Abstract: The composition and in vitro antioxidant activity of polysaccharides extracted from Chinese yam (Dioscorea opposite Thunb.) were analyzed. Additionally, we tested whether the polysaccharides could inhibit the oxidation of low-density lipoprotein (LDL). The results showed that the purity of the polysaccharides was (65.79 ± 1.03)%, which also contained (5.89 ± 0.43)% protein, (5.51 ± 0.14)% ash and (10.81 ± 1.14)% uronic acid. The molecular masses of the four main polysaccharide components were 933 742, 148 878, 39 233, and 17 318 Da, respectively. The half maximal inhibitory concentration (IC50) values for 1,1-diphenyl-2-picrylhydrazyl (DPPH), superoxide, and hydroxyl radical scavenging activity were 1.06, 1.06 and 0.98 mg/mL, respectively. The polysaccharides effectively delayed the formation of conjugated diene during LDL oxidation induced by CuSO4. At a concentration of 1.0 μg/mL, the polysaccharides inhibited 16.28% thiobarbituric acid reactive substance (TBARS) production induced by CuSO4 (P > 0.05), but had little inhibitory effect on LDL glycation. The results of the present study may provide useful information for understanding the inhibitory effects of Chinese yam polysaccharides on LDL oxidation.

Key words: Chinese yam polysaccharides; antioxidant; low-density lipoprotein; glycation