Study On Extraction,Purification And Antioxidant Activity Of Proanthocyanidins From Jujube

China is the hometown of jujube.Its planting area and output rank the first in the world,and the development of jujube products has unique advantages.Jujube is one of the main fruit tree in Hengyang area of Hunan Province.In order to promote the utilization of jujube fruit resources in Hengyang area of Hunan province and to excavate the germplasm resources of Chinese jujube trees.In this experiment,The content of proanthocyanidins in different jujube varieties was determined with the content of proanthocyanidins as the main index,and the extraction,purification and antioxidant activity of jujube proanthocyanidins were studied.The main results are as follows:（1）The content of proanthocyanidins in different varieties of jujube fruits was determined by ferric salt catalytic colorimetry,using 14 Jujube Cultivars in Hengyang area of Hunan Province as raw materials.The results showed that the content of proanthocyanidins in different varieties of jujube was very different.The difference between the highest and the lowest proanthocyanidins between different jujube varieties is 3.61 times.The varieties with high content of proanthocyanidins in jujube were Qidong jidan jujube,Hengnan zidan head,Hengnan longxu jujube,and Qidong suanpan jujube,among which the content of proanthocyanidins in fresh fruit of Qidong jidan jujube was up to 6.86 mg/g.（2）Based on single factor,Box-Behnken technology and response surface analysis were used to optimize the extraction process of jujube proanthocyanidins.The optimum parameters are obtained:ultrasonic time 16 min,ultrasonic power 618 W,ultrasonic temperature 65 C,and the ratio of material and liquid at 1:21,the extraction yield of jujube proanthocyanidins can reach 1.82%.（3）By comparing the physical structure,adsorption and desorption of six resins,AB-8resin was selected to purify jujube proanthocyanidins.hrough static and dynamic tests,the optimum purification process parameters are as follows:the pH value of the sample is 5,the amount of the upper sample is 1.5 BV,the alcohol eluant and the eluant are used for 2.5times the volume of the column,and the purity of proanthocyanidin powder is 73.07%.By measuring the reduction ability of jujube proanthocyanidins,the scavenging ability of DPPH free radical and the scavenging ability of hydroxyl radical,the experiment showed that the reduction ability of the purified substance,the scavenging ability of DPPH free radical and hydroxyl radical were higher than that of Vc.And the ability of scavenging DPPH free radicals of jujube proanthocyanidins is higher than that of hydroxyl radicals.（4）The purified jujube proanthocyanidins were fractionated by ethyl acetate and polyamide,and the antioxidant capacity of each acetone elution product was compared.The results showed that ethyl acetate and polyamide could achieve the purpose of fractionation of purified jujube proanthocyanidins.The acetone elution products of 30%,50%and 70%were obtained,and the average polymerization degree was 2.07,3.26 and 3.47 respectively.The degree of polymerization increased with the concentration of the eluent acetone.he antioxidant capacity of procyanidins with different polymerization degrees was quite different.The antioxidant activity of procyanidins（D1）with two polymerization degree is better than that of monomer proanthocyanidins.With the increase of polymerization degree,the antioxidant capacity of procyanidins gradually weakened.The oxidation resistance of proanthocyanidins with the same polymerization degree is directly proportional to the concentration.（5）We used the purified of jujube proanthocyanidin to protect HaCaT cells,and hydrogen peroxide（H₂O₂）acts on HaCaT cells to induce oxidative damage.The protective effects of jujube proanthocyanidins on oxidative damaged HaCaT cells were investigated by measuring apoptosis,ROS level,superoxide dismutase（SOD）,and glutathione peroxidase（GSH-Px）activity.The results showed that hydrogen peroxide could induce oxidative damage and apoptosis in HaCaT cells.However,jujube proanthocyanidins can increase the activity of GSH-Px and SOD,decrease the activity of oxygen and decrease the rate of apoptosis of HaCaT cells,and protect cells from oxidative stress.