Studies on Flavonoids from the Leaves of Engelhardia Roxburghiana

OBJECTIVE To study the flavonoids from the leaves of Engelhardia roxburghiana for better using the traditional Chinese medicine. METHODS The flavonoids was isolated and purified by silica gel, Sephadex LH-20 column chromatography, preparative HPLC and the structures were elucidated on the basis of spectral data including UV, HPLC/Q-TOF-ESI-MS, 1H-NMR, 13C-NMR, DEPT, HMBC and physiochemical properties. RESULTS Six flavonoids were obtained from the 95% ethanol extract and their structures were identified as astilbin (Ⅰ), engelitin (Ⅱ), quercitrin (Ⅲ), (2R, 3R)5,7,3’,4’-tetrahydroxyflavanonol-3-O-α-L-rhamnopyranosyl(3→1)-β-D-glucopyranoside (Ⅳ), (2R, 3R) 5, 7, 4'-trihydroxyfla- vanonol-3-O-α-L-rhamnopyranosyl (3→1)-β-D-glucopyranoside (Ⅴ), (2R, 3R)-5, 7, 4', 5'- tetrahydroxyflavanonol-3-O-(3"-O- galloyl)-α-L-rhamnopyranoside (Ⅵ), respectively. CONCLUSION Compound Ⅴ is first isolated from the title plant and reported for the first time.