Structural characterization, antioxidant activity, and mechanism of polysaccharides isolated from Dictyophora...

Dictyophora rubrovalvata is a valuable edible fungus. Its stipe, is rich in polysaccharides, possesses potential biological activity and medicinal value. In this study, we isolated a new polysaccharide, DRP-L, from the stipe of D. rubrovalvata, characterized its structure, and used PC12 to examine its antioxidant effect and mechanism. The results of structural analysis showed that the molecular weight of DRP-L was approximately 2.14 × 10³ kDa. The monosaccharide composition included D-galactose, D-mannose, and d-glucose with a relative molar ratio of 0.41:1:0.37. In the activity study, in vitro antioxidant experiments demonstrated that DRP-L has commendable antioxidant activity. Simultaneously, DRP-L can protect PC12 cells from oxidative damage by reducing the levels of lactate dehydrogenase (LDH) and malondialdehyde (MDA) and increasing the level of superoxide dismutase (SOD) in a dose-dependent manner, with the best effect at a concentration of 1.6 mg/mL. Western blotting results indicated that DRP-L could shield PC12 cells from H₂O₂-induced oxidative damage by managing the PI3K/Akt signaling pathway, suppressing the expression of Caspase-3 and BAX, and boosting Bcl-2 expression and Akt phosphorylation. In conclusion, with its unique structure and remarkable antioxidant activity, DRP-L offers new insights and directions for developing antioxidants based on natural products.