Studies On Separation, Preparation And Antioxidant Activity Assay Of Active Oligo-uronic Acids From Algiante Acids

Alginate Acid is one of the natural acidic polysaccharides. It is widely used in areas of Food and Pharmacy. In this paper, we firstly obtained Poly Mannuronic acid and Poly Guluronic acid by partial acid hydrolysis and fractional separation. then, Prepared homogeneous oligo-mannuronic acids and oligo-guluronic acids. The separation and preparation of these oligosaccharides monomers were achieved by strong anion-exchange chromatography. Finally, we preliminarily explored bioactivities of oligo-mannuronic acids and oligo-guluronic acids. The results were summarized as fellows:1. Several physicochemical properties of Alginate acidGas chromatography(GC) analysis showed that Alginate acid is consisted of Mannuronic acid(M) and Guluronic acid (G)with the ratio of 3.9:1; Phenol-sulphuric acid analysis indicated that the total sugar content of Alginate acid was 83%; The Uronic acid content of Alginate acid was 83.3% detected by Carbazole-sulphuric acid method; High-performance gel-permeation chromatography (HPGPC)analysis indicated that the molecular weight of Alginate acid is 9.5×104Da.2. The preparation of Alginate oligosaccharides by enezyme degaradationPoly Mannuronic acid and Poly Guluronic acid were respectively obtained by partial acid hydrolysis and Fractional separation. then Poly Mannuronic acid and Poly Guluronic acid were digested with a commercially available Alginate lyase from Flavobacterium sp. to obtain a mixture of Oligo-ManA(Dp2-11) and Oligo-GulA(Dp2-11) under their own optimum zymolatic conditions.3. The separation and ESI-MS analysis of the two kinds of oligoasccharidesOligo-ManA (Dp2-11) and Oligo-GulA (Dp2-11) respectively was separated by strong anion-exchange chromatography to obtain Oligo-ManA and Oligo-GulA monomers with the help of gradient elution apparatus. the results of ESI-MS analysis indicated that Oligo-ManA monomers (Dp2-4) and Oligo-GulA monomers(Dp2-5) could be well separated and pepared with this method. By the MS2 analysisy of Tetra-ManA and Tetra-GulA labled with 1-Phenyl-3-methyl-5-pyrazolone (PMP), m/z 797.17 was found as the different ion fragmentation between each other.4. Biological activities assay of Oligo-Mannuronic acids and Oligo-Guluronic acids we examined the scavenging activity of superoxide radicals (02·-) with the help of the self-oxidation of 1,2,3-phentriol assay. In addition, Fenton-reaction assay is used to study the scavenging activity of hydroxyl radicals (·OH). the results implied that oligo-mannuronic acids and oligo-guluronic acids are both able to scavenge O2·-and·OH. With the concentration of samples increased, the power of scavenging became stronger. Compared with oligo-Mannuronic acids, oligo-Guluronic acids had stronger scavenging ability of O2·-, while weaker scavenging power of·OH.