Anti-inflammatory effect of three iridoids in human neutrophils

To verify the anti-inflammatory potency of iridoids, three iridoids (two natural, loganic acid: LA; geniposide: GE; and an artefact, 7(S)-n-butyl morroniside: BM) were investigated in vitro on the inhibition of superoxide generation in human neutrophils. All compounds showed inhibitory effect on fMLP-induced superoxide generation in a concentration-dependent manner with the following order: BM>LA>GE. BM exhibits potent inhibitory activity on superoxide anion induced by PMA, while LA and GE showed weak effect. When AA was used as stimulus, the generation of superoxide anion was suppressed by BM in a concentration-dependent manner. LA and GE exhibit both sides effect on superoxide generation.