Anti-Inflammatory Potential of Extracellular Polysaccharide from the Moss Endophyte Ovatospora brasiliensis During Pathogen Infection

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 <i>Ovatospora brasiliensis</i> 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 <i>Candida albicans</i> 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 <i>C. albicans</i> 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.