Separation And Purification Of Polysaccharides From Porphyridium Cruenium And Its Properties

The marine microalga Porphyridium cruentum can synthesize and secrete the sulfated polysaccharides when the cell grows to its steady period. The extraction of the polysaccharide is an important process for activity research. In order to optimize the extraction craft of polysaccharide, the orthogonal experiment and regression analysis were used to investigate the effect factors. Besides, different crafts of deproteinization were comparied. On the basis of separation and purification of polysaccharides from P. cruentum (PSP), the physicochemical properties and structure of PSP were determined by chemical methods and spectrum analysis. All the results were summarized as follows:(1) The optimum extracting condition was ratio of material and water 1:4, temperature 84℃, extracting time 2.1h and pH 8.0. Under the optimal extracting condition, the maximum yield of PSP was 4.21mg/L. The results of removing protein showed that the method of TCA had the best effect, the next was the method of enzyme, and the last was method of Sevag.(2) The uniform polysaccharides were obtained by DE52 anion-exchange chromatography and Sephacryl S-400 gel filtration chromatography. The purity of PSP was determined by HPGPC and paper chromatography, and the molecular weight of PSP was 2.61×106 Da.(3) Analysis results of physiochemical properties showed that the total sugar content of PSP was 92.6%, the aldonic acid content was 7.8% and the sulfuric content was 11.4%. The UV analysis showed there was no free protein and nucleic acid in PSP. The PSP had favourable rheological property, whose water-solution showed high viscosity in low concentration. The water-solution of PSP had shearing dilution effect,and showed typical non-Newtonian fluid property. Besides, the rheological property of the water-solution of PSP was stable, which could not be affected by environmental factors such as temperature, pH, salinity et al.(4) The IR spectrum showed the characteristic absorption peak of polysaccharide, which indicated that PSP was the sulfated polysaccharide, and included theβ-D-pyranose. GC analysis showed that PSP was a heteropolysaccharide, which consisted of xylose, glucose and galactose, and their moceluar ratio was 2.96:1.25:3.06.