Influence of dipeptide derivatives of S-substituted cysteines on the time of fibrinolysis

Amino acids containing sulphur, dipeptide derivatives of methionine and S-substituted derivatives of cysteine are potent antifibrinolytic agents. The structural moiety of the substances responsible for the effect on the clot formation is not known. Present study was undertaken in order to evaluate the effect of some analogues of dipeptides containing S-substituted derivatives of cysteine with the formula A-Cys(S-X)-Y (where A-amino acid, X-benzyl, butyl, hexyl, nonyl and Y-OH or OMe) on clot dissolution under the antifibrinolytic test conditions. It has been found that dipeptide derivatives of S-substituted cysteine (except benzyl derivative) at low concentration evoke antifibrynolytic activity, while at high concentration they prevent clot formation. The results suggest that antifibrinolytic activity of tested compounds at low concentration may be due to the formation of antifibrinolitycally active conformation, while high concentration overcome the effect.