Limonoids from the Seeds of Swietenia macrophylla and Their Anti-Inflammatory Activities

A new limonoid, swietemacrophin (1), was isolated from the seeds of Swietenia macrophylla, together with five known compounds 2–6. The structure of 1 was determined through extensive 1D/2D-NMR and mass-spectrometric analyses. Swietemacrophin (1), humilinolide F (2), 3,6-O,O-diacetylswietenolide (3), 3-O-tigloylswietenolide (4), and swietemahonin E (5) exhibited inhibition (IC(50) values ≤ 45.44 μM) of superoxide anion generation by human neutrophils in response to formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP). Compounds 1, 4, 5, and swietenine (6) showed potent inhibition with IC(50) values ≤ 36.32 μM, against lipopolysaccharide (LPS)-induced nitric oxide (NO) generation.