Abstract:For the high-value utilization of Xanthoceras sorbifolium seed meal, polysaccharides (XSP) were extracted, purified, and their basic structure was characterized. The in vitro antioxidant and enzyme inhibitory activities were also evaluated. The extraction process was optimized using single-factor and response surface methodology, and XSP was subsequently purified. The contents of total sugar and uronic acid were determined. Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy were used to analyze the glycosidic bonds. The structure was characterized by Congo red experiment, circular dichroism spectroscopy, and X-ray diffraction. Thermal stability was assessed by thermogravimetric analysis (TGA). The bioactivities were evaluated through DPPH?, ?OH, and ABTS+? scavenging assays, as well as α-amylase and α-glucosidase inhibitory assays. The results showed that the optimal extraction parameters were a solid-to-liquid ratio of 1:20 (g·mL-1) , 80 ℃ , 3 h , yielding a polysaccharide yield of 1.59%. The molecular weight of XSP was 1.14 × 107 kDa. The mass fractions of total sugar and uronic acid in XSP were 91.07% and 10.77%, respectively. XSP contained both α- and β-glycosidic bonds, with arabinose and galactose being the predominant monosaccharides. TGA indicated that XSP possessed good thermal stability below 200 ℃. XSP was found to have a triple-helix conformation and semi-crystalline characteristics. Furthermore, XSP exhibited dose-dependent antioxidant and enzyme inhibitory activities. In conclusion, XSP has a stable structure and demonstrates good antioxidant and enzyme inhibitory activities. This study provides a theoretical basis for research on the structure-activity relationship of Xanthoceras sorbifolium seed meal polysaccharides and their potential application in functional food development.
