Extraction,Purification,Characterization And Antioxidant Activities Of Polysaccharides From Ziziphus Jujuba Cv.Hamidazao

Polysaccharides are one of the important active ingredients in jujube.They have multiple biological activities such as anti-oxidation,anti-inflammatory,liver protection and anti-cancer,and they can be widely used in functional health foods.The nutritional and health value of Z.jujuba cv.Hamidazao ranks among the top jujubes in the world due to special climatic conditions.However,there is no report on the extraction,purification and structural characterization of the polysaccharides from Z.jujuba cv.Hamidazao.We conjectured that the polysaccharides from Z.jujuba cv.Hamidazao differed from those from other jujube varieties and they were bio-macromolecules composed of multiple fractions with different structures and health benefits.Therefore,it is quite necessary to comparatively analyze the profile,structure and biological activity of different polysaccharides from Z.jujuba cv.Hamidazao.（1）Optimization of the extraction process of polysaccharides from Z.jujuba cv.Hamidazao:Using response surface methodology to optimize the ultrasonic extraction process the polysaccharides from Z.jujuba cv.Hamidazao.The optimal process parameters were ultrasonic power 200 W,ultrasonic time 24 min,liquid-to-material ratio 16:1 m L/g,ultrasonic temperature 48°C,and the yield is（3.11±0.45）%.The main effect of ultrasonic temperature and liquid-to-material ratio was significant,the liquid-to-material ratio has the greatest influence on the extraction rate of polysaccharides,followed by ultrasonic temperature and ultrasonic time have the least influence on the extraction rate of polysaccharides.（2）Isolation and Purification of Polysaccharides from Z.jujuba cv.Hamidazao:HJP was separated and purified by DEAE-52 cellulose column and Sephadex G-100 dextran gel column chromatography to obtain fourcomponents including HJP-1a,HJP-2,HJP-3 and HJP-4.（3）Structural Characterization of Polysaccharides from Z.jujuba cv.Hamidazao:The monosaccharide composition and molecular weight of the polysaccharide component were determined by HPAEC and HPGPC-MALLS/RID.The results showed that:HJP-1a was mainly composed of arabinose and galactose in a ratio of 56.93∶19.99,with an average molecular weight of 3.115×10⁴Da.HJP-2,HJP-3 and HJP-4 were homogeneous hetero-polysaccharides mainly containing galacturonic acid,arabinose and galactose,with average molecular weights of 4.590×10⁴Da,6.986×10⁴ Da and 1.951×10⁵ Da,respectively.Structural characterization indicated that the backbone of HJP-3 appeared to be mainly composed of→4)-α-D-Galp A（1→and→2,4）-α-L-Rhap（1→residues with some branches consisting of→5）-α-L-Araf(1→residues and terminals of T-α-L-Araf(1→and T-β-D-Galp residues.（4）Study on Antioxidant Activity of Polysaccharide from Z.jujuba cv.Hamidazao:The antioxidant activity of different purified polysaccharides was analyzed by experiments in vitro and in vivo,The four purified fractions displayed dose-dependent radical scavenging activity on ABTS⁺radicals and reducing capacity,as well as excellent protective effect on H₂O₂-induced Hep G2 cells and metronidazole-damaged zebrafish embryos,especially HJP-2 in vitro and HJP-1a in vivo.Therefore,the polysaccharides from Z.jujuba cv.Hamidazao could be used as a potential antioxidant in functional foods.The present conclusions showed that the four purified fractions extracted from Z.jujuba cv.Hamidazao had in vitro and in vivo antioxidant which could protect the body against the oxidative stress and decline the aging process.which provided a basis for the development and application of the polysaccharides from jujube.