Five new phenylethanoid glycosides from the whole plants of Lamium purpureum L.

Five new phenylethanoid glycosides, lamiusides A (1), B (2), C (3), D (4) and E (5), were isolated from the whole plants of Lamium purpureum L. (Labiatae) together with seven known compounds (6-12). On the basis of chemical and spectral analyses, the structures of the new compounds were elucidated to be 2-(3,4-dihydroxyphenyl)ethyl-O-beta-D-galactopyranosyl-(1-->2)-alpha-L-rhamnopyranosyl-(1-->3)-(4-O-trans-caffeoyl)-beta-D-glucopyranoside (1), 2-(3,4-dihydroxyphenyl)ethyl-O-beta-D-galactopyranosyl-(1-->2)-alpha-L-rhamnopyranosyl-(1-->3)-(4-O-trans-feruloyl)-beta-D-glucopyranoside (2), 2-(3,4-dihydroxyphenyl)ethyl-O-beta-D-galactopyranosyl-(1-->2)-alpha-L-rhamnopyranosyl-(1-->3)-(6-O-trans-caffeoyl)-beta-D-glucopyranoside (3), 2-(3,4-dihydroxyphenyl)-R,S-methoxy-ethyl-O-beta-D-galactopyranosyl-(1-->2)-alpha-L-rhamnopyranosyl-(1-->3)-(4-O-trans-caffeoyl)-beta-D-glucopyranoside (4) and 2-(3-hydroxy-4-methoxyphenyl)ethyl-O-alpha-L-rhamnopyranosyl-(1-->3)-beta-D-glucopyranosyl-(1-->6)-(4-O-cis-feruloyl)-beta-D-glucopyranoside (5). In addition, the radical-scavenging activities of compounds 1-4 on 1,1-diphenyl-2-picrylhydrazyl radical were examined.