Primary structure characterization and antioxidant activity of polysaccharide from Zizyphus jujuba cv. Banzao

Objective: This study aimed to analyze the physicochemical properties, primary structure and antioxidant activity of polysaccharide from Zizyphus jujuba cv. Banzao. Methods: The polysaccharides were prepared by water extraction and alcohol precipitation, deproteinization with trichloroacetic acid and decolorization with hydrogen peroxide. The physicochemical properties of polysaccharides were studied, and the possible structures were predicted by Ultraviolet-visible (UV-Vis) and infrared (IR) spectroscopy. Finally, the free radical scavenging ability was determined. Results: The polysaccharide from Z. jujuba cv. Banzao contained the content of total sugar and uronic acid with 52.30% and 46.22%, respectively, and showed 64.70% of esterification degree, which was an acidic pectin polysaccharide; UV-VIS and IR spectroscopy showed that the polysaccharide from Z. jujuba cv. Banzao had typical polysaccharide absorption peak, and contained no protein or nucleic acid. It was a pyranose with α-glycosidic bond, mainly composed of galacturonic acid, galactose, arabinose, glucose. The polysaccharides from Z. jujuba cv. Banzao displayed certain antioxidant activity and the free radical clearance of the polysaccharide at 1 mg/mL for DPPH radical, ·OH and ABTS+· were 23.64%, 21.01% and 13.84%, respectively. Conclusion: The polysaccharide from Z. jujuba cv. Banzao was an acidic pectin sugar mainly composed of galacturonic acid. Besides, it had α-glycosidic bond and showed strong antioxidant capacity, which can be used as a potential antioxidant.