Structural characterization, rheological characterization, hypoglycemic and hypolipidemic activities of polysaccharides from Morchella importuna using acidic and alkaline deep eutectic solvents

During the preparation of polysaccharides (PSs), rheological characterization and bioactivities of PSs are affected by diverse extraction media through changing their structural properties. In this study, PSs were extracted comparatively from Morchella importuna (MIPs) with deep eutectic solvents (DESs) including an acidic deep eutectic solvent (MIP-AC) and an alkaline deep eutectic solvent (MIP-AL), respectively. The physico-chemical properties, rheological properties, and hypoglycemic and hypolipidemic activities of the MIPs were then studied. The results showed that DESs as an extraction medium could not only significantly increase the extraction yield of MIPs but also increase the contents of carbohydrates and sulfuric acid groups in MIPs. Moreover, DESs treatment could change the glycosidic linkage type and surface morphology of MIPs, reduce the molecular weight and viscosity of MIPs, and improve the system stability of MIPs, thus affecting the rheological properties and hypoglycemic and hypolipidemic activities of MIPs. It is worth noting that MIP-AL possessed stronger hypoglycemic and hypolipidemic activities, which was reflected by its roles in inhibiting the activities of α-glucosidase and α-amylase, increasing glucose consumption, and reducing triglyceride and cholesterol contents in Hep G2 cells. This research will provide a theoretical basis for the selection of DESs for extraction of specially appointed PSs.