Isolation of Flavonoids from Populus nigra as Δ4-3-Ketosteroid (5α) Reductase Inhibitors

Abstract

Inhibitors of Δ4-3-ketosteroid (5α) reductase, which had been prepared from rat prostate and converted testosterone to 5a-dihydrotestosterone and 4-androstene-3,17-dione, were isolated from 50% ethanol extract of Populus nigra. They were identified as pinobanksin (I, 3,5,7-trihydroxyflavanone), 3,7-dimethylquercetin (II, 3‘,4’,5-trihydroxy-3,7-dimethoxyflavone) and pinocembrin (III, 5,7-dihydroxyflavanone). Compound III showed the most potent inhibitory activity among them. © 1989, The Pharmaceutical Society of Japan. All rights reserved.