Synthesis and study of the contraceptive activity of 8-isoestradiol analogues

Contraceptive preparations containing estrogens have a number of side effects caused primarily by the effect of the estrogen component. A search is underway in Russia for modified estrogens with sufficiently high contraceptive activity with a reduced hormonal (uterotropic) effect. In 1981 peculiarities of combining 8-isoanalogue estrogen steroids with cytoplasmic receptors of a rat uterus were detected making it possible to predict precisely what kind of micromodifications in the structure of 8-isoestradiol would result in a marked reduction in uterotropic activity. Experiments were conducted on female rats rabbits and mice. A physiological solution was injected in animals in the control group. Compound II was studied in rats in doses of 0.001 and 0.005 mg/kg; the contraceptive effect in a dose of 0.001 mg/kg was 6 (P