binding assay with rat uterine cytosol. One compound, 1,1-dichloro-cis-2,3-diphenylcyclopropane (II), displayed antiestrogenic activity in vivo with a low affinity for the estrogen receptor in vitro and showed tumor remission activity on 7,12-dimethylbenz(a)anthracene-induced estrogen-dependent rat mammary tumors. Compounds VIII, IV, and V (in that order) exhibited the greatest estrogen activity in the mouse and the greatest receptor binding activity in vitro. Compound VIII exhibited antifertility activity in the mouse.