Acylated flavonol glycosides with anti-complement activity from Persicaria lapathifolia

Abstract

During a search for biologically active compounds from traditional medicines, a crude extract of Persicaria lapathifolia was found to have anti- complement activity. Bioassay-guided chromatographic separation of the active constituents led to the isolation of a new acylated kaempferol glycoside (1) and three known acylated quercetin glycosides (2 - 4). The structures of compounds 1 - 4 were characterized as kaempferol 3-O-β-D-(6'-p- hydroxybenzoyl)-galactopyranoside, quercetin 3-O-β-D-(6'-feruloyl)- galactopyranoside, quercetin 3-O-β-D-(2'-galloyl)-rhamnopyranoside and quercetin 3-O-β-D-(2'-galloyl)-glucopyranoside, respectively. Compounds 1 - 4 showed strong anti-complement activity (IC50 values of 4.3, 9.7, 3.9 and 7.6 x 10-5 M, respectively) on the classical pathway of the complement. On the other hand, six isolated flavonol glycosides (510) did not show any activity on this system.