Comparison of characterization, antioxidant and immunological activities of three polysaccharides from Sagittaria sagittifolia L.

To investigate and compare the preliminary structural characteristics and biological activity in vitro of polysaccharides from Sagittaria sagittifolia L. (SSs) by different extration methods, three polysaccharides (SSW, SSU, and SSP) were obtained with hot water, ultrasound-assisted, and subcritical water extraction. Their structural features were elucidated using High Performance Liquid Chromatography (HPLC), Gas Chromatography (GC), Scanning Electron Microscopy (SEM), Infrared Spectroscopy (IR), Atomic Force Microscopy (AFM), Zeta Potential and Congo red methods. Furthermore, the antioxidant activity and immunostimulatory effects were investigated in vitro. Molecular weight and monosaccharide composition analysis exhibited that SSW (2275.0 kDa), SSU (148.7 kDa), and SSP (1984.0 kDa) were heteropolysaccharide with dramatically different monosaccharide species and mole ratios. In addition, SSP exhibited stronger antioxidant activity in vitro and more potent immunomodulatory activity than SSW and SSU. SSP has greater potential to be explored as biologicalagents for use in complementary medicine or functional foods.