Adv Exp Med Biol. 2002 ; 505(): 151-61.

Human 17beta-hydroxysteroid dehydrogenase type 5 is inhibited by dietary flavonoids.

Krazeisen A, Breitling R, MÃ¶ller G, Adamski J.

GSF-National Research Center for Environment and Health, Institute for Experimental Genetics, Genome Analysis Center, Neuherberg, Germany.

Phytoestrogens contained in a vegetarian diet are supposed to have beneficial effects on the development and progression of a variety of endocrine-related cancers. We have tested the effect of a variety of dietary phytoestrogens, especially flavonoids, on the activity of human 17beta-hydroxysteroid dehydrogenase type 5 (17beta-HSD 5), a key enzyme in the metabolism of estrogens and androgens. Our studies show that reductive and oxidative activity of the enzyme are inhibited by many compounds, especially zearalenone, coumestrol, quercetin and biochanin A. Among flavones, inhibitor potency is enhanced with increased degree of hydroxylation. The most effective inhibitors seem to bind to the hydrophilic cofactor binding pocket of the enzyme.