Abstract: Stilbene glycosides were isolated from the EtOH extract of the roots of Polygonum multiglorum Thunb. Three fractions were obtained: the crude EtOH extract, the fraction by macroporous resin and the purity crystal stilbene. The structures of crystal were determined by HPLC-MS, NMR and X- diffraction analysis. The antioxidant activities of three fraction of stilbene isolated were evaluated with different antioxidant tests, including reducing power, the lipid peroxides inhibition, free radical scavenging, superoxide anion radical scavenging and hydroxyl radical scavenging respectively in vitro. These various antioxidant activities were compared with resveratrol. The results indicated that the antioxidant activities of the three fractions are very good, and crystal stilbene is even more efficient: DPPH IC50 8.06μg/ml; hydroxyl radical scavenging IC50 2.75μg/ml and superoxide anion radical scavenging IC50 0.57μg/ml. All are belter than resveratrol.

Key words: Polygonum multiglorum Thunb, stilbene glycosides, antioxidant activity, free radical scavenging