Acetylation Of Monosaccharide And Biochemical Studies Of Glycoprotein From Chinese Soft-shell Turtle

The per-O-acetylation of monosaccharides is an important and frequently used transformation in organic synthesis. Acetic anhydride is generally used as the acetylating reagent with a variety of catalysts. The catalyst most often employed is pyridine which can also serves as a solvent despite its known toxicity and unpleasant odor. Compared with acetic anhydride, vinyl acetate is less toxic and easier handled. The byproduct of the acetylation using vinyl acetate is acetaldehyde, which is gaseous at 25⁰C. With all these features, we were encouraged to expand studies on the base-catalyzed sugar per-O-acetylation reactions. We’ve worked out a facile and novel approach for per-O-acetylation of monosaccharides with vinyl acetate using Na₃PO₄ as the catalyst and water as the solvent. The reaction is operationally simple and environment friendly with short reaction time and easy workup. These features, combined with the recyclable catalyst, make this method an attractive alternative to existing methodologies for the acetylation of monosaccharide.AbPS is a well-known polysaccharide isolated from a traditional Chinese herbal medicine- achyrnthes bidentata, with extensive immunomodulatory activities. For expansion of its application, a series of derivatives are synthesized through sulfation, phosphorylation, carboxymethylation and hydroxyethylation. They exhibit the improved, even new biological activities, compared with the parent polysaccharide. But there is no report dealing with its acetylation. So we intend to extend its application and obtain new acetylated derivatives. Applying this new method to the acetylation of achyrnthes bidentata polysaccharide （AbPS）, partially acetylated product was successfully obtained high degree of substitution （D.S.=1.9）. We also used classical method for this purpose by using acetic anhydride and pyridine. Fully acetylated product was obtained through this way. Tests on biological activity for both the products showed that only the partially acetylated one had enhanced bioactivity.Research on glycoconjugate isolated from natural product is another hot topic for carbohydrate researchers. Trionyx sinesis is a famous traditional Chinese medicine. Due to its rich nutritional value and high medicinal value, it has attracted the attentions of people of all ages. There is no systematic report of the research conducting on the blood of Trionyx sinesis up to now, and usually we treat the blood as waste disposal. We plan to carry out research on the blood of Trionyx sinesis. With modern biotechnology and membrane separation technology, we’ve isolated several crude glycoconjugates from the blood, which possess physiological activity. And then, we selected one component with highest content and purified it. Next, we will take on detailed and thorough study on it, such as component analysis, molecular weight, carbohydrate content as well as its structure.