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 .