Inhibition of nitric oxide production in lipopolysaccharide-stimulated RAW264.7 macrophage cells by lignans isolated from Euonymus alatus leaves and twigs.

The 80% methanolic extract of Euonymus alatus leaves and twigs afforded three new lignans, (-)-threo-4,9,4',9'-tetrahydroxy-3,7,3',5'-tetramethoxy-8-O-8'-neolignan (1), (-)-threo-4,9,4',9'-tetrahydroxy-3,5,7,3'-tetramethoxy-8-O-8'-neolignan (2), (7R,8R,7'R)-(+)-lyoniresinol (3), together with seventeen known lignans (4-20). The structures of 1-20 were elucidated by extensive 1D and 2D spectroscopic methods including (1)H NMR, (13)C NMR, (1)H-(1)H COSY, HMQC, HMBC and NOESY. All the isolated compounds except for dilignans (19 and 20) significantly inhibited nitric oxide production in lipopolysaccharide-stimulated RAW264.7 cells.