Three new compounds from Anoectochilus roxburghii (Wall.) Lindl

In this study, three new compounds, roxburic acid A (1) and two flavone glycosides isorhamnetin-3-O-alpha-L-rhamnosyl-(1 -> 6)-beta-D-glucopyranose-(1 -> 3)-beta-D-glucopyranoside (2), and kaempferol-7-O-beta-D-glucopyranosyl-(1 -> 3)-beta-D-glucopyranoside (3) were isolated from an ethanol extract of the fresh Anoectochilus roxburghii (Wall.) Lindl., together with 10 known compounds (4-13). The structures of these compounds were comprehensively characterized by HR-ESI-MS, H-1 NMR, C-13 NMR, and 2 D-NMR. The DPPH free radical scavenging activity of the isolated compounds was evaluated, and the results showed that kaempferol-7-O-beta-D-glucopyranosyl- (1 -> 3) -beta-D-glucopyranoside (3) and rutin (11) has the potential antioxidant activity with IC50 values of 139 mu g/mL and 22.5 mu g/mL respectively.