INHIBITION OF14C-ESTRONE METABOLISM IN RAT LIVER MICROSOMES BY 2-HYDROXYESTROGENS AND RELATED COMPOUNDS

Abstract

Inhibition studies with compounds having structural features in common with the natural estrogens have shown that 2-hydroxyestrone and 2-hydroxyestradiol are potent inhibitors of the rat liver microsomal system, which converts estrone to water-soluble protein-bound products. Simple phenols and naphthols hydroxylated in the ortho and para positions were also found to be good inhibitors, but the corresponding meta-hydroxylated compounds, as well as various anthraquinones and estrogens substituted in the 6, 10, or 16 positions, were inactive in this respect. The synthetic estrogen, hexestrol, lost its inhibitory activity on conversion to dihydroxyhexestrol, a nonestrogenic analogue. The type of inhibition produced by 2-hydroxyestrone, equilenin, diethylstilbestrol, and menadione was determined by the Lineweaver-Burk method and shown to be competitive for the first 3 of these compounds.