Hexaoxygenated Flavonoids from Pteroxygonum giraldii

Abstract

Two flavonoids with an unusual 2′,4′,5′-trisubstituted B-ring (1 and 2), four myricetin derivatives (3-methylmyricetin-3′-O-β-D-xylopyranoside (3), myricetin-3-O-α-L-rhamnopyranoside, myricetin-3-O-β-D-galactopyranoside, and 3-methylmyricetin), and myricetin were isolated from the roots of Pteroxygonum giraldii Damm. & Diels. Their structures were elucidated using various spectroscopic methods and acid hydrolysis. Compound 1 was a new flavonoid and the NMR spectroscopic data of compounds 2 and 3 are reported for the first time.