Purification, in-depth structure analysis and antioxidant stress activity of a novel pectin-type polysaccharide from Ziziphus Jujuba cv. Muzaoresidue

Ziziphus Jujuba cv. Muzao has attracted researchers for a long time, while residue of jujuba after extracted by water still contains many bioactivities. This paper presents the first study on in-depth structure analysis and its antioxidant of a pectic polysaccharide (PZJRP) separated and purified from Ziziphus Jujuba cv. Muzao residue through alkali extraction. Results of structural and morphological characterization according to high-performance gel-permeation chromatography, methylation analysis and partial acid hydrolysis etc. showed that PZJRP was composed of rhamnose, arabinose, glucose, galactose and galacturonic acid. Main chain of PZJRP including 1,2,4-linked rhamnose and 1,4-linked galacturonic acid, branches attached to C-4 of rhamnose, which suggested that PZJRP was a pectin polysaccharide belongs to rhamngalacturonan I type (RG-I). Significant antioxidant activity of PZJRP was revealed by protecting RAW264.7 cells against H 2 O 2 -induced oxidative stress. These findings demonstrated the potential of PZJRP to be a functional thickener as a novel food additive.