RELATIVE POTENCY OF CERTAIN SYNTHETIC ESTROGENS WHEN ADMINISTERED ORALLY TO CHICKS

Abstract

The relative estrogenic potency of certain synthetic estrogens was detd. on the basis of oviduct stimulation in young White Leghorn chicks. In 2 of the 3 tests conducted, 4 estrogens were fed at 3 levels: 10, 20, and 30 mg./lb. of feed. In each of these 2 tests there were 13 (duplicate) treatment groups involving 199 and 241 chicks. In the 3d test, 2 new estrogens plus the most and the least potent compounds, as detd. in the first 2 tests, were fed at the 30 mg. level. There were 5 (duplicate) treatment groups involving 146 chicks. The tests were terminated on 14th day. The descending order of potency of the 6 estrogens within the dose range employed is as follows: Dianisylhexane (dimethyl ether of hexestrol), dianisylhexene (dimethyl ether of diethylstilbestrol), hexestrol, dienestrol, dianisylhexadiene (dimethyl ether of dienestrol), diethylstilbestrol. There is some evidence that at dose levels above 30 mg., dianisylhexene may prove more potent than dianisylhexane. The estrogenic potency of these 6 compounds varies with the degree of saturation in the aliphatic block of the molecule and the nature of side chains attached to 4-4[image]- and [alpha, [beta]-positions, increasing saturation and methylation favoring increased estrogenicity. The degree of variability in oviduct response rises with the increased dose level of estrogens.