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.

Keywords::

• Uraria clarkei
• flavane
• cytotoxicity
• (2R)-4′-hydroxy-2′,5,7-trimethoxyflavan
• (2R,4R)-2′,4′-dihydroxy-5,7-dimethoxyflavan-4-ol

Acknowledgments

This work was financially supported by the National Natural Science Foundation of China (NSFC Nos 21162041, 21262047), the Science Foundation of the Education Department of Yunnan Province (2012J071), and the Independent Innovation Project for postgraduates (Nos 11HXYJS03, 2011HXDZB04) from the Key Laboratory of Chemistry in Ethnic Medicinal Resources, State Ethnic Affairs Commission and Ministry of Education, Yunnan University of Nationalities. We are grateful to Dr Chun-Suo Yao from the Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, for the registration of CD curve.