Two new flavonol glycosides from Dimocarpus longan leaves

From the extracts of Dimocarpus longan Lour leaves, 2 unusual flavonol glycosides, quercetin 3-O-(3″-O-2‴-methyl-2‴-hydroxylethyl)-β-D-xyloside (1) and quercetin 3-O-(3″-O-2‴-methyl-2‴-hydroxylethyl)-α-L-rhamnopyranoside (2), as well as 10 known compounds including 2 flavonol glycosides, afzelin (3) and kaempferol-3-O-α-L-rhamnopyranoside (4), 2 flavans, (-)-epicatechin (5) and proanthocyanidin A-2 (6), 3 triterpenoids, friedelin (7), epifriedelanol (8) and β-amyrin (9), a peptide, N-benzoylphenylalanyl-N-benzoylphenylalaninate (10), and 2 sterols, β-sitosterol (11) and daucosterol (12) were isolated and identified by using combination of mass spectrometry and various 1D and 2D NMR techniques. This is the first report of flavonoid glycosides possessing a 2-methyl-2-hydroxylethoxyl group in sugar moiety from D. longan.