Catechol estrogens of the 1,1,2-triphenylbut-1-ene type: relationship between structure, estradiol receptor affinity, estrogenic and antiestrogenic properties, and mammary tumor inhibiting activities.

1,1,2-Triphenylbut-1-enes (26-35), which are substituted with one or two 3,4-diacetoxy groups or with one 3,4-diacetoxy and one 3- or 4-acetoxy group in two aromatic rings, were synthesized. The occurring E and Z isomers were isolated, and their identity was established by 1H NMR spectroscopy. A study on structure-activity relationship was carried out with regard to estradiol receptor affinity in vitro, estrogenic and antiestrogenic properties in the immature mouse, and inhibition of the hormone-dependent MXT mammary tumor of the mouse in vivo. Among the tested compounds, most of the 1,1-disubstituted 1,1,2-triphenylbut-1-enes (29, Z-30, Z,E-31) and (E)-1-(3-acetoxyphenyl)-1-phenyl-2-(3,4-diacetoxyphenyl)but- 1-ene (E-35) as well as its respective Z isomer (Z-35) exerted antiestrogenic properties. Compounds Z-30, Z,E-31, Z-35, and E-35 inhibited the growth of the hormone-dependent MXT tumor. The best antitumor effect without estrogenic side effects during therapy was shown by E-35.