Free Radical Degradation Of Seaweed Sulfated Polysaccharides

Three fractions (LAS-1, LAS-2, LAS-3) were obtained from Laminaria Japonica by enzymolysis, isolation and purification. Their molecular weight is about 2690KD. Because of the biological functions of LAS closely correlate with the molecular weight, when the LAS has large molecular weight, the study on the physic-chemical characterization and physiological functions is limited. So it is an urgent question to optinize the Laminaria polysaccharide sulfate products and to find a proper way which can be used to degrade polysaccharide. Now there are many ways to degrade polysaccharide, such as classical enzymolysis and acidolysis, which are effectual to the same polysaccharide, but not to Laminaria polysaccharide sulphate. Many kinds of sugar are composed of LAS and their link sites are diverse, and the scope of the molecular weight by common degradation ways is wide. Recent research indicated that the free radical played an important role in many kinds of degradation ways, such as enzymolysis, oxidation degradation and ultrasonic degradation. Free radical degradation is a good way studied by experiment.In the course of the free radical degradation, we adopted two system: Harber-Weiss system and Fenton system. In Harber-Weiss system, it is H₂O₂+VC that have a degradation effect on the polysaccharide together, not a single one. When the polysaccharide was degraded, its colour became light and molecular weight reduced. The band on the electrophoresis picture became concentrated, but the band of the non-degradation polysaccharide was wide. The degradation degree of the polysaccharide was correlation with the environment temperature and the concentration of the substrate. The degradation degree became greater with the rising of the temperature (15-40℃). And with the increasing of the concentration of the substrate, the extent of the degradation also got bigger. But if the concentration of the H₂O₂ and VC increased continually, the degradation extent could not improve.