Background: Modern views about hemostasis and thrombosis and the experience of using antithrombotic agents (anticoagulants, thrombolytic and antiplatelet agents) suggest that the development of synthetic low molecular weight direct thrombin inhibitors is promising because this enzyme is the key in the blood coagulation system, and its increased activity is capable to lead to thrombosis. IEM-2280 (N-[N´-tret-butyloxycarbonyl-4-amino-3-phenyl-butyryl]arginine hydrochloride) synthesized in the Department of Neuropharmacology named after S.V. Anichkov (Institute of Experimental Medicine) is one of these compounds.

Aims: The aim of this work was to investigate the ability of IEM-2280 to provide antithrombotic effect.

Methods: The enzymatic activity of purified thrombin was evaluated by cleavage of a chromogenic substrate H-D-phenylalanine-L-pipecolyl-L-arginine-4-nitroanilide dihydrochloride (S-2238) with the formation of p-nitroaniline and also by coagulation of fibrinogen. The kinetics of the reaction was studied by the photometric method at λ=405 nm. Formation of thrombin-induced platelets aggregates was analyzed by using turbidometric aggregometry by detecting changes in the light transmission of cell suspensions at λ=540 nm.

Results: Studies have shown that IEM-2280 in a concentration-dependent manner reduced the enzymatic activity of thrombin determined by the ability of the enzyme to cleave the chromogenic substrate. The concentration of half-maximal inhibition (IC₅₀) was 1.7±0.3 µM. Coagulation of fibrinogen completely blocked by 2 µM IEM-2280. It was found that IEM-2280 also effectively inhibited thrombin-induced (40 ng/ml) platelet aggregation, IC₅₀ was 2.8±0.6 µM.

Conclusions: It was found that IEM-2280 is able to inhibit the enzymatic activity not only purified thrombin, but also thrombin-induced platelet aggregation. Since arginine is a precursor to NO, it is possible that the effect of IEM-2280 on platelets may be associated including with inhibition of platelet aggregation by NO.We can conclude that the IEM-2280 is promising compound to create on its basis of drugs with a pronounced antithrombotic action. This study supported by MD-1901.2020.4 grant.

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ISTH Congress Abstracts - https://abstracts.isth.org/abstract/study-of-a-new-synthetic-thrombin-inhibitor-iem-2280/