Cytotoxic flavanes from Uraria clarkei

Abstract

Two new flavanes, (2R)-4′-hydroxy-2′,5,7-trimethoxyflavane (1) and (2R,4R)-2′,4′-dihydroxy-5,7-dimethoxyflavan-4-ol (2), were isolated from Uraria clarkei, together with two known compounds 5,7-dimethoxy-4′-hydroxyflavan (3) and 5,7,4′-trimethoxyflavan (4). The structures of the new flavanes were characterized by analyses of the MS, IR, UV, CD, 1D, and 2D NMR data. Cytotoxicity test suggested that compounds 1–4 possessed slight activity against K-562 and Hela cell lines, with the IC50 values ranging from 26.6 to 56.3 μM.