Isolation, Structural Characterization, and Hypoglycemic Activities In Vitro of Polysaccharides from Pleurotus eryngii

Abstract

<i>Pleurotus eryngii</i> (PE) is an edible mushroom with high nutritional value. <i>Pleurotus eryngii</i> polysaccharides (PEPs) are one of the main active ingredients and manifest a great variety of biological activities. This study mainly focused on the chemical characterization and biological activities of PEPs, which were separated into two fractions (named WPS and P-1). WPS is mainly dominated by <i>β</i>-glycosidic bonds and contains <i>α</i>-glycosidic bonds, and P-1 only contains <i>α</i>-glycosidic bonds. The molecular weights of WPS and P-1 were 4.5 × 10⁵ Da and 2.2 × 10⁴ Da. The result of GC indicated that two the fractions were composed of rhamnose, arabinose, xylose, mannose, glucose, and galactose, with a ratio of 0.35:0.24:0.45:0.24:28.78:1.10 for WPS and 0.95:0.64:0.66:1.84:60.69:0.67 for P-1. The advanced structure studies indicated that the two fractions had no triple-helical structure, where WPS had a dense structure and P-1 had a loose structure. In addition, the antioxidant activity of WPS surpassed P-1, and the two fractions also exhibited a high hypoglycemic activity via inhibiting <i>α</i>-glycosidase activities and promoting the expression of PI3K-AKT signaling pathway based on in vitro assay and cell experiments.