Antioxidant flavonoids from Epimedium wushanense.

Two new flavonoids, wushanicaritin (1) and wushankaempferol (2), along with 24 known flavonoids were isolated from the whole herb of Epimedium wushanense T.S. Ying (Berberidaceae). On the basis of NMR and ESI-MS spectroscopic analysis, structures of compounds 1 and 2 were elucidated as 8-γ-hydroxy-γ,γ-dimethylpropyl-3,5,7-trihydroxy-4'- methoxyflavone and kaempferol 3-O-α-l-[2,3-di-O-β-D-(6-E-p-coumaroyl) glucopyranosyl]-rhamnopyranosyl-7-O-α-L-rhamnopyranoside, respectively. DPPH radical scavenging activity tests indicated that 1 (IC(50) 35.3 μM) exhibited antioxidant activity comparable to Vitamin C (IC(50) 32.0 μM), while 2 (IC(50) 443.7 μM) showed weak activity.