Anti-inflammatory effect of neo-lignan isoamericanin A via suppression of NF-kappa B in liposaccharide-stimulated RAW 264.7 cells

Abstract

Purpose: To investigate the potential anti-inflammatory effects of the seeds of Opuntina humifusa and its active constituents. Methods: The extract of O. humifusa seeds was tested for the inhibition of nitric oxide (NO) production in liposaccharide (LPS)-stimulated RAW 264.7 cells using Griess reagent. The active constituents were isolated using bioassay-guided isolation methods. The effects of the active constituent on NO, proinflammatory cytokines, nuclear factor-kappa B (NF-kappa B) and nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor (I kappa B) were evaluated by enzyme-linked immunosorbent assay (ELISA) and western blot analysis. Results: The seed extract of O. humifusa significantly attenuated LPS-induced NO production in RAW 264.7 cells (p < 0.05). Bioassay-guided fractionation resulted in the isolation of isoamericanin A as an active constituent. Isoamericanin A reduced LPS-induced production of NO, iNOS, and proinflammatory cytokines (TNF-alpha and IL-6) in a concentration-dependent manner (p < 0.05). Furthermore, the effect was accompanied by decreased translocation of NF-kappa B from the cytosol to the nucleus and the decreased phosphorylation of I kappa B in the cytosol induced by LPS (p < 0.05). Conclusion: The seed extract of O. humifusa and its active constituent, isoamericanin A, have antiinflammatory effects in LPS-stimulated RAW 264.7 cells, suggesting that they have potentials as antiinflammatory agents.