Effects of different extraction techniques on physicochemical properties and activities of polysaccharides from comfrey (Symphytum officinale L.) root

Comfrey (Symphytum officinale L.) has long been used in folk medicine due to its effects of anti-inflammatory and acesodyne. The present study was designed to evaluate the effects of extraction techniques on the physicochemical properties and activities of polysaccharides from comfrey root (CRPs). CRPs were extracted by using four methods including hot water extraction (HW), ultrasonic assistance extraction (UA), enzyme assistance extraction (EA) and enzyme-ultrasonic assistance extraction (EUA). The results showed that CRPs extracted by EUA method (EUA-CRPs) had the highest extraction yield of 24.51%. HPLC analysis presented that the monosaccharide compositions of the four CRPs were indentical, but the monosaccharide content was significantly different. EUA-CRPs had better antioxidant activity, which might be related to its smaller molecular weight and higher content of uronic acid. EUA-CRPs exhibited notable a-glucosidase inhibition activity. The results suggested that enzyme-ultrasonic assistance technology was a good way to extract polysaccharides from comfrey root.