[Potential antiestrogens of the 1,2-diphenyl-1-pyridyl-but-1-ene type. 2. Biological testing].

Z-1-(4-hydroxyphenyl)-1-(4-resp. 3-pyridyl)-2-phenyl-but-1-enes Z-1 and Z-2 and their acetates Z-1a and Z-2a are weak estrogens (uterine weight test, immature mouse), which cause a marked tumor growth inhibition on the hormone-dependent MXT mammary carcinoma of the mouse. No or just slight estrogenic side effects determined by uterine weight are detectable in this tumor experiment.