Two New Flavonol Glycosides from Polygala sibirica L. var megalopha Fr.

Two new flavonol glycosides, named polygalin H (1) and polygalin I (2), as well as the known compound polygalin D (3), were isolated from the whole plant of Polygala sibirica L. var megalopha Fr. Their structures were elucidated on the basis of spectroscopic data analysis. These flavonol glycosides exhibited strong inhibitory activities against xanthine oxidase in vitro. Their half-maximal inhibitory concentrations (IC50) were calculated, which were 9.48, 8.31, 16.00 M, respectively.