A novel acid polysaccharide from fermented broth of Pleurotus citrinopileatus: Hypoglycemic activity in vitro and chemical structure

Abstract

The extracellular polysaccharides are important biological resources with wide application. Pleurotus citrinopileatus(P. citrinopileatus) is a precious medicinal fungus with variously bioactivity. The literatures on the specific components with hypoglycemic effect in crude polysaccharides from fermented broth of P. citrinopileatus and the structure have not been reported. A novel acid polysaccharide (CFP) with Mw of 1.062 × 106 Da was isolated from fermented broth of P. citrinopileatus. The hypoglycemic activity in vitro of CFP and accurately chemical structure were explored. The CFP had effectively inhibition on α-glucosidase with IC50 values of 0.556 mg/mL through non-competitive inhibition. The CFP had no effect on normal growth and proliferation of HepG2 cells but can regulate the insulin resistance in HepG2-IR cells. Simultaneously, the CFP can significantly reduce the oxidative stress in HepG2-IR cells. All the results elucidated that CFP had effective hypoglycemic activity. The structural characterization revealed that CFP was composed of D-Gal, D-Glc, D-GalA and D-GlcA with a percentage of 20.53:28.75:5.55:45.17. The backbone of CFP was composed of →3)-α-D-Glcp-(1→, →3)-α-D-GlcAp-(1→ and →3, 6)-α-D-Glcp-(1→, while branches contained →3)-β-D-GalAp-(1→ and →3)-β-D-Galp-(1 → . The CFP had triple-helix conformation. The surface of CFP was rough and had irregular small fragments with hole-like and stripe-like structure. The manuscript further identified the main carbohydrates components in the fermentation liquid of P. citrinopileatus. It provided basis for the development and utilization of active components in P. citrinopileatus. The structural characterization of polysaccharide can provide experimental basis for exploration of structure-activity relationship.