Antioxidant flavonoids and isoflavonoids from rhizomes of Iris pseudopumila.

Chromatographic separation of a methanolic extract from Iris pseudopumila rhizomes led to the isolation of two new natural compounds, irilone 4'-O-[beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranoside] and isoscutellarein 6-C-beta-D-glucopyranoside, along with 9 isoflavonoids and 4 flavonoids. Their structures were determined on the basis of spectroscopic evidence. Isolated compounds were evaluated for their antioxidant activity using the luminol-dependent chemiluminescence assay, with quercetin as a positive control. Irilone 4'-O-beta-D-glucopyranoside and kaempferol 3-O-[alpha-L-rhamnopyranosyl-(1-->6)-beta-D-glucopyranoside] showed significant antioxidant activity.