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Purpose: The aim of this work was to study the effect of the synthetic antifibrinolytics: ε-aminocaproic acid (EACA), tranexamic acid (AMCHA) and ε-aminocaproyl-S-benzyl-L-cysteine (H-EACA-S-Bzl-L-Cys-OH) on the fibrinolytic activity of saliva in order to obtain new data on the activity of saliva tissue plasminogen activator (t-PA)., Material and Methods: Saliva samples were obtained from healthy volunteers. Saliva, precipitate and supernatant were tested 1hr, 4 hrs and 6hrs after collection. The effect of the synthetic antifibrinolytics was examined with the use of the clot lysis time determination., Results: All examined compounds inhibited the fibrinolytic activity of saliva 1hr after collection. H-EACA-S-Bzl-L-Cys-OH was the most active inhibitor. After 6 hours in room temperature only this compound showed a certain possibility to prolong the clot lysis time., Conclusions: The obtained results may indicate the possibility of the difference in specificity between the activities of t-PA of saliva and recombinant tissue plasminogen activator activities. It may explain the unexpected high inhibitory activity of H-EACA-S-Bzl-L-Cys-OH in our study.

Purpose: The aim of the study is the examination of effects of dipeptides containing S-hexyl-L-cysteine and glycine, on the prothrombin activation and the thrombin clotting time determined in the presence of heparin., Material and Methods: The activation of prothrombin was determined with the use of the thromboplastin test, the recalcification and partial thromboplastin with kaolin tests. The thrombin clotting time determined in the presence of heparin was evaluated with the use of the heparin-thrombin test., Results: The investigated derivatives slightly inhibited the prothrombin activation. The unsubstituted derivatives and dipeptides with a free amino or carboxyl group significantly enhanced the clotting time determined in the presence of heparin at concentration 20 mM. S-Hexyl-L-cysteinylglycine (H-(S-hexyl)-L-Cys-Gly-OH) was the most active compound., Conclusions: The obtained results indicate that some dipeptide derivatives of S-hexyl-L-cysteine apart from the earlier observed possibility to prolong the thrombin clotting time, can also prolong the clotting time determined in the presence of heparin.

A series of tripeptide methylketones with C-terminal lysine was obtained via Dakin-West method and tested for their antiplasmin activity with the use of antifibrinolytic and antiamidolytic tests. The tripeptide methylketones has been found to inhibit plasmin, however with much lower potency than respective aldehydes.