Effects of stilbene constituents from rhubarb on nitric oxide production in lipopolysaccharide-activated macrophages

Two new anthraquinone glucosides [chrysophanol 8-O-beta-D-(6'-galloyl)-gluc opyranoside, aloe-emodin 1-O-beta-D-glucopyranoside] together with various known stilbenes and their glucosides, anthraquinone glucosides, and a napht halene glucoside were isolated from the rhizome of Rheum undulatum L. Three stilbenes (rhapontigenin, piceatannol, resveratrol), a naphthalene glucosi de (torachrysone 8-O-beta-D-glucopyranoside), and two stilbene glucoside ga llates (rhaponticin 2 "-O-gallate, rhaponticin 6 "-O-gallate) showed inhibi tory activity of NO production in lipopolysaccharide-activated macrophages. (IC50 = 11-69 mu M). The oxygen Functions (-OH,-OCH3) at the benzene ring were found to be essential to show the activity. Whereas, the glucoside moi ety reduced the activity, while the alpha,beta-double bond did not affect t he activity. Furthermore; the active stilbenes (rhapontigenin, piceatannol, resveratrol) inhibited iNOS induction. (C) 2000 Elsevier Science Ltd. All rights reserved.