In bioassay-guided search for inducible nitric oxide synthase (iNOS) inhibi
tory compounds from higher plants of South Korea, two beta-carboline alkalo
ids, 4-methoxy-1-vinyl-beta-carboline (1) and 4,8-dimethoxy-1-vinyl-beta-ca
rboline (2) have been isolated from the cortex of Melia azedarach var. japo
nica. The structures of these compounds were elucidated on the basis of spe
ctroscopic data. Compounds 1 and 2 showed marked inhibitory activity of iNO
S on LPS- and interferon-gamma-stimulated RAW 264.7 cells.