Structural Characterization and Hypoglycemic Function of Polysaccharides from Cordyceps cicadae

The polysaccharides isolated and purified from different parts of the medicinal fungusCordyceps cicadaewere identified, and three extracts displaying significant biological activities were selected for further study. The bacterium substance polysaccharides (BSP), spore powder polysaccharides (SPP), and pure powder polysaccharides (PPP) were separated, purified, and collected from the sclerotia, spores, and fruiting bodies ofCordyceps cicadae, respectively. The structures ofCordyceps cicadaepolysaccharides were analyzed using gas chromatography, Fourier-transform infrared spectroscopy, methylation analysis, and one-dimensional (1H and13C) nuclear magnetic resonance spectroscopy. Moreover, the hypoglycemic effect ofCordyceps cicadaepolysaccharides was examined in both in vitro and in vivo models. BSP, SPP, and PPP significantly increased glucose absorption in HepG2 cells, and alleviated insulin resistance (IR) in the in vitro model. SPP was the most effective, and was therefore selected for further study of its hypoglycemic effect in vivo. SPP effectively improved body weight and glucose and lipid metabolism in type 2 diabetes model mice, in addition to exerting a protective effect on liver injury. SPP regulated the mRNA expression of key PI3K/Akt genes involved in the insulin signaling pathway. The hypoglycemic mechanism of SPP may reduce hepatic insulin resistance by activating the PI3K/Akt signaling pathway. Spore powder polysaccharides (SPP) extracted fromCordyceps cicadaeeffectively improved body weight and glucose and lipid metabolism in type 2 diabetes model mice, in addition to exerting a protective effect on liver injury. The mechanism underlying the hypoglycemic effect of SPP regulates the mRNA expression of key PI3K/Akt genes involved in the insulin signaling pathway to alleviate insulin resistance. Our results provide a theoretical basis for research into the hypoglycemic effect ofCordyceps cicadae, and lay the foundation for the development of functional products.Keywords:Cordyceps cicadae;polysaccharides;structural characteristics;HepG2 cells;insulin resistance