A new flavonol derivative from Fagopyrum dibotrys

A new flavonol derivative 3, 8-dihydroxy-10-methoxy-5-H-isochromeno[4, 3-b]chromen-7-one (1) together with four known compounds, glutinone (2), luteolin (3), acacetin 7-O-alpha-L-rhamnopyranosyl- (1 -> 6)-beta-D-glucopyranoside (4), and rutin (5) were isolated from the dried roots of Fagopyrum dibotrys. Their structures were determined by UV, IR, MS, H-1, and C-13 NMR spectroscopic analysis, including 2D NMR.