Study on Antioxidative Constituents in Rhizomes of Polygonum amplexicaule

OBJECTIVE To investigate the chemical constituents in rhizomes of Polygonum amplexicaule var.sinese.METHODS The compounds were isolated by chromatographic techniques with silica gel,Sephadex LH-20 and semi-preparative HPLC.Their structures were identified by analysis of physical and spectral evidence,and confirmed by comparison of their spectral data with reported values in the literature or those of authentic samples.The antioxidant activities of the compounds were evaluated by(ORAC) assay.RESULTS Twelve compounds were isolated and identified as daucosterol(1),quercetin-3-O-α-D-arabinopyranoside(2),catechin(3),gallic acid(4),5,7,2′,5′-tetrahydroxy-(2R,3R)-flavan-3-ol(5),phlorizin(6),protocatechuic acid methyl ester(7),methyl gallate(8),lyoniresinol(9),trans-ferulic acid(10),protocatechuic acid(11) and methyl chlorogenate(12),respectively.Compounds 2-7 and 9-12 had stronger antioxidant activities than vitamin C,and compound 8 showed weak activity.CONCLUSION All compounds were isolated from the species for the first time,and compounds 2-3,5 and 12 were obtained from this genus for the first time compounds 2-12 all showed potential antioxidant activities in ORAC assay.