Study On Isolation, Purification, Structure And Antioxidant Activity Of Watersoluble Polysaccharide From Moringa Seed

In this paper, physicochemical properties and Antioxidant activity of Moringa Seed polysaccharide fractions were studied, polysaccharide fractions MOP-D were isolated and purified, and the chemical structure and antioxidant activity of two single polysaccharide components were systematacially studied. Fill the research gaps of Moringa Seed polysaccharide in separation and purification, structural characterization and biological activity.(1) Analysed the basic raw material components, mainly protein, total soluble sugars and starch contents, the contents of them were 58.59%, 20.31% and 12.77% respectively. Hot water extraction method was used to extract the Moringa Seed polysaccharide, in the single factor foundation, according to the Box-Benhnken central combination experiment to optimize the extraction process, finally, determined the optimum process parameters of liquid ratio, extraction time, extraction temperature and the polysaccharide extraction rate,they were 55.5 g / m L, 1 h, 79℃ and 14.11% respectively.(2) Studied the deproteinization process of Moringa Seed polysaccharide. Using Sevage, biological enzyme and papain joint Sevage to remove protein of Moringa Seed polysaccharide.Compared three methods of removing protein and drawn a conclusion that papain-Sevage was the best method to remove protein, it had higher polysaccharide retention rate, the removal rate of protein and polysaccharide retention rate were 76.3%, 80.4% respectively. This study was performed using deproteinized papain joint Sevage law.(3) The ethanol fractionation method was uesd to crude separate polysacc harides from Moringa Seed, we can get four polysaccharide fractions, namely MOP-A, MOPB, MOP-C, MOP-D. Through antioxidation experiments in vitro and cell model, we defined that MOP-D is the best antioxidant activity of the four polysaccharide fractions.(4) The MOP-D-a was obtained by DEAE- 52 column chromatography purification of MOP-D, monosaccharide composition analysis results shown that the polysaccharide components were constituted by the L- rhamnose, D- arabinose, Dxylose, D- mannose, D- glucose and D- galactose. The monosaccharide molar ratio was 3.33: 0.48: 0.47: 0.39: 0.75: 1.53.(5) Two single polysaccharides, MOP-D-a-1and MOP-D-a-2, were obtained by Sephadex column chromatographic purification of MOP-D-a. HPLC, IR, UV- visible spectroscopy, experimental method of Congo red, nuclear magnetic resonance spectroscopy analysis were applied to study their structure and physicochemical properties, and their chemical structure characteristics were drown as follo ws: two polysaccharides components both were polysaccharides substances; both of them contained a certain protein; MOP-Da-1 with a triple helix structure, MOP-Da-2 did not have a triple helix structure(6) The test of homogeneous polysaccharide radical scavenging showed that the ability of them when they scavenge the ABTS radical and hydroxyl radical as follows : Vc> MOP-D> MOP-D-a-2> MOP-D-a-1. The differences exhibited in threecomponent polysaccharide on capacity of free radical scavenging may related to the molecular weight of polysaccharide, molecular entanglement, the hydroxyl and amino numbers of polysaccharide molecules.