Anticomplementary activity of stilbenes from medicinal plants

The anticomplementary activity of stilbenes from medicinal plants in Korea was investigatedin vitro. 3,5-Dihydroxy-4′-methoxystilbene (3) was most potent with IC₅₀ value of 1.5×10⁻⁴ M followed by rhapontigenin (4), oxyresverastrol (2), 2,3,4′,5-tetrahydroxystilbene-2-O-β-glucoside (9), rhaponticin (8), resverastrol (1), and piceid (7). The activity was found to be increased by a methylation on a hydroxy group of C-4′ of1, but decreased by further methylation on hydroxy groups of C-3 and C-5 and glucosylation on any hydroxy group of1. Addition of hydroxy group on C-2′ of1 or C-3′ of3 was little affected on the anticomplementary activity but the activity was increased byO-glucosylation on C-2 of1.