Sulfated polysaccharide purified from Ecklonia cava accelerates antithrombin III-mediated plasma proteinase inhibition

Surface plasmon resonance is an important technique for studying molecular interactions and was used to investigate the molecular interaction of anticoagulant sulfated polysaccharides purified from an enzymatic hydrolysate of the brown alga Ecklonia cava (ECA) with blood coagulation factors. In a direct binding assay, binding affinity between ECA/antithrombin III (ATIII) and activated blood coagulation factors was in the order: factor VIIa (FVIIa) > factor Xa (FXa) > thrombin (FIIa); kinetic analysis determined K(D) values of ECA for FVIIa, FXa, and FIIa of 15.1, 45.0 and 65.0 nM, respectively. Therefore, ECA strongly and selectively (FVII, FX, and FII) enhanced ATIII-mediated coagulation factor inhibition in both the extrinsic and common coagulation pathways. This may contribute to its high anticoagulant activity in vitro. The low cytotoxicity of ECA to venous endothelial cell line (ECV-304) also expands its value in future in vivo studies. However, to utilize it as a model for novel anticoagulant agents, its possible interference with other anticoagulant mechanisms must be addressed.