A comparison on Schisandra chinensis polysaccharides extracted by different methods: Structure, physicochemical...

Natural polysaccharides have attracted attention due to their excellent biological activities, with extraction methods exerting a significant impact on the physicochemical properties and bioactivities. In this study, Schisandra chinensis polysaccharides were extracted using three different methods, such as ultrasound-, microwave- and plasma-assisted aqueous two-phase extraction (UA-/MA-/PA-ATPE). Among the three methods, the polysaccharide extracted by PA-ATPE method displayed the highest yield (total 27.68%) than UA-ATPE (total 23.72%) and MA-ATPE (total 19.31%). After purification, six polysaccharides including PUBP-1 (upper) and PUBP-2 (lower) for UA-ATPE, PMBP-1 (upper) and PMBP-2 (lower) for MA-ATPE, PDBP-1 (upper) and PDBP-2 (lower) for PA-ATPE were obtained. Among them, PUBP-1 possessed the lowest molecular weight (96.16 kDa), the best water solubility, physical and thermal stabilities, and moderate uronic acid content and rheological property. Six polysaccharides almost were all heteropolysaccharides composed of Man, Rha, Glc A, Gal A, Glc, Gal and Ara but at different molar ratios. FT-IR, NMR and methylation analyses revealed they exhibited different glycosidic bonds, while T-α-L-Araf-(1→, →6)-α-D-Glcp-(1→, →4)-β-D-Manp-(1→, and →4)-β-D-GalpA-(1→ were the main linkage patterns. PUBP-1 demonstrated the superior antioxidant activity, and inhibitory activity on α-amylase, hyaluronidase, and xanthine oxidase in vitro, likely due to its relatively low molecular weight, suitable solubility, and high uronic acid content. Therefore, extraction method differentially affected the glycoside bonds and linkage patterns, as well as the physicochemical and biological properties of natural polysaccharides. Consequently, Schisandra chinensis polysaccharides may serve as promising natural functional additives in food and pharmaceutical sectors.