Unusual phenolic glycosides from Cotoneaster orbicularis.

The whole plant of Cotoneaster orbicularis contains the novel di-C-glycosylflavone, 4",4"'-di-O-beta-glucopyranosyl-vicenin II, or 6,8-di-C-beta-Cellobiosylapigenin, as well as the hitherto unknown natural phenolic glucoside, gentisic acid 2-O-beta-glucopyranoside, or orbicularin. Further phenolics are protocatechuic, anisic, caffeic, p-coumaric acids, catechin, epicatechin, 2"-O-alpha-rhamnopyranosylvitexin, vitexin, rutin, isoquercetrin, hyperin and naringenin. All structures were determined by routine methods of analysis and confirmed mostly by 1H- and 13C-NMR.