The methanolic extract (200 mg/kg, p.o. and i.p.), principal coumarin constituents (isoepoxypteryxin, anomalin, and praeroside IV), and a polyacetylene constituent (falcarindiol) (25 mg/kg, i.p.) from the roots of Angelica furcijuga protected the liver injury induced by D-galactosamine (D-GalN)/lipopolysaccharide (LPS) in mice. In in vitro experiments, coumarin constituents (hyuganins A-D, anomalin, pteryxin, isopteryxin, and suksdorfin) and polyacetylene constituents [(-)-falcarinol and falcarindiol] substantially inhibited LPS-induced NO and/or TNF-alpha production in mouse peritoneal macrophages, and isoepoxypteryxin inhibited D-GalN-induced cytotoxicity in primary cultured rat hepatocytes. Furthermore, hyuganin A, anomalin, and isopteryxin inhibited the decrease in cell viability by TNF-alpha in L929 cells.