Polysaccharide from Momordica Charantia Induces Immunostimulatory Responses and Reveals Mechanisms in Macrophages.

Background: Immunity protects organisms from pathogens, diseases, and external noxious agents. Naturally derived polysaccharides are well-documented to exhibit potent immunomodulatory effects. However, the exact immunostimulatory properties and underlying mechanisms of polysaccharides derived from Momordica charantia (MCPS) remain to be clearly elucidated. Objective: To investigate the immunomodulatory effects of MCPS on murine macrophages and to elucidate the underlying molecular mechanisms. Methods: MCPS was isolated from Momordica charantia. RAW 264.7 murine macrophages were treated with varying concentrations of MCPS, and its effects on cell viability, nitric oxide (NO) production, cytokine secretion, surface marker expression, and key intracellular signaling pathways were evaluated using standardized analytical assays. Potential endotoxin contamination was systematically excluded using a polymyxin B neutralization assay. Results: MCPS exhibited no cytotoxicity across all tested concentrations. Notably, MCPS significantly stimulated NO production and enhanced the secretion of pro-inflammatory cytokines, indicative of robust macrophage activation. This was accompanied by a marked upregulation of macrophage surface activation markers. Furthermore, MCPS activated the MAPK and NF-κB signaling pathways. This cytokine production was significantly attenuated by pathway-specific inhibitors, confirming the functional involvement of these cascades. Importantly, polymyxin B suppressed LPS-induced responses but did not alter MCPS- stimulated activation, indicating that the immunomodulatory effects were independent of endotoxin contamination. Conclusion: MCPS effectively promotes murine macrophage activation without cytotoxicity by stimulating NO production, cytokine secretion, and activation marker expression through the MAPK and NF-κB signaling pathways. These findings demonstrate that MCPS holds strong potential as a natural immunostimulatory agent capable of enhancing host immune responses.