Isolation of new flavonol glycosides from the aerial parts of Lamium amplexicaule

Five flavonoid glycosides were isolated from the aerial parts of Lamium amplexicaule (Labiatae). The structures of the five isolated compounds were determined as luteolin 7-O-β-D-glucopyranoside (1), kaempferol 3-O-α-L-rhamnopyranosyl (1→6)-β-D-glucopyranoside (2), quercetin 3-O-α-L-rhamnopyranosyl (1→6)-β-D-glucopyranoside (3), kaempferol 3-O-[β-D-glucopyranosyl (1→4)][α-L-rhamnopyranosyl (1→6)]-β-D-glucopyranoside (4) and quercetin 3-O-[β-D-glucopyranosyl (1→4)][α-L-rhamnopyranosyl (1→6)]-β-D-glucopyranoside (5) on the basis of spectroscopic evidences. Compounds 4 and 5 were isolated for the first time from a natural source.