Estrogenic and antiestrogenic activities of two new nonsteroidal antifertility agents

Compounds E696 and E785 (Alkanoic acid derivatives) prevented pregnancy in rats following a single oral administration on day 1 post coitum. Both the compounds were found to possess potent estrogenic activity as revealed by increased uterine weight, premature opening of vagina and cornification of the vaginal epithelium in immature rats. In adult rats, the two compounds induced implantation of delayed blastocysts. Mild estrogenic response was discerned even 21 days after a single oral administration of each of these compounds to immature animals. However, neither of these compounds exhibited any estrogen antagonistic or synergistic property. The contraceptive and estrogenic activities of these compounds have been compared to ethinyl estradiol.