Influences of extraction methods on physicochemical characteristics and activities of Astragalus cicer L. polysaccharides

The aim of this study was to assess the influences of extraction methods on the physicochemical characteristics and antioxidant activities of polysaccharides from Astragalus cicer L. (ACPs). Four methods were applied to ACPs extraction: hot water extraction (HW), ultrasonic-assisted extraction (UA), enzyme-assisted extraction (EA) and enzyme-ultrasonic-assisted extraction (EUA). The ACPs extracted by different techniques were correspondingly named HW-ACPs, UA-ACPs, EA-ACPs and EUA-ACPs. The results indicated that EA-ACPs had higher extraction yields (13.91%). The HPLC results showed that the monosaccharide contents of the four ACPs were significantly different. The ACPs presented antioxidant abilities in a concentration-dependent manner. The higher uronic acid content and smaller molecular weight of the EA-ACPs might contribute to the higher antioxidant activities of EA-ACPs among the four ACPs. These results indicated that enzyme-assisted technology can improve ACPs yields and obtain ACPs with higher antioxidant activities.