Structural Characterization and Hypoglycemic Effect of a Polysaccharide from Pleurotus citrinopileatus Mycelia

In this study, the structure of a water-soluble polysaccharide named PCP-W from the P. citrinopileatus mycelia was investigated by high performance size exclusion chromatography (HPSEC) and infrared (IR) spectroscopy. To evaluate the in vivo hypoglycemic effect of PCP-W, the fasting blood glucose level, glucose tolerance and fasting insulin level in mice with type 2 diabetes were measured after gavage administration of PCP-W for eight weeks, the quantitative insulin sensitivity check index (QUICKI) was calculated, and the levels of serum lipids and oxidative stress and the activities of hepatic hexokinase (HK) and pyruvate kinase (PK) were detected. The results showed that the molecular mass of PCP-W, containing D-glucopyranose units, was 5238 Da. PCP-W was composed of mannose, ribose, rhamnose, glucuronic acid, galacturonic acid, glucose, galactose and fucose in a molar ratio of 0.003: 0.010: 0.011: 0.015: 0.001: 0.944: 0.013: 0.001. After eight weeks of treatment with PCP-W, the fasting blood glucose level was reduced, the glucose tolerance was improved, the fasting insulin level was increased, and QUICKI was improved in diabetic mice significantly (P < 0.01). In addition, lipid metabolism and oxidative stress levels were improved, and the activities of PK and HK were increased (P < 0.01). Therefore, PCP-W has the potential to act as a hypoglycemic agent.