Junichi Takahara

Anticoagulant activity of enzymatically synthesized amylose derivatives containing carboxy or sulfonate groups

Heparin is an extracellular matrix polysaccharide. It is widely employed as an anticoagulant and can be used to form an anticoagulant surface on various medical devices such as renal dialysis devices to prevent thrombosis. However, heparin may cause hemorrhage and thrombocytopenia. Moreover, commercially available heparin may be contaminated with viruses and allergens of animal origin, as it is derived mainly from porcine or bovine tissue. To avoid these problems, we prepared succinated and sulfonated enzymatically synthesized amylose (SucESA and SulfESA, respectively) and assessed their anticoagulant activity. SucESA and SulfESA inhibited factor Xa activity in normal human plasma to an equal extent. However, SucESA strongly inhibited thrombin activity, whereas SulfESA only inhibited it slightly. These results suggest that SucESA inhibits the activities of both factor Xa (or its upstream coagulation factors) and thrombin and that SulfESA inhibits only factor Xa activity (or that of its upstream coagulation factors). SucESA and SulfESA with a high degree of substitution strongly inhibited factor Xa and thrombin activity compared with those of the derivatives with a low degree of substitution, even when present in high concentrations. This suggests that the density of the anion group determines the degree of inhibition of factor Xa and thrombin activity. SucESA, which has a high molecular weight, inhibited thrombin activity to a greater degree than low molecular weight SucESA. Because SucESA and SulfESA inhibited both purified factor Xa and thrombin irrespective of the presence of antithrombin, it is suggested that SucESA and SulfESA inhibit via direct action with both enzymes.