Study on the chemical modification of polysaccharides from Helvella leucopus and the structure-activity relationship...

Polysaccharides extracted from edible and medicinal fungi have attracted much attention due to their various biological activities, including their antioxidant and hypoglycemic effects. Helvella leucopus, a wild mushroom species valued for its high economic, nutritional, and health-promoting potential, has drawn increasing interest in recent years. In this paper, polysaccharide (HLP) from H. leucopus was extracted using 1-ethyl-3-methylimidazolium bromide (EMImBr) combined with ultrasound, followed by purification through ethanol precipitation, deproteinization via the Sevage method, dialysis, DEAE-52 ion-exchange chromatography, and Sephadex G-100 gel column chromatography to obtain homogeneous components. We show that HLP and its chemically modified derivatives have significant differences in monosaccharide composition and molecular weight, but they have similar infrared spectroscopy (FT-IR) and X-ray diffraction pattern characteristics. Scanning electron microscopy revealed a significant change in the surface morphology of the derivatives. Our data indicate that HLP and its derivatives all exhibited good antioxidant activity and hypoglycemic activity. In particular, compared with natural HLP, its chemically modified derivatives exhibit significantly enhanced biological activities, specifically manifested as stronger free radical-scavenging ability and higher inhibitory activities against $\alpha$ -glucosylase and $\alpha$ -amylase. In conclusion, chemical modification can significantly enhance the biological activity of HLP. Our data provide an important theoretical basis for clarifying the structure-activity relationship of polysaccharides and further developing highly efficient antioxidant or hypoglycemic functional foods/drugs based on HLP.