Preparation and Antioxidant Activity of Aloe Polysaccharide and Its Derivatives

Using fresh aloe as raw material, the polysaccharides were extracted by hot water. Protein in the polysaccharide solution was removed by Sevage method, and then the refined aloe polysaccharide was prepared by dialysis. Finally, the structure and biological activities of polysaccharide derivatives were studied. The molecular weight of aloe polysaccharide was determined by GPC-RI-MALS. The structure of aloe polysaccharide was confirmed by13C NMR. In order to study the structure-activity relationship of aloe polysaccharides, the aloe polysaccharides were derived. The derivatives include acetylated aloe polysaccharides, phosphorylated aloe polysaccharides and carboxylated aloe polysaccharides. The structure characterization showed that aloe polysaccharide contained 1 →4 glycosidic bond and was methylatedpolysaccharide. The molecular weight of aloe polysaccharide was 112 381 u. Results of activity test showed that aloe polysaccharide and its derivatives had excellent antioxidant activity, which was similar to that of positive control VC. Structure-activity relationship study showed that phosphorylated aloe polysaccharides had the best antioxidant activity compared with the aloe polysaccharides and the other two derivatives in vitro. This study provides a theoretical basis for further study of aloe polysaccharides structure and development of functional food and medicine.