The Preparation, Characterization And Bioactivity Analysis Of The Nonderived, Water-soluble Chitin

In this paper, a new technics of preparing nonderived, low degree of deacetylation, water-soluble chitin and an assay to define the molecular weight and degree of deacetylation have been investigated. The structureactivity was studied by comparing the antibacteria, promot-coagulation and antitumour activities of water-soluble chitin with different deacetylation degree and molecular weight.The technics conditions of producing low degree of deacetylation, water-soluble chitin by nonderived assay were investigated in detail. Three perfect producing methods with high yield to obtain low degree of deacetylation chitin have been built by optimizing the swelling time, final concentration of NaOH and alkali treatment time. The optimized technics can greatly increase the yield and shorten the basification time by 3 folds.The structural difference of a series of water-soluble chitin with distinct degree of deacetylation was characterized by IR, 'H-NMR and CD spectra. There deduce diversities in their crystallinity and spatial structure through the chromatograms, while the most important diversity was the distinct of the inter-and intra- hydrogen bond.The antibacteria investigation showed that water-soluble chitin had stronger bactericidal effects with gram-positive bacteria than gram-negative bacteria. Both the degree of deacetylation and the molecular weight remarkably influence their antibacterial activities. Moreover distinct effects were observed to different kinds of bacteria and high molecular weight chitin showed stronger bactericidal effects of oligomers.The promot-coagulation results indicated that the water-soluble chitin had relatively good promot-coagulation activity, furthermore the promot-coagulation activity of water-soluble chitin with lower degree of deacetylation was much stronger than that of those with higher degree of deacetylation. The mechanism study showed that the water-soluble chitin achieved their promot-coagulation activity mainly by affecting the extrinsic pathway of coagulation and the activities of the thrombins. Furthermore the water-soluble chitin also promoted the conglomeration of blood platelets and erythrocytes.The antitumour study manifested that the water soluble chitin had good antitumour activity. The flow cytometry analysis showed that water-soluble chitin could markedly inhibit the proliferation and induce the apoptosis of A549.