Estrogenic and antiestrogenic activity of novel selenosteroids.

An assay for estrogenic and antiestrogenic activity of seven selenoestrogens has been carried out in immature female rats. The estrogenic activity was compared to the in vitro binding affinity data. The study reveals that introduction of selenium substituents on C-16 or C-17 of the steroid nucleus produced a marked reduction in the estrogenic activity. The selenium analogues of ethynylestradiol produced the highest estrogenic activity. None of the compounds produced antiestrogenic activity.