Structural properties and hypoglycaemic activity of polysaccharides extracted from the fruits of Lycium barbarum L. using various extraction media

The physical and chemical changes that occur during the preparation of polysaccharides are accompanied by changes in structure and biological activity. Different extraction media can affect the bioactivity of polysaccharides by altering their structural properties, including 1D composition, 2D conformation, and 3D morphology. In this study, polysaccharides from the fruits of Lycium barbarum L. were comparatively extracted using water (LBPs-W), 0.1 M HCl (LBPs-Ac), 0.1 M NaOH (LBPs-Al), 0.1% enzyme (LBPs-E), and 6% ionic liquid (LBPs-ILs) aqueous solution, respectively. The physicochemical properties and structures of the five LBPs were compared, and significant differences existed in their chemical components, monosaccharide composition, molecular weight distribution, glycosidic bond ratio, molecular conformation, and morphology. Of note, LBPs-ILs had the highest α-glucosidase, α-amylase, and aldose reductase (AR) inhibitory activities, which may be related to the different monosaccharide compositions, high branching degrees, rich porous structure, and triple helix structure. These results indicated that different media induce differences in structure and function in the process of polysaccharide extraction and dissolution. In addition, ILs are a promising and practical medium to extract hypoglycaemic LBPs from the fruits of Lycium barbarum L. and may be used to extract polysaccharides from other plant resources.