Biflavonoids from Daphne feddei and their inhibitory activities against nitric oxide production.

Bioassay-directed fractionation led to the isolation of two new biflavonoids and 13 known biflavonoids from a sample of the dried stem barks of Daphne feddei. The structures of compounds 1 and 2 were elucidated as 2''-methoxy-daphnodorin C (1) and 2''-methoxy-2-epi-daphnodorin C (2) on the basis of detailed spectroscopic analysis and X-ray crystallography. All 15 biflavonoids were tested for inhibitory activities against lipopolysaccharide (LPS)-induced nitric oxide (NO) production in RAW 264.7 macrophages. Compounds 1, 2, 8, 10, 14 and 15 showed varying degrees of inhibitory activities against the production of NO in tested concentration of 25, 50, 75 and 100 microg/ml.