Optimisation of high-pressure ultrasonic-assisted extraction and antioxidant capacity of polysaccharides from the rhizome of Ligusticum chuanxiong

High-pressure ultrasound-assisted extraction was used to extract polysaccharides from the Ligusticum chuanxiong rhizomes. Three independent variables, namely, extraction temperature (X1), ultrasonic power (X2) and extraction time (X3) were investigated. Response surface methodology was performed based on the results of single-factor tests. Experimental data were fitted to a second-order polynomial equation using multiple regression analysis, and results were examined using appropriate statistical methods. The optimal conditions were as follows: extraction temperature of 85 °C, ultrasonic power of 187 W and extraction time of 29 min. Under these conditions, the experimental yield of polysaccharides was 5.33%, which is close to the predicted yield of 5.41%. The extracted and purified polysaccharides showed excellent antioxidative effects on 2,2-diphenyl-1-picryl-hydrazy, hydroxyl and superoxide radicals in vitro.