Structure-activity Relationships Of Carrageenan Sulfated Derivatives On Anticoagulative Activity And Cytotoxicity

Objective:Takenκ-carrageenan as the center structure, carrageenan sulfated derivatives with different structures were prepared to study the effect of sugar unit structure, the degree and position of sulfated substitution and the molecular weights on anticoagulant activity and cytotoxicity of carrageenan, aimed to investigate the structure-activity relationships between different carrageenan derivatives systematically. Methods:Low molecular weightκ-carrageenan and its oligosaccharides,κ-carrageenan sulfated and desulfated derivatives were prepared. The anticoagulant potency ofκ-carrageenan and its derivatives were detected according to rabbit whole blood method, APTT, PT and spectrophotometric method. The cytotoxic effect ofκ-carrageenan and its derivatives on human umbilical vein endothelial cells (HUVEC) were examined by MTT method. Results:Different anticoagulant assay indicated thatλ-carrageenan has the most potent anticoagulant activity whereas its potency is 6% of heparin. The degree of substitution had the greatest influence on anticoagulant activity, and it fitted a linear relation to the number of the substitute group. Sulfated groups on C-6 ofβ-(1→3)-D-Gal displayed the strongest anticoagulant activity. APTT and PT experiments exhibited that the anticoagulant approach of carrageenan was endogenous. MTT assay showed that the survival rate of HUVEC varied distinctly with the molecular weight ofκ-carrageenan. Theκ-carrageenan oligosaccharides had no inhibition on cell survival. The degree of the sulfated substitution showed strong effect on cell inhibiting rates. When substituted on the same sugar ring,κ-carrageenan sulfated derivative with two sulfated groups had the strongest inhibition on HUVEC. Meanwhile, the substitutional position also had influence on HUVEC inhibiting rate to some degree, and it was supposed that the order of the cytotoxicity of the substitutional position was C-6>C-4>C-2. Conclusion:The structure-activity relationships based on the effect of different molecular weight, substitutional degree and position of carrageenan on its anticoagulant activity and cell proliferation were revealed.