Sulfated modification, characterization and antioxidant activities of polysaccharide from Cyclocarya paliurus

In this study, polysaccharide extracted from Cyclocarya paliurus was chemically modified to obtain its sulfated derivatives. The physicochemical characterizations and antioxidant properties of these sulfated polysaccharide derivatives were comparatively investigated by chemical methods, circular dichroism spectra, high-performance anion exchange chromatography, high-performance gel permeation chromatography, fourier transform infrared spectrometry, and hydroxyl radical assay, DPPH radical assay, superoxide radical assay and β-carotene–linoleic acid assay, respectively. Results showed that these modifications were successful, and the physicochemical and antioxidant properties of polysaccharides were changed after sulfation. Among these sulfated polysaccharides, the S-CP1–8 with relatively the lowest degree of substitution (DS), molecular weight (Mw) and the highest protein content exhibited excellent antioxidant activities in hydroxyl, superoxide, DPPH radical assay and β-carotene–linoleic acid assay. These results indicated that the in vitro antioxidant activities of the sulfated polysaccharides from Cyclocarya paliuru may be related to combined effects of DS, Mw, sulfate content, protein and uronic acid content.