Chemical Investigation of the Constitutive Flavonoid Glycosides of the Leaves of Crataegus sinaica

Leaves of Crataegus sinaica Boiss, contain the new C-glycosyl flavone $3"',4”’-di-O-acetyl-2“-O-{\alpha}-rhamnosylvitexin$, together with the hitherto unknown, dihydroflavonol 3-O-xyloside, (2R:3R)-dihydroquercetin-$3-O-{\beta}-xylopyranoside$. The known compounds (+)-catechin, (-)-epicatechin, vicenin-II, $2"-O-{\alpha}-rhamnosylvitexin$, and $4"'-O-acetyl-2"-O-{\alpha}-rhamnosylvitexin$ were also characterized. Structures were established by conventional methods of analysis and confirmed by $^1H-,\;^{13}C-NMR$, and ESI-MS.