Saponin of Momordica cymbalaria Exhibits Anti-Inflammatory Activity by Suppressing the Expression of Inflammatory Mediators in Lipopolysaccharide-Stimulated RAW264.7 Macrophages

Background: Inflammation is an intricate biological process that commonly occurs in response to pathologic stimuli, and natural products have potential in healing inflammation. However, the anti-inflammatory of Momordica cymbalaria is not evaluated yet. Objectives: The anti-inflammatory mechanism of saponin of M. cymbalaria (SMC) was investigated in bacterial lipopolysaccharide (LPS)-stimulated RAW264.7 mouse macrophage cell line. Methods: The cytotoxicity of SMC on RAW264.7 cells was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay at 500, 250, 125, 62.5, 31.25, 15.625, 7.812, 3.906, and 1.953 mu g/mL. For anti-inflammatory activity, RAW264.7 cells were stimulated with Escherichia coli LPS (1 mu g/ml) in the presence or absence of SMC (50 mu g/ml) for 16-24 h. Western blotting was carried to comprehend the expression of cyclooxygenase-2 (COX-2) and inducible nitric oxide (NO) synthase (iNOS) whereas expressions of the pro-inflammatory cytokines (interleukin [IL]-6, IL-1 beta, and tumor necrosis factor-alpha [TNF-alpha]) and prostaglandin E-2 (PGE(2)) were studied by enzyme-linked immunosorbent assay (ELISA). NO production was estimated by Griess's method. Salicylic acid, a nonsteroidal anti-inflammatory drug, was used as a standard. Results: The saponin did not exert significant cytotoxicity on RAW264.7 cells. Western blot analysis revealed reduction in COX-2 and iNOS expression on SMC treatment. Production of PGE(2), IL-6, IL-1 beta, and TNF-alpha was also found to be reduced when analyzed by ELISA. NO levels were also lowered. Conclusions: The findings suggest that the SMC possesses potential anti-inflammatory activity by suppressing the expression of inflammatory mediators, COX-2, iNOS, PGE(2), and NO, and the cytokines in LPS-stimulated RAW264.7 cells.