Extraction, Purification, Characterization, and Bioactive Properties of Polysaccharides from Sphallerocarpus gracilis

Four new polysaccharides, SGP-1-4, are isolated and purified from Sphallerocarpus gracilis (S. gracilis) . The monosaccharide analysis revealed that the isolated polysaccharides are composed of different molar ratios of glucose (Glu), galactose (Gal), rhamnose (Rha), mannose (Man), and arabinose (Ara). Congo red test showed that no triple helical structure is detected in SGP-1-4. The Zeta potentials of SGP-1-4 are negative. The antioxidant activities are evaluated using DPPH and Superoxide radical assays. In vitro antitumor activities are investigated by MTT assay and Calcein-AM/PI staining confocal imaging. The hypolipidemic activities are measured by the bile-salt binding capacity in vitro. The results indicated that SGP-1-4 possessed significant antioxidant and hypolipidemic abilities. At the concentration of 0.2 mg/mL, the purified polysaccharides possess no significant effects against MGC-803 (Human gastric cancer cells), A2780 (Human ovarian cancer cells), T24 (Human bladder cancer cells), CNE-2 (Human nasopharyngeal cancer cells), and 4T1 (Mouse breast cancer cells) tumor cells in vitro. However, the SGP-2 shows potential as a DOX-chemotherapy against 4T1 cells, which indicated that SGP-2 could exert antitumor effects. These findings provide a scientific basis for the further use of S. gracilis polysaccharides as a natural antioxidant, antitumor, and hypolipidemic agent in industry.