THE INHIBITION OF BLOOD CLOTTING BY PHOSPHATE ESTERS OF VITAMINS K AND E

Abstract

Vitamin K1phosphate was incubated with thromboplastin and the mixture used for the determination of the one-stage prothrombin time of human plasma. No change in thromboplastic activity was observed. The thrombin times of an artificial clotting system composed of a 1% fibrinogen solution were prolonged following incubation with vitamin K1phosphate. The inhibitory activity of vitamin K1phosphate, alpha-tocopherol phosphate, and menadiol sodium diphosphate on the one-stage prothrombin and the clotting times of rat and human plasmas was followed. Vitamin K1phosphate and alpha-tocopherol phosphate showed greatest activity while Synkavite showed only slight activity. At low concentrations of the phosphate derivatives the inhibition was found to be a linear function of the log of the prothrombin and clotting time. It is suggested that the phosphorylated derivatives inhibit the clotting process by interfering with the polymerization of fibrin.