Radical Scavenging and Low - Density Lipoprotein Cholesterol Oxidation Inhibitory Effects of Polysaccharides Extracted from Chinese Yam, Pumpkin, and Shiitake

The inhibitory effects of three polysaccharides from Chinese yam (Dioscorea opposita), pumpkin (Cucurbita pepo L. var. Kintoga Mak), and shiitake (Lentinula edodes) on the oxidation of low-density lipoprotein cholesterol (LDL) were studied. The molecular weights of the Chinese yam polysaccharide (CP), pumpkin polysaccharide (PP), and shiitake polysaccharide (SP) were 17318 Da, 16619 Da and 14977 Da, respectively. The results of GC-MS showed that all three polysaccharides had mannose and glucose in their monosaccharide composition. FTIR and NMR showed that the three polysaccharides had typical characteristic peaks. The three polysaccharides demonstrated potent in vitro antioxidant activity, among which CP was the best, with IC50 values for DPPH, superoxide, and hydroxyl radical removal ability of 1.06, 1.06, and 0.98 mg/mL, respectively. All three polysaccharides effectively delayed the formation of conjugated diene (CD) in LDL oxidation induced by CuSO4 and significantly inhibited the production of thiobarbituric acid reactive substances (TBARS). At a concentration of 1.0 µg/mL, CP, PP, and SP inhibited TBARS production at rates of 16.28%, 19.38%, and 26.36% of the CuSO4 group, respectively (P > 0.05). The electrophoretic patterns of LDL glycated products showed that PP strongly inhibited the production of glycated products. The present study may provide useful information for understanding the inhibitory effects of polysaccharides on LDL oxidation.