ORIGINAL RESEARCH Thrombin inhibitory activity of some polyphenolic compounds

Abstract Thrombin, also known as an active plasma coagulation factor II, belongs to the family of serine pro-teases and plays a crucial role in blood coagulation process. The process of thrombin generation is the central event of the hemostatic process and regulates blood coagulant activity. For this reason, thrombin inhibition is key to successful novel antithrombotic pharmacotherapy. The aim of our present study was to examine the effects of the well-known polyphenolic compounds on the activity of throm-bin, by characterization of its interaction with selected polyphenols using different biochemical methods and biosensor BIAcore analyses. Only six compounds, cyani-din, quercetin, silybin, cyanin, (?)-catechin and (-)-epi-catechin, of all examined in this study polyphenols caused the inhibition of thrombin amidolytic activity. But only three of the six compounds (cyanidin, quercetin and sily-bin) changed thrombin proteolytic activity. BIAcore anal-yses demonstrated that cyanidin and quercetin caused a strong response in the interaction with immobilized thrombin, while cyanin and (-)-epicatechin induced a low response. Lineweaver–Burk curves show that used poly-phenol aglycones act as competitive thrombin inhibitors. Our results suggest that polyphenolic compounds might be potential structural bases and source to find and project nature-based, safe, orally bioavailable direct thrombin inhibitors