Structure-activity relationship of estrogens: receptor affinity and estrogen antagonist activity of certain (E)- and (Z)-1,2,3-triaryl-2-propen-1-ones

(E)- and (Z)-1,2,3-triphenyl-2-propen-1-ones and some of their phenolic and alkoxy analogues, substituted at the para position in one or more of the aromatic rings, were synthesized and assigned geometry on the basis of their spectroscopic data. The structure-activity relationship of the triarylpropenones was studied from the point of view of their estrogen receptor affinity and estrogen agonist and antagonist activities. (E)- as well as (Z)-propenones were found to compete with estradiol for binding with the mouse uterine cytosol receptors, with phenolic analogues usually more potent than the unsubstituted as well as alkoxypropenones. The (E)-propenones, which have now emerged as a new group of estrogen receptor ligands, were found to differ from Z isomers quite markedly in their binding specificities. The uterotrophic and antiuterotrophic assays in immature mice revealed that while some of the compounds were marginally estrogenic, nearly all the isomeric propenones were antiestrogenic to a varying degree.