The Research On Low Molecular Weight κ-carrageenan Modified By Salicylic Acid Drugs And Its Biological Activity Tests

In recent years, the chemical modification of marine polysaccharides, which lead to preparation of derivatives with high biological activities and low toxicity, has attracted more and more attention. Carrageenan is a collective term for a group of sulfated polysaccharides extracted from marine red algae and it was widely studied because of its biological activities such as anti-virus, anti-coagulant, anti-tumor and so on. Molecule weight of the natural carrageenans is so large that it is difficult to penetrate biofilm. So the application of carrageenans to clinical is restricted. Depolymerization and O-acylation of carrageenans are favor of improving their bioactivity. Two kinds of derivatives of Low-molecular-weight (LMW) carrageenans have been successfully synthesized and their fine structure has been characterized by UV, FT-IR, 1H NMR and 13C NMR spectrum. Bioactivities of the products were preliminarily investigated. The main contents were summarized as follows.First, O-salicyloyl derivative of low molecular weightκ-carrageenan (SKC) was synthesized. The synthesis of SKC was performed by using of salicylic acid, tetrabutylammonium salt of LMWκ-carrageenan with N, N-dimethylformamide (DMF) as solvent in the presence of N,N'-Dicyclohexylcarbodiimide (DCC) as catalyst at 30℃. The influence of temperature and time of reaction on the degree of acylation of the product were investigated. The fine structure of SKC was characterized by means of 1H NMR, 13C NMR, IR and UV. The results showed that salicylic acid was reacted with the Hydroxyl groups on C-6 of 3-linkedβ-D-galactopyranosyl-4-sulfate unit (G4S) ofκ-carrageenan and formed the SKC.In addition, methyl salicylate derivatives of low molecular weightκ-carrageenan were synthesized . Succinyl methyl salicylate was performed by use of succinic acid, methyl salicylate and pyridine as solvent and catalyst at 100℃. Furthermore, succinyl methyl salicylate-g-low molecular weightκ-carrageenan (SMKC) was successfully synthesized using succinyl methyl salicylate and low molecular weightκ-carrageenan as reactants. The structure of the products were confirmed by UV, FT-IR,1H NMR and 13C NMR spectrum.At last, Studies on antioxidant actives in vitro of SKC and SMKC was performed and the antioxidant property can be improved by theκ-carrageenan, which had been modified by salicylic acid and methyl salicylate.