Isolation and purification of antioxidative isomeric polyphenols from the roots of Parthenocissus laetevirens by counter-current chromatography.

Upright counter-current chromatography (CCC) with a two-phase solvent system composed of n-hexane-ethyl acetate-methanol-water (1:2:1:2, v/v/v/v) was applied to the isolation and purification of polyphenols from the roots of Parthenocissus laetevirens. Two cis-trans isomeric resveratrol dimers - quadrangularin A and parthenocissin A - were obtained from the crude sample in a one-step separation, with purities of 95.4 and 97.6%, respectively, as determined by HPLC. The structures of these two compounds were identified by (1)H NMR and (13)C NMR. Furthermore, their antioxidant activities were determined by beta-carotene bleaching assay. The antioxidant activities of quadrangularin A and parthenocissin A were higher than that of vitamin C in this model.