Xanthone O-glycosides from Polygala tenuifolia.

Four xanthone O-glycosides, polygalaxanthones IV-VII were isolated from the roots of Polygala tenuifolia Willd., together with eight known compounds. The structures of the four xanthone O-glycosides were established as 6-O-[alpha-L-rhamnopyranosyl-(1-->2)-beta-D-glucopyranosyl]-1-hydroxy-3,7-dimethoxyxanthone (polygalaxanthone IV), 6-O-[alpha-L-rhamnopyranosyl-(1-->2)-beta-D-glucopyranosyl]-1,3-dihydroxy-7-methoxyxanthone (polygalaxanthone V), 6-O-(beta-D-glucopyranosyl)-1,2,3,7-tetramethoxyxanthone (polygalaxanthone VI), and 3-O-[alpha-D-rhamnopyranosyl-(1-->2)-beta-D-glucopyranosyl]-1,6-dihydroxy-2,7-dimethoxyxanthone (polygalaxanthone VII), respectively, on the basis of analysis of spectroscopic evidence.