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KTTKS is a matrikine that originates from the proteolytic hydrolysis of collagen. This peptide stimulates ECM production and types I and III collagen expression in vitro. A more stable form of KTTKS is pal-KTTKS, known as Matrixyl&reg, or palmitoyl pentapeptide-3. A series of novel pentapeptides, analogues of KTTKS with the general formula X-KTTKS-OH(NH2), where X = acetyl, lipoyl, palmitoyl residues, was designed and synthesized. Their effect on amidolytic activity of urokinase, thrombin, trypsin, plasmin, t-PA, and kallikrein were tested. Cytotoxic tests on fibroblasts, as well as collagen and DNA biosynthesis tests for selected peptides, were also carried out. The test results showed that the most active plasmin inhibitors were palmitoyl peptides, whether in acid or amide form. No biological effects of lysine modification to arginine in the synthesized peptides were found. None of the synthesized peptides was not cytotoxic on fibroblasts, and three of them showed cell growth. These three compounds showed no concentration-activity relationship in the collagen and DNA biosynthesis assays.

Fifteen new peptide derivatives of ɛ-aminocaproic acid (EACA) containing the known fragment –Ala–Phe–Lys– with an affinity for plasmin were synthesised in the present study. The synthesis was carried out a solid phase. The following compounds were synthesised: H–Phe–Lys–EACA–X, H–d-Ala–Phe–Lys–EACA–X, H–Ala–Phe–Lys–EACA–X, H–d-Ala–Phe–EACA–X and H–Ala–Phe–EACA–X, where X = OH, NH2 and NH–(CH2)5–NH2. All peptides, except for those containing the sequence H–Ala–Phe–EACA–X, displayed higher inhibitory activity against plasmin than EACA. The most active and selective inhibitor of plasmin was the compound H–d-Ala–Phe–Lys–EACA–NH2 which inhibited the amidolytic activity of plasmin (IC50 = 0.02 mM), with the antifibrinolytic activity weaker than EACA. The resulting peptides did not affect the viability of fibroblast cells, colon cancer cell line DLD-1, breast MCF-7 and MDA-MB-231 cell lines.

The biological evaluation of carbocyclic minor groove binders 1-6 is described. The cytotoxicity of the obtained compounds was tested on MDA-MB-231 breast cancer cells. The mechanism of action of compounds 1-6 was studied employing the topoisomerase I/II inhibition assay and ethidium displacement assay using pBR322. Determination of association constants was done using calf thymus DNA, T4 coliphage DNA, poly(dA-dT)(2), and poly(dG-dC)(2). The effect of compounds 1-6 on the amidolytic activity of plasmin, trypsin, thrombin, and urokinase was also examined.

Eight peptides of the general formula X-d-Ser-AA-Arg-Y where X = H, Ac; AA = Ala, Gly and Y = OH, NH2 were obtained and tested for their effect on the amidolytic activities of urokinase, thrombin, plasmin, and trypsin.

epsilon-Aminocaproic acid (EACA) is a synthetic low molecular drug with antifibrinolytic activity. However, treatment with this drug can be incidentally associated with an increased thrombotic tendency. The aim of the present work was to test synthetic EACA derivatives for their antiplatelet activities. We investigated the effect of three EACA derivatives with antifibrinolytic activity: I. epsilon-aminocaproyl-L-leucine hydrochloride (HCl*H-EACA-L-Leu-OH), II. epsilon-aminocaproyl-L-(S-benzyl)-cysteine hydrochloride (HCl*H-EACA-L-Cys(S-Bzl)-OH) and III. epsilon-aminocaproyl-L-norleucine (H-EACA-L-Nle-OH) on platelet responses (aggregation and adhesion) and on their integrity. It was found that: 1. as judged by LDH release test, none of the tested compounds, up to 20 mM, was toxic to platelets, 2. in comparison with EACA, all the synthetic derivatives inhibited much stronger the ADP- and collagen-induced aggregation of platelets suspended in plasma (platelet rich plasma) and aggregation of these cells in whole blood, 3. EACA and its derivatives exerted a similar inhibitory effect on the thrombin-induced adhesion of platelets to fibrinogen-coated surfaces. Since platelet activation and blood coagulation are tightly associated processes, the antiplatelet properties of EACA derivatives are expected to indicate reduced thrombotic properties of these derivatives compared to EACA.

Purpose The aim of this work was to study the effect of the synthetic antifibrinolytics: e-aminocaproic acid (EACA), tranexamic acid (AMCHA) and e-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.

Twelve peptides of the general X-SO(2)-D-Ser-Ala-Arg-OH formula (where X = methyl, phenyl, α-tolyl, p-tolyl, 4-methylbenzyl, 1-naphtyl, 2-naphtyl, 4-chlorophenyl, 4-bromophenyl, 2-mesityl, 2,4,6-triisopropylphenyl, 4-acetamidophenyl) were obtained and tested for their effect on the amidolytic activities of urokinase, thrombin, trypsin, plasmin, t-PA and kallikrein. 2,4,6-triisopropylphenyl-SO(2)-D-Ser-Ala-Arg-OH was the most selective inhibitor of urokinase and α-tolyl-SO(2)-D-Ser-Ala-Arg-OH was the most active inhibitor of uPA with K(i) value 24 µM. The compounds were tested for their in vitro antitumour activity in the following human breast cancer cells: standard MCF-7 and estrogen-independent MDA-MB-231. Four of the synthesized peptides showed cytotoxic effects against MDA-MB-231 cell lines in the range from 2.9 to 8.5 µM. The examined compound did not influence to MCF-7 cancer cells. The synthesized peptides were nontoxic to pig's erythrocytes.

Eleven peptides of the general formula H-d-Ser-Ala-Arg-NH-X, where X = (CH2)n-NH2, n = 2-9, (CH2)m-OH, m = 2-4, were obtained and tested for their effect on the amidolytic activities of urokinase, thrombin, trypsin, plasmin, t-PA, and kallikrein. H-D-Ser-Ala-Arg-NH-(CH2)5-NH2 inhibited urokinase with a Ki value of 6.3 microM.

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.