BG-4, a novel bioactive peptide from momordica charantia, inhibits lipopolysaccharide-induced inflammation in THP-1 human macrophages

Background: Bitter melon (Momordica charantia) is a commonly used food crop for management of a variety of diseases most notably for control of diabetes, a disease associated with aberrant inflammation. Purpose: To evaluate the anti-inflammatory property of BG-4, a novel bioactive peptide isolated from the seed of bitter melon. Methods: Differentiated THP-1 human macrophages were pre-treated with BG-4 and stimulated with lipopolysaccharide. Pro-inflammatory cytokines IL-6 and TNF-alpha were measured by enzyme-linked immunosorbent assay. The mechanism of action involving activation of NF-kappa B and phosphorylation of ERK and STAT3 was measured by western blot and immunofluorescence. The production of intracellular reactive oxygen species was evaluated by fluorescence microscopy and fluorescence spectrophotometry. Results: BG-4 dose dependently reduce the production of pro-inflammatory cytokines IL-6 and TNF-alpha. The ability of BG-4 to reduce production of cytokines are associated with reduced phosphorylation of ERK and STAT3 accompanied by reduced nuclear translocation of p65 NF-kappa B subunit. The mechanism of action is reduction of LPS-induced production of intracellular reactive oxygen species. Conclusion: Our results demonstrated the ability of BG-4, a novel peptide from the seed of bitter melon, to exert anti-inflammatory action. This could explain the traditional use of bitter melon against diseases associated with aberrant and uncontrolled inflammation.