Identification and characterization of three new flavonoids from Rhododendron dauricum.

The present study was designed to determine the major chemical constituents of the leaves of Rhododendron dauricum L. Compounds were isolated and purified by various chromatographic methods, and their structures were elucidated by physicochemical properties and spectral data. The present study identified two new C-methyl flavanones, 5, 7, 3', 5'-tetrahydroxy-6, 8-di-C-methyl flavanone (1) and 5, 4'-dihydroxy-8-C-methylflavanone-7-O-β-D-glucopyranoside (2), and one new flavonoid glycoside, quercetin-3-O-β-D-(6"-O-cinnamoyl)-galactoside (3), along with seven known compounds, including syzalterin (4), poriolin (5), farrerol-7-O-β-D-glucopyranoside (6), myrciacetin (7), quercetin-3-O-β-D-(6-p-hydroxy-benzoyl)-galactoside (8), quercetin-3-O-β-D-(6-p-coumaroyl)-galactoside (9), and 5, 7, 3', 5'-tetrahydroxyl flavanone (10). Compounds 1-3 were determined to be new flavonoids; compounds 4-6 were isolated from this species for the first time; and compounds 7-10 were reported for the first time from this genus.