A new flavonoid glycoside from the leaf of Cephalotaxus koreana

A new flavone glycoside, apigenin 5-O-α−l-rhamnopyranosyl-(1 → 3)-β-d-glucopyranoside (1), along with four known flavonol glycosides (2-5), were isolated from the leaf of Cephalotaxus koreana. The new glycoside 1 showed inhibitory activity in superoxide radical scavenging assay with IC50 value of 13.0 μM, while it showed weak activity in 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging assay. Compounds 2−5 exhibited antioxidant activity in scavenging DPPH and superoxide radicals with IC50 values ranging from 5.7 to 22.3 μM.