A novel flavonoid glucloside from Anoectochilus roxburghii (Wall.) Lindl.

Eight compounds were isolated from the ethyl acetate- and n-butanol-soluble fractions of the ethanolic extract of the whole plant of Anoectochilus roxburghii (Wall.) Lindl. (Orchidaceae). On the basis of spectroscopic methods, the structures of these compounds were elucidated as quercetin-7-O-beta-D-[6"-O-(trans-feruloyl)]-glucopyranoside (compound 1), 8-C-p-Hydroxybenzylquercetin (compound 2), isorhamnetin-7-O-beta-D-glucopyranoside (compound 3), isorhamnetin-3-O-beta-D-glucopyranoside (compound 4), kaempferol-3-O-beta-D-glucopyranoside (compound 5), kaempferol-7-O-beta-D-glucopyranoside (compound 6), 5-hydroxy-3',4',7-trimethoxyflavonol-3-O-beta-D-rutinoside (compound 7), and isorhamnetin-3-O-beta-D-rutinoside (compound 8). Of the compounds isolated, compound 1 was a new flavonoid glucoside and exhibited strong scavenging activity against the 1,1-diphenyl-2-picrylhydrazyl free radical, whereas the ethanolic extract showed weak activity. Compounds 2-8 were obtained from this family for the first time.