2-Phenoxychromones and prenylflavonoids from Epimedium koreanum and their inhibitory effects on LPS-induced nitric oxide and interleukin-1β production.

Two new 2-phenoxychromones 1 and 2 and two prenylflavonoids 3 and 4 along with 12 known compounds (5-16) were isolated from the CH2Cl2-soluble fraction of a methanol extract of Epimedium koreanum. Compounds 1, 4, 6, 7, 9, 10, 12, and 15 exhibit inhibitory effects on nitric oxide production with IC50 values ranging from 16.8 to 49.3 μM. Compounds 1, 4, 7, and 12 also showed inhibitory effects on interleukin-1β production with IC50 values ranging from 8.6 to 38.9 μM in RAW 264.7 macrophages.