Synthesis and Biological Activity of N-Sulfonyltripeptides with C-Terminal Arginine as Potential Serine Proteases Inhibitors.

Tripeptides of the general X-SO2-d-Ser-AA-Arg-CO-Y formula, where X = α-tolyl, p-tolyl, 2,4,6-triisopropylphenyl; AA = alanine, glycine, norvaline and Y = OH, NH-(CH2)5NH2 were obtained and tested for their effect on the amidolytic activities of urokinase, thrombin, trypsin, plasmin, t-PA and kallikrein. The most active compound towards urokinase was PhCH2SO2-d-Ser-Gly-Arg-OH with Ki value 5.4 µM and the most active compound toward thrombin was PhCH2SO2-d-Ser-NVa-Arg-OH with Ki value 0.82 µM. The peptides were nontoxic against porcine erythrocytes in vitro. PhCH2SO2-d-Ser-Gly-Arg-OH showed cytotoxic effect against DLD cell lines with IC50 values of 5 µM. For the highly selective determination of the interaction of some of the synthesised acids of tripeptides with urokinase and plasmin the Surface Plasmon Resonance Imaging sensor has been applied. These compounds bind to urokinase and plasmin in 0.05 mM concentration.

Effect of short peptides containing lysine and epsilon-aminocaproic acid on fibrinolytic activity of plasmin and topoisomerase II action on supercoiled DNA.

Effects of eight short peptides containing lysine and epsilon-aminocaproic acid (EACA) on prolongation of the clot lysis time, as well as hemolytic and antibacterial activities were investigated. Interaction with plasmids pBR322 and pUC19 with the use of ethidium bromide assay and determination of influence on the activity of topoisomerase I and II were also tested. Examined compounds inhibited fibrinolytic activity of plasmin and five of them were more active than EACA. Amides of dipeptides were most active antifibrinolytics (IC50 < 0.2 mM). According to the obtained data, the significant inhibition of fibrinolytic activity of plasmin was not associated with hemolytic effects. Examined compounds did not show antibacterial activity (MIC > 512 mg/L). DNA binding effects determined with the use of ethidium bromide were weak for all peptides and similar to those observed with EACA. Six compounds inhibited topoisomerase II action on supercoiled DNA.

Tripeptides with non-code amino acids as potential serine proteases inhibitors.

Eight peptides of the general H-D-Ser-AA-Arg-OH formula, where AA = phenylglycine, phenylalanine, homophenylalanine, cyclohexylglycine, cyclohexylalanine, homocyclohexylalanine, α-methylphenylalanine and 1-aminocyclohexyl carboxylic acid were obtained and tested for their effect on the amidolytic activities of urokinase, thrombin, trypsin, plasmin, t-PA and kallikrein. We tested the hemolytic activity of the peptides against porcine erythrocytes and the antitumor activity against the human breast cancer cells, standard MCF-7 and estrogen-independent MDA-MB-231. The most active compounds were H-D-Ser-Chg-Arg-OH towards thrombin and H-D-Ser-Phg-Arg-OH towards plasmin with K(i) value 5.02 µM and 5.7 µM, respectively.

Effect of epsilon-aminocaproylamino acids on fibrin formation.

Effect of three epsilon-aminocaproylamino acids with significant antifibrinolytic activity on polymerization of fibrin monomer, clot retraction, fibrin structure, prothrombin consumption and thrombin activity was examined. epsilon-Aminocaproyl-L-norleucine and epsilon-aminocaproyl-L-leucine were weak inhibitors of thrombin activity and epsilon-aminocaproyl-L-norleucine slightly inhibited polymerization of fibrin monomers.