Agnieszka Markowska

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 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.

The possible pre -and post -UVA radiation protective effect of amaranth oil on human skin fibroblast cells

Background: The health effects of Amaranth Oil (AO) are attributed to its specific chemical composition. That makes it an outstanding natural product for the prevention and treatment of ultraviolet (UV) irradiation-related pathologies such as sunburn, photoaging, photoimmunosuppression, and photocarcinogenesis. Most of the studies are taken on animal model, and there is a lack of research on the endogenous effect of AO on fibroblast level, where UVA takes it harmful place. Objective: The aim of this study was evaluation if AO can protect or abolish UVA exposure effect on human skin fibroblast. Materials and Methods: The 0.1% AO, 0.25% AO, and 0.5% AO concentration and irradiation for 15 min under UVA-emitting lamp were studied in various condition. In all experiments, the mean values for six assays ± standard deviations were calculated. Results: Pretreatment with various concentrations of AO was tested. The highest concentration of AO where cell survival was observed was 0.5%. Cytotoxicity assays provided evidence for pre- and post-UVA protective effect of 0.1% AO among three tested concentrations. The results also provide evidence that UVA has inhibitory effect on collagen biosynthesis in confluent skin fibroblast, but presence of 0.1% AO abolishes pre- and post-UVA effect comparing to other used AO concentration. The assessment results on DNA biosynthesis show the significant abolished post-UVA effect when 0.1% and 0.5% of AO were added. Conclusion: AO gives pre- and post-UVA protection in low concentration. This provides the evidence for using it not as a main protective factor against UV but as one of the combined components in cosmetic formulation. Abbreviations used: AO: Amaranth Oil.

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.