New phenylethanoid glycosides from Veronica pectinata var. glandulosa and their free radical scavenging activities

Abstract

A known phenylethanoid glycoside, ehrenoside (1), was isolated together with three new phenylethanoid glycosides, verpectoside A (2), B (3) and C (4) from the aerial parts of Veronica pectinata var. glandulosa. On the basis of spectral analysis (UV, FAB-MS, 1H-, 13C- and 2D-NMR), compounds 2-4 were determined to be 2-(3,4-dihydroxyphenyl)ethyl-O-α-L- arabinopyranosyl-(1→2)-[α-L-rhamnopyranosyl-(1→3)] -(4-O-trans-feruloyl)-β-D-glucopyranoside, 2-(3,4-dihydroxyphenyl)ethyl-O- β-D-glucopyranosyl-(1→2)-[α-L-rhamnopyranosyl-(1→3)] -(4-O-trans-caffeoyl)-β-D-glucopyranoside and 2-(3,4-dihydroxyphenyl)ethyl- O-β-D-glucopyranosyl-(1→2)-[α-L-rhamnopyranosyl-(1→3)] -(4-O-trans-feruloyl)-β-D-glucopyranoside, respectively. Isolated phenylethanoid glycosides exhibited potent radical scavenging activity against the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical. © 2002 Pharmaceutical Society of Japan.