Abstract
Acute inflammation is frequently triggered by pathogen infections and contributes to host mortality. In this study, a new exopolysaccharide (ObEPS) was isolated from the moss endophyte Ovatospora brasiliensis and characterized for its structure and biological activity. Monosaccharide composition analysis revealed that ObEPS was mainly composed of galactose, glucose, mannose, and glucuronic acid. Multi-angle light scattering and conformation analysis showed a molar mass of 105-106 Da and a compact chain conformation. In vitro experiments showed that ObEPS markedly inhibited nitric oxide production and reduced pro-inflammatory cytokine expression in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. In a systemic Candida albicans infection model, ObEPS combined with fluconazole significantly reduced fungal colony-forming units (CFUs)/g kidney from 3.8 × 105 to 0.1 × 105, with the reduction of pro-inflammatory cytokine levels and tissue damage compared with the EPS-free groups suffering from C. albicans infection. Overall, these findings indicate that ObEPS has potent anti-inflammatory activity and may serve as a promising natural adjunct for mitigating infection-associated inflammatory damage.