[Effects of different extraction methods on chemical compositions and biological activities of polysaccharides from...

In this study, five polysaccharides from Lycium barbarum(LBPs)(LBP-1-LBP-5) were selectively extracted by different extraction methods, and the chemical composition, structural characteristics, and biological activities of LBPs were explored. The results of chemical composition analysis showed that alkaloids were not detected in the five LBPs. The total polysaccharide content was(81.95%±1.6%)-(92.96%±0.76%), the uronic acid content was(8.26%±0.46%)-(24.81%±0.46%), and the protein content was(0.06%±0.03%)-(1.35%±0.13%). The monosaccharide compositions of the five LBPs were basically same, mainly including glucose, xylose, and galactose. However, there was significant difference in the content ratio of different monosaccharide. The results of infrared spectra analysis indicated that the five LBPs had typical infrared spectral characteristics of polysaccharides. The results of nuclear magnetic resonance characteristic spectrum analysis revealed that the five LBPs had two configurations of α and β. Meanwhile, there were triple helix structures in LBP-2, LBP-3, and LBP-4, which enhanced the activities of polysaccharides. The results of activities screening suggested that the biological activities of the five LBPs were significantly different. LBP-3 showed the highest lipid oxidation clearance rate, and its antioxidant activity was equivalent to that of the positive control group. The inhibitory rate of LBP-4 on α-amylase and its activation rate of alcohol dehydrogenase were better than those of other fractions, and the inhibitory rate of LBP-4 on α-amylase was slightly higher than that of the positive control group when the mass concentration was 10 g·L~(-1). LBP-2 showed stronger inhibitory activity against α-glucosidase and hyaluronidase. This study provides references for the precise development and utilization of LBPs.