Inducible nitric oxide synthase inhibitors fromMelia azedarach var.Japonica

In bioassay-guided search for inducible nitric oxide synthase (iNOS) inhibitory compounds from higher plants of South Korea, two β-carboline alkaloids, 4-methoxy-1-vinyl-β-carboline (1) and 4,8-dimethoxy-1-vinyl-β-carboline (2) have been isolated from the cortex ofMelia azedarach var.japonica. The structures of these compounds were elucidated on the basis of spectroscopic data. Compounds1 and2 showed marked inhibitory activity of iNOS on LPS-and interferon-γ-stimulated RAW 264.7 cells.