Five New Phenylethanoid Glycosides from the Whole Plants of Lamium purpureum L.

Abstract

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-β-D-galactopyranosyl-(1→2)-α-L-rhamnopyranosyl-(1→3)-(4-O-trans-caffeoyl)-β-D-glucopyranoside (1), 2-(3,4-dihydroxyphenyl)ethyl-O-β-D-galactopyranosyl-(1→2)-α-L-rhamnopyranosyl-(1→3)-(4-O-trans-feruloyl)-β-D-glucopyranoside (2), 2-(3,4-dihydroxyphenyl)ethyl-O-β-D-galactopyranosyl-(1→2)-α-L-rhamnopyranosyl-(1→3)-(6-O-trans-caffeoyl)-β-D-glucopyranoside (3), 2-(3,4-dihydroxyphenyl)-R,S-methoxy-ethyl-O-β-D-galactopyranosyl-(1→2)-α-L-rhamnopyranosyl-(1→3)-(4-O-trans-caffeoyl)-β-D-glucopyranoside (4) and 2-(3-hydroxy-4-methoxyphenyl)ethyl-O-α-L-rhamnopyranosyl-(1→3)-β-D-glucopyranosyl-(1→6)-(4-O-cis-feruloyl)-β-D-glucopyranoside (5). In addition, the radical-scavenging activities of compounds 1—4 on 1,1-diphenyl-2-picrylhydrazyl radical were examined.