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Targeted isolation and structure elucidation of stilbene glycosides from the bark of Lysidice brevicalyx Wei guided by biological and chemical screening.

An efficient procedure based on biological and chemical screening has been performed to investigate the antioxidant constituents of the bark of Lysidice brevicalyx Wei. The procedure allowed the rapid identification of known compounds and tentative characterization of unknown compounds by online LC/UV/ESIMS(n) analyses of the antioxidant fraction. Targeted isolation of the unknown compounds has led to the discovery of seven new stilbene glycosides, named lysidisides L-R (1-7), together with a known stilbene glycoside, (E)-resveratrol 3-O-rutinoside (8). The structures of these compounds were further determined on the basis of spectroscopic and chemical evidence. The antioxidant activities of compounds 1-8 and two related compounds, (E)-polydatin (9) and lysidiside E (11), were evaluated. The known compound (E)-polydatin (9) showed antioxidant activity at concentrations of 10(-4) and 10(-5) mol/L.