Polygala tenuifolia (Yuan Zhi) is an herb in the family Polygalaceae which is hardy to USDA Zone 6.Yuan Zhi is used primarily as an expectorant. It is one of the 50 fundamental herbs used in traditional Chinese medicine, where it is called yuan zhi.

Four xanthone O-glycosides, polygalaxanthones IV–VII were isolated from the roots of Polygalatenuifolia Willd., together with eight known compounds. The structures of the four xanthone O-glycosides were established as 6-O-[α-l-rhamnopyranosyl-(1→2)-β-d-glucopyranosyl]-1-hydroxy-3,7-dimethoxyxanthone (polygalaxanthone IV), 6-O-[α-l-rhamnopyranosyl-(1→2)-β-d-glucopyranosyl]-1,3-dihydroxy-7-methoxyxanthone (polygalaxanthone V), 6-O-(β-d-glucopyranosyl)-1,2,3,7-tetramethoxyxanthone (polygalaxanthone VI), and 3-O-[α-d-rhamnopyranosyl-(1→2)-β-d-glucopyranosyl]-1,6-dihydroxy-2,7-dimethoxyxanthone (polygalaxanthone VII), respectively, on the basis of analysis of spectroscopic evidence.