Anti-Inflammatory Effects of Canavalia gladiata in Macrophage Cells and DSS-Induced Colitis Mouse Model

Abstract

Canavalia gladiata, known as sword bean, has been used as a Chinese traditional medicine for anti-inflammatory effects. However, the action mechanisms of sword bean have not yet been clearly defined. In the present study, the whole parts of a ripened sword bean (RSB) and the green sword bean (GSB) containing bean pod were extracted with ethanol by reflux extraction. The two crude extracts (RSBE and GSBE) from RSB and GSB were validated by a liquid chromatography-tandem mass spectrometry (LC/MS/MS) analysis of gallic acid as a reference chemical. The anti-inflammatory effects of two sword bean extracts were extensively investigated using LPS-stimulated macrophage cells. First, RSBE and GSBE significantly inhibited the production of pro-inflammatory mediators, such as tumor necrosis factor-$\alpha$ (TNF-$\alpha$), interleukin-6 (IL-6), prostaglandinE₂ (PGE₂), and nitric oxide (NO) in LPS-induced RAW264.7 cells. RSBE and GSBE showed no cytotoxicity to RAW264.7 cells and mouse peritoneal macrophage cells. In addition, the overexpression of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) induced by LPS in RAW264.7 cells was significantly decreased by RSBE and GSBE. Western blotting and immunostaining analysis showed that RSBE and GSBE inhibited the nuclear translocation of NF-$\kappa$B subunits, which correlated with the inhibitory effects on inhibitor kappa B (I$\kappa$B) degradation. In dextran sulfated sodium (DSS)-induced colitis mice model, RSBE restored body weight, colon length, and the levels of pro-inflammatory cytokines, such as TNF-$\alpha$, IL-6, interleukin-1$\beta$ (IL-1$\beta$), and interferon-$\gamma$ (IFN-$\gamma$). In addition, RSBE significantly suppressed the expression of COX-2, iNOS, and NF-$\kappa$B.

Keywords: Cox-2; DSS-Induced Colitis Mouse Model; Inflammation; MAPKs; NF-κB; Sword Bean; iNOS.