Optimization of Water-Soluble Polysaccharides Extraction from Rhizome of Polygonatum odoratum Using Response Surface Methodology and Its Antioxidant Activities in Vitro

A Box-Behnken design was used to optimize the extraction conditions of water-soluble polysaccharides(POP) from Polygonatum odoratum(Mill.) Druce.Three factors such as extraction time(h),extraction temperature(℃) and ratio of water to raw material were investigated.The experimental data were fitted to a second-order polynomial equation using multiple regression analysis and also examined using the appropriate statistical methods.The optimum extraction conditions were listed as follows:extraction time 2.24 h,temperature 88.35 ℃,and ratio of water to raw material 35∶1 mL/g,the predicted yield of polysaccharides extracted was 8.47%.Under the optimum conditions,the mean extraction yield of polysaccharides was(8.46±0.02).The antioxidant in vitro results showed that the inhibition effects of POP on 2,2-diphenyl-2-picrylhydrazyl free radical,hydroxyl free radical and superoxide anion radical with IC50 values were 0.646,10.029,0.241 mg/mL,respectively,which were higher than 0.048,0.238,0.078 mg/mL of ascorbic acid,respectively.POP showed significant inhibitory effects on hydrogen peroxide with IC50 value of 0.541 mg/mL,which was lower than 0.901 mg/mL of ascorbic acid.