The Anti-inflammatory Mechanism of the Peel of Zanthoxylum piperitum D.C. is by Suppressing NF-κB/Caspase-1 Activation in LPS-Induced RAW264.7 Cells

Zanthoxylum piperitum D.C. (ZP) peels has been used as a natural spice and herb medicine for hypertension reduction, for strokes, and for its anti-bacterial and anti-oxidant activity. However, the anti-inflammatory mechanisms employed by ZP have yet to be completely understood. In this study, we elucidate the anti-inflammatory mechanism of ZP in lipopolysaccharide (LPS)-induced RAW264.7 cells. We evaluated the effects of ZP in LPS-induced levels of inflammatory cytokines, prostaglandin E₂ (PGE₂), and caspase-1 using ELISA. The expression levels of inflammatory-related genes, including cyclooxygenase (COX)-2 and inducible nitric oxide synthase (iNOS), were assayed by Western blot analysis. We elucidated the effect of ZP on nuclear factor (NF)-κB activation by means of a luciferase activity assay. The findings of this study demonstrated that ZP inhibited the production of inflammatory cytokine and PGE₂ and inhibited the increased levels of COX-2 and iNOS caused by LPS. Additionally, we showed that the anti-inflammatory effect of ZP arises by suppressing the activation of NF-κB and caspase-1 in LPS- induced RAW264.7 cells. These results provide novel insights into the pharmacological actions of ZP as a potential candidate for development of new drugs to treat inflammatory diseases.