Selective 1O2 quenchers, oligostilbenes, from Vitis wilsonae: Structural identification and biogenetic relationship

Two previously unknown resveratrol trimers named wilsonols A-B, as well as a resveratrol tetramer named wilsonol C, were isolated from Vitis wilsonae Veitch, together with 12 known oligostilbenes. Their chemical structures have been elucidated by detailed analyses of ID and 2D NMR spectroscopic data, as well as chemical evidence obtained via either catalysis with HRP (horseradish peroxidase) and H2O2 (hydrogen peroxide), acid, or UV irradiation. During the chemical processes, a biomimetic resveratrol tetramer named diviniferin B that has not been found in nature was obtained. These oligostilbenes showed potent scavenging abilities towards DPPH radicals and selective quenching effects on O-1(2) radicals. Furthermore, the biogenetic transformations between the 16 oligostilbenes have been elaborated chemically to provide a comprehensive mechanism of the antioxidative defense system in this plant species. (C) 2012 Elsevier Ltd. All rights reserved.