Abstract: In order to evaluate the effects of different extraction methods on polysaccharides from Hedyotis diffusa Willd in Henan Province,the crude polysaccharides were extracted using hot-water extraction,ultrasound-assisted extraction and cellulase extraction,respectively.Meanwhile,the crude polysaccharide yields,total carbohydrate contents,impurity contents (total protein contents and total protein contents),hydroxyl radical scavenging activity,DPPH radical scavenging activity and reducing ability were measured.The results showed the yields of the three crude polysaccharides were 6.77±0.09%,6.37±0.01% and 4.81±0.90%,respectively.The total carbohydrate contents in three crude polysaccharides were 289.14±1.33,246.83±2.33 and 278.92±2.92 mg/g,respectively.The total protein contents in three crude polysaccharides were 28.59±2.21,23.26±2.43 and 4.96±0.18 mg/g,respectively.Additionally,the total phenolic contents in three crude polysaccharides were 5.9±0.08,5.31±0.40 and 2.82±0.07 mg/g.The antioxidant activity results showed that the hydroxyl radical scavenging activity of the three crude polysaccharides were concentration-dependent and the scavenging ability of all samples reached the maximum rates of 89.13%,85.87% and 74.71% at 3.0 mg/mL,respectively.Furthermore,DPPH radical scavenging rates of all samples reached the maximum and remained stable within the concentration range of 0.75-3.0 mg/mL.The corresponding stable ranges of scavenging rates were 77.02%-77.90%,77.06%-77.96% and 83.16%-8573%,respectively.In conclusion,different extraction methods have great influence on polysaccharide characteristics of H.diffusa Willd,which could be used for the identification,quality control and comprehensive utilization of H.diffusa Willd in Henan Province.

Key words: Hedyotis diffusa Willd, extraction methods, polysaccharide, antioxidant activity