Studies On The Physicochemical Properties, Separation And Bioactivities Of Alginate Oligosaccharides

Alginate is a polysaccharide extracted from kelp or sargassum which belongs to the brown algas group. Alginate posess both good biodegradability and biocompatibility properties. Alginate oligosaccharide is a marine acidic oligosaceharides with good anti-virual, anti-tumor and anti-inflammation activities. Therefore, alginate oligosaccharide is of great potential pharmaceutical usege. This thesis studied physicochemical properties, separation and bioactivities of alginate oligosaccharide derived from enzymatic digestion of alginate polysaccharide.1. MS and TLC Analysis of Alginate OligosaccharidesThe MS and TLC analysis shows that the alginate oligosaccharides mixtures is made up of oligouronic acid (polysaccharide may be contained). Every oligosaccharide molecule contains a double bond.2. The Physicochemical Properties Analysis of Alginate OligosaccharidesThe physicochemical properties of alginate oligosaccharides were determined by HPLC, GC, and UV spectrometer. The UV spectrum shows that there is no protein in this aforementioned oligosaccharides. The total sugar content and uronic acid content are 74.89% and 74.36% respectively. Gas chromatography analysis showed that the polysaccharide was composed of mannuronic acid and guluronic acid. High-performance gel-permeation chromatography analysis showed that the polysaccharide in the sample molecular mass is approximately 1.7×10~4Da.3. Separation and Preparation of the OligosaccharidesSilica gel column chromatography were applied to separate alginate oligosaccharides, the oligosaccharides was partially separated (eluant: n-butanol/ methanoic acid/ water=4/6/l). Under the same conditions, we conducted a second separation. By MS analysis, the oligosaccharides (degree of polymerization is 2-5) has been separated. The disaccharides and the trisaccharides are of high purity.4. Bioactivities Assaying of Alginate Oligosaccharides The bacteriostatic activity of crude alginate oligosaccharides and the oligosaccharides with a low degree of polymerization(DP2-5) were also investigated. The results showed that all the samples inhibit Escherichia coli proliferation. The minimum inhibitory concentration (MIC) of the alginate oligosaccharides is 0.563 mg/mL. In addition, we studied the anti-tumor (human liver cell SMMC-7721) activity of crude alginate oligosaccharides,oligosaccharides (DP2-9),polysaccharide(more than DP9). The results indicated that only the oligosaccharides(DP2-9) demonstrates anti-tumor activity.