Synthesis and estrogen receptor selectivity of 1,1-bis(4-hydroxyphenyl)-2-(p-halophenyl)ethylenes

A series of triarylethylenes (1a-e) were synthesized and evaluated for their ability to compete with [3H]estradiol for high-affinity estrogen receptors (ER) in immature rat uterine cytosol. All compounds showed affinity comparable to that of estradiol, with 1c having the highest affinity and the lowest calculated nonspecific binding of the para-halogenated members. Compound 1a had a higher affinity than did its chlorovinyl counterpart 1b, indicating that a vinyl hydrogen was suitable for high ER affinity in this series. Compound 1c was labeled with 3H ortho to one or both of its hydroxyls. Its ratio of specific to nonspecific binding in rat uterine cytosol, 3.2, was 140% of that of a related triarylethylene, 4-hydroxytamoxifen, and was 24% that of estradiol. Administration of [3H]-1c to immature female rats resulted in accumulation of 3H in uterine tissue which was decreased 39% when [3H]-1c was coadministered with estradiol. The major site of accumulation 1, 4, and 8 h after administration was in the intestinal tract. Chromatographic analysis showed that levels of 1c were less than those of 1c glucuronide in blood plasma, liver, and intestinal contents of rats 1 h after administration of 1c. Uterine 3H was comprised of 85% of 1c and 11% of 1c glucuronide. These results indicate that 1c undergoes ER-mediated uptake in the immature female rat, but selectivity is reduced due to nonspecific accumulation of free and conjugated 1c in uterine tissue.