Study On The Activities And Preparation Of Starch Sulfates And Alginate Sulfates

Sulfated polysaccharide is a kind of natural or semi-synthetic acid polysaccharide with sulfated group in the saccharide hydroxyls, which possesses various biological properties such as antiviral, antitumor, anticoagulant, anti-oxidative, antiulcer, immune-enhancing effects and so on, and therefore it has been one of the research hotspots for a long time.In order to improve the biological properties of polysaccharides, molecular modification and structural improvement of polysaccharides become of significant importance. Sulfated modification is one of the important research areas. The methods to preparing sulfated polysaccharides mainly includes in the use of chlorosulfonic acid, sulfur trioxide, sulfuric acid, sulfamic acid and sodium bisulfite, which exist shortcomings and limitations to some extent, such as poisonous organic solvents or cancerogenic reagents, which may result in poor security,environmental pollution and high cost. Accordingly it will greatly accelerate the further application of sulfated polysaccharides to develop some low-cost and environmentally friendly production technology.This article focused on the preparation technology study of starch sulfates and sodium alginate sulfates by the use of two widespread natural polysaccharides-potato starch and sodium alginate as the raw materials. And then the anticoagulant and pepsin-inhibition activities were studied. The main studies of this dissertation are shown as follows:(1) Synthesis and optimization of starch sulfates and sodium alginate sulfatesSulfuric acid with some inert process can be directly added into polysaccharides to prepare polysaccharide sulfates. This method is of easy operation and low cost, and inert sulfuric acid can solve the problems of extreme hydrolysis or degradation and easy carbonization by the direct use of sulfuric acid. Moreover it avoids the use of organic solvents and is friendly to the environment, so it is potential to put into use in industrial production.This paper successfully synthesized starch sulfates and sodium alginate sulfates. The factors that could affect the degree of substitution(DS) of the two polysaccharide sulfates were investigated in detail, and the optimal reaction conditions were found. The results showed that the reaction ratio, reaction time and reaction temperature had an effect on the DS. The DS increased with the increasing dosage of inert sulfuric acid and the reaction time within some limits, but decreased with the increasing reaction temperature. The optimal reaction condition of starch sulfates was as follow:nH2SO4/nSt3.6, dehydration rate10.6%, reaction time3h, reaction temperature0℃, and a maximum DS of1.286was obtained. While the optimal reaction condition of sodium alginate sulfates was nH2SO4/nsA6, reaction time4h, reaction temperature5℃, and a maximum DS of1.372was obtained.(2) The anticoagulation of starch sulfates and sodium alginate sulfatesThe in-vitro anticoagulation tests showed that both starch sulfates and sodium alginate sulfates significantly prolonged tAPTT, slightly prolonged tPT, but couldn’t prolong tTT, which indicated that the two polysaccharide sulfates revealed good anticoagulant effects both in intrinsic and extrinsic coagulation pathway. The anticoagulant effects increased with the increasing concentration of the two polysaccharide sulfates, while the relationship of the DS and anticoagulant effects was not clear.(3) The pepsin inhibitory activities of starch sulfatesIn this paper, the effect of starch sulfates on pepsin proteolysis in vitro was determined by the ultraviolet spectrophotometry using Bovine hemoglobin as substrate for pepsin digestion. The results showed that the activity of pepsin in the presence of starch sulfates was lower than that of pepsin without starch sulfates, which indicated that starch sulfates had an inhibitory effect on pepsin proteolysis. The inhibition ratio increased with the increasing concentration of starch sulfates, while the relationship of the DS and inhibition ratio was not clear. At last a maximum inhibition ratio of57.44%was obtained.The ultraviolet absorption spectrum difference displayed that pepsin appeared two absorption peaks at223nm and274nm after starch sulfates was added to pepsin, and the absorption value increased with the increasing concentration of starch sulfates. It demonstrated that the spatial structure of pepsin changed after starch sulfates acted on pepsin.