Structural characterization and antioxidant activities of polysaccharides from Angelica dahurica as extracted by optimized ultrasonic-assisted method

The study aimed to select the best extraction technology of Angelica dahurica polysaccharides (ADP), characterize its structure, and antioxidant activity. On the basis of the single-factor experiment result, the ultrasonic-assisted extraction (UAE) of ADP was ameliorate using the response surface method. The optimal conditions were: extraction time 32 min, extraction temperature 74 degrees C, ratio of water to material 19 mL/g, extraction power 270 W. The practical extraction rate was 11.21 +/- 0.12% (g/g). C-1: Not clear?? g/s??? ADP was purified by column chromatography, and then three polysaccharide fractions (ADP-H, ADP-0.1 and ADP-0.3) were obtained using DEAE-Cellulose 52. The ADP was mainly composed of D-Mannose, D-Glucose, D-Galactose, L-Arabinose, the ADP-H was mainly composed of D-Mannose, D-Glucose, D-Galactose, L-Arabinose, the ADP-0.1 was mainly composed of D-Mannose, D-Galacturonic acid, D-Glucose, D-Galactose, L-Arabinose, and the ADP-0.3 was mainly composed of D-Mannose, L-Rhamnose, D-Galacturonic acid, D-Galactoe, L-Arabinose. The molecular weights of ADP-H, ADP-0.1 and ADP-0.3 were 1.01 x 10(4) Da, 1.45 x 10(7) Da and 6.96 x 10(6) Da. In addition, the purified polysaccharides have certain scavenging ability of DPPH free radical, hydroxyl free radical and ferric reducing power, which can be used as natural products of antioxidants.