A novel polysaccharide from Pleurotus citrinopileatus mycelia: Structural characterization, hypoglycemic activity and mechanism

Pleurotus citrinopileatus(P. citrinopileatus) is a precious medicinal fungus. A novel polysaccharide (CMP) was separated from the mycelia of P. citrinopileatus. The CMP is a neutral polysaccharide with Mw of 3.22 x 10(6) Da. The CMP is composed of D-Mannose, D-Glucose and D-Galactose with molar ratio of 0.33:1.03:0.21. The backbone of CMP is composed of -> 3)-alpha-D-Glcp-(1 -> and -> 3, 6)-alpha-D-Glcp-(1 ->, while branches contain -> 3)-alpha-D-Manp-(1 -> and -> 3)-beta-D-Galp-(1 -> . The surface morphology of CMP is smooth with irregular fragmented structure. The IC50 value of CMP is 0.371 mg/mL. Compared with acarbose (0.289 mg/mL), it suggest that CMP has effectively inhibition on alpha-glucosidase and the inhibition type is Mixed Type inhibition. The CMP can significantly promote the uptake of glucose and the synthesis of glycogen to regulate the insulin resistance of HepG2 insulin resistance cells (HepG2-IR). The regulation of insulin resistance in HepG2-IR cells by CMP is through Pi3K/Akt pathway. The manuscript provide the alternative of polysaccharides from P. citrinopileatus fruiting bodies and develop new substance for hypoglycemic food.