Saussurea lappa Clarke extract exhibits potent antioxidant effect and attenuates neuroinflammatory responses in lipopolysaccharide-stimulated microglial cells

Purpose: To investigate the antioxidant and anti-neuroinflammatory potential of Saussurea lappa Clarke (SLC-EA) extract in LPS-stimulated BV-2 microglial cells.Methods: Cell viability was measured by using the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay while antioxidant activity was evaluated by using the DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging activity. Lipopolysaccharide (LPS) was used to stimulate BV-2 microglia. Griess assay was employed to assess nitric oxide (NO) production. iNOS (inducible NO synthase) expression and TNF-α (tumor necrosis factor-alpha) cytokine production were measured by ELISA (enzyme-linked immunosorbent assay) and immuno blot analysis, respectively.Results: Pretreatment of 100 mg/ml of SLC-EA (p < 0.001) was inhibited Nitric Oxide (NO) by 1 ug/ml of LPS-treated murine BV-2 cells. The expression of iNOS and TNF-α were reduced by SLC-EA concentration dependent manner (p < 0.001 at 100 mg/ml). SLC-EA were scavenged 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radicals in a dose-dependent manner with an IC50 value of approximately 51.4 μg/ml.Conclusion: The results indicate that SLC-EA extract exhibits strong antioxidant properties and inhibits excessive pro-inflammatory cytokine due probably to the antioxidant phenolic compounds present in SLC-EA extract. Further work in exploring the in-depth mechanisms of SLC-EA extract in regulating inflammatory signaling pathways in treating neuroinflammatory diseases is necessary. Keywords: Saussurea lappa, Antioxidant, Neuroinflammation, Microglia, TNF-α, iNOS