Structure characterization and in vitro immunomodulatory effects of a novel galactoglucomannan in cultivated Chinese cordyceps (Cordyceps sinensis).

Chinese cordyceps (Cordyceps sinensis) is a rare medicinal fungus with significant therapeutic value, and its cultivated variants have garnered increasing attention in recent years. However, detailed structural and functional insights into cultivated Chinese cordyceps (CCC) polysaccharides remain limited. In this study, a novel galactoglucomannan (CSWP-80) with a molecular weight (Mw) of 26.2 kDa was extracted and purified from CCC. Structure characterization revealed that CSWP-80 possessed a backbone composed of →2)-α-D-Manp-(1 → and →6)-α-D-Glcp-(1→, substituted at the C-3 position by side chains containing Galf, Manp, and minor Glcp residues. The Galf side chains are predominantly composed of →5)-β-D-Galf-(1→, →6)-β-D-Galf-(1→, and terminal β-D-Galf-(1 → units. The Manp and Glcp side chains primarily consists of →4)-β-D-Manp-(1→, →2)-α-D-Manp-(1→, →4)-α-D-Glcp-(1 → linkages, along with terminal α-D-Manp-(1→ units. Tripartite antioxidant assessment systems (DPPH, SOD, FRAP) demonstrated that CSWP-80 possessed excellent antioxidant capacity. Furthermore, immune tests revealed that CSWP-80 not only enhanced macrophage proliferation and phagocytic activities but also stimulated the secretion of nitric oxide and cytokines (e.g., TNF-α, IL-10 and IL-6), indicating superior immunomodulatory properties. Mechanistic studies suggested that CSWP-80 likely activated macrophages via the TLR4-mediated NF-κB (p65) and MAPK (p38) signaling pathways. These findings provide a chemical-biological foundation for the potential application of CSWP-80 as a natural antioxidant and immunostimulant.