Extraction optimization, physicochemical properties and antioxidant and hypoglycemic activities of polysaccharides from roxburgh rose (Rosa roxburghii Tratt.) leaves

The optimum extraction conditions of polysaccharides from roxburgh rose (Rosa roxburghii Tratt.) leaves (RLP) were obtained by response surface methodology (RSM), which were a liquid to solid ratio of 21.16 mL/g, an extraction temperature of 81.32 °C, and an extraction time of 90.49 min. An RLP yield of 11.04% was obtained under these conditions. DEAE-52 cellulose and Sepharose CL-6B columns were used to purify the RLP, and the purified polysaccharide components RLP-1.2 and RLP-2.1 were obtained. Both RLP-1.2 and RLP-2.1 were composed of galacturonic acid (GalA), glucose (Glc), galactose (Gal), and arabinose (Ara). However, the molar ratios of GalA, Glc, Gal, and Ara in RLP-1.2 and RLP-2.1 were different. At a concentration of 10 mg/mL, the α-amylase inhibitory activities of RLP-1.2 and RLP-2.1 reached 80.74% and 89.85% that of acarbose, respectively, and the α-glucosidase inhibitory activity of RLP-1.2 reached 87.91% that of acarbose. In addition, both RLP-1.2 and RLP-2.1 showed good antioxidant activity. These results suggested that RLP-1.2 and RLP-2.1 possess potential as natural hypoglycemic agents or natural antioxidants.