Structural Characterization and Immunomodulatory Effects of Polysaccharide PCP‐1 from Pleurotus citrinopileatus

Abstract The use of fungal polysaccharides as immunomodulators has garnered significant interest. Here, the polysaccharide PCP‐1 is isolated and purified from the fruiting bodies of Pleurotus citrinopileatus . PCP‐1 is identified as a glucan with a molecular weight of 1670 kDa. Methylation analysis reveals that PCP‐1 consists of T‐Glc p , T‐Rha p , 1,3‐Glc p , 1,4‐Glc p , 1,4,6‐Glc p , and 1,3,6‐Glc p . PCP‐1 exhibits exceptional immunomodulatory effects, as it can dose‐dependently stimulate phagocytosis and promote the secretion of nitric oxide and reactive oxygen species in RAW264.7 cells. Additionally, PCP‐1 significantly enhances the secretion of cytokines such as TNF‐ α , IL‐1 β , and IL‐6 at both the protein and mRNA levels, with concentrations ranging from 2.5 to 40 µg mL −1 . At a concentration of 40 µg mL −1 , the immunomodulatory effects are comparable to those of the positive control. Furthermore, PCP‐1 promotes the nuclear translocation of the p65 protein, indicating activation of the NF‐κB signaling pathway. The results demonstrate that PCP‐1 has the potential as a natural immunomodulator, with possible applications in the food, pharmaceutical, and other industries.