Midura-Nowaczek K

Antimicrobial Peptides and Their Analogs: Searching for New Potential Therapeutics

Antimicrobial peptides (AMPs) are an essential part of innate immunity. These compounds have been considered as potential therapeutics because of their broad-spectrum activities and proven ability to avoid antimicrobial resistance, but their clinical and commercial developments have some limitations, such as susceptibility to proteases and a high cost of peptide production. To overcome these problems, many researchers have tried to develop short active peptides, their modifications and mimics with better properties while retaining their basic features of natural AMPs such as cationic charge and the amphipathic structure.

Synthesis and activity of amides of tripeptides as potential urokinase inhibitors

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 μM.

Synthesis and Biological Evaluation of Distamycin Analogues - New Potential Anticancer Agents

Eight of analogues of distamycin, potential minor‐groove binders, were synthesized and tested for in‐vitro cytotoxicity towards human breast cancer cells MCF‐7 and MDA‐MB‐231. The method of synthesis is simple and convenient. All of the compounds 1–8 showed antiproliferative and cytotoxic effects against both cell lines in the range 3.47 to 12.53 μM for MDA‐MB‐231 and 4.35 to 12.66 μM for MCF‐7. All compounds demonstrated activity against DNA topoisomerases I and II at a concentration of 50 μM. The ethidium bromide assay showed that these compounds bind to plasmid pBR322, yet weaker than distamycin. Further investigations concerning the mechanism of cytotoxicity are now in progress, but the IC50 values suggest that synthetic distamycin analogues with a free amino group, 3–4 and 7–8, can serve as potential carriers of strong acting elements, e. g. alkylating groups.

Synthesis and activity of N-sulfonylamides of tripeptides as potential urokinase inhibitors.

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 pigs erythrocytes.

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 Ki value 5.02 μM and 5.7 μM, respectively.

Carbocyclic potential DNA minor groove binders and their biological evaluation

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.

The effect of ε-aminocaproyl-S-benzyl-L-cysteine on the t-PA activity of human saliva

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.

Effects of S-hexyl-L-cysteine derivatives on prothrombin activation and clotting time determined in the presence of heparin.

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.