Studies On Isolation, Purification, Structure And Function Of Polysaccharides From Lotus Leaves

In recent years, lotus leaves as new resource were researched hotly. There were alot of active substances beneficial to body health, such as bioactive polysaccharides,flavonoids and so on. Most researches of lotus leaves were focused on extractingsolution, flavonoids, alkaloid and volatility prepared oil extracted from them, fewwere reported on polysaccharides extracted from lotus leaves.The contents of polysaccharides, flavonoids, proteins, fats, several humanessential elements such as calcium, magnesium, manganese, zinc, copper, Iron andthe composition and percentage of fatty acid in lotus leaves of GuangChang JiangXiprovince were determined. This research provides scientific reference for the furtherstudy and development of lotus leaves as a natural plant resources in China. Besides,it enriches the theory of food chemistry and food nutrition.The color of polysaccharide in lotus lesves, black and brown is major obstaclesfor isolation and purification of polysaccharides and research of chemical structuremechanism and structure-activity relationship. The following six methods for removalof the pigments in the polysaccharide solution were investigated, including hydrogenperoxide bleaching, ethanol alcohol sinks a time, AB-8 resin adsorption, and thecombination of hydrogen peroxide and ethanol alcohol, AB-8 resin and ethanolalcohol combined, AB-8 resin combination of hydrogen peroxide. The single factorand orthogonal experiment were done to optimize the conditions of decolorization.Research found that the resin AB-8, the pH value 6, T=55℃, 3hours thedecolorization rate of polysaccharide solution can be better achieved. The pigments inthe leaves may be mainly due to the negative polarity small molecule-based pigment.In order to study the physical and chemical nature and composition of activitypolysaccharide which were extracted from lotus leaves in pilot extraction, thepolysaccharide solution were deposited by ethanol alcohol, decolored and removedprotein, then polysaccharide L was achieved. Compared three isolational andpurificational technicals of polysacchrides L, and then make sure a sort of bettermethod. L1 and L5 were achieved by isolation and purification with DEAE SephadexA-25 cellulose. LP1, LM1, LP5, LM5 were achieved by further purified with Sephacryl S-200 gel column, and the molecular weight were measured by SephacrylS-200 gel filtration for 105468, 103657, 95693, 90415. Then LM1 and LM5 wereexamined as homogeneous polysaccharides by Sephacryl S-300. The infrared spectraof LM1, LM5 show typical characteristic absorption peaks; LM1, LM5 for GCanalysis showed that at least rhamnose, arabinose, xylose, mannose, glucose,six-galactose monosaccharide components.The functional properties of polysaccharides L, including anti-oxidation in vitroexperiments and inhibition experiments. And the relationship with bovine serumalbumin wre investigated. The effect of remove·OH and O₂·is relatively low, while itcan remove Bitterness of diphenyl-radical (DPPH), and the linoleic acid oxidationwas determined by thiobarbituric acid (TBA). Its better inhibition effect toStaphylococcus aureus and Rhizopus were showed by eight pathogens inhibitionexperiments. It has Fluorescence quenching to Bovine serum albumin obviously.