Marián Bukovský

Synthesis and antimicrobial activity of a series of optically active quaternary ammonium salts derived from phenylalanine.

We synthesized nine quaternary ammonium compounds (QUATs) starting from phenylalanine, N-alkyl-N,N-dimethyl-(1-hydroxy-3-phenylpropyl)-2-ammonium bromides, which were prepared as optically pure substances. Five compounds were prepared as S-enantiomers and four compounds as R-enantiomers. These compounds were evaluated by their activities against bacteria and fungi. Three microbial strains were used in the study: the gram-negative bacteria Escherichia coli, the gram-positive bacteria Staphylococcus aureus and the fungi Candida albicans. The activities were expressed as minimum bactericidal or fungicidal concentrations (MBC). The most active compounds were (2S)-N-tetradecyl-N,N-dimethyl-(1-hydroxy-3-phenylpropyl)-2-ammonium bromide and (2R)-N-tetradecyl-N,N-dimethyl-(1-hydroxy-3-phenylpropyl)-2-ammonium bromide, with MBC values exceeding those of commercial benzalkoniumbromide (BAB) used as standard. The relationships between structure and biological activity of the tested QUATs were quantified by the bilinear model (QSAR) and are discussed.

Synthesis and biological activity of dialkylphosphocholines

A series of dialkylphosphocholines were prepared and evaluated for their biological activity. The antiprotozoal activity was determined against Acanthamoeba lugdunensis. Compound 15 exhibited excellent trophocidal activity. None of the tested dialkylphosphocholines exhibited better fungicidal activity against Candida albicans than miltefosine. The antineoplastic activity was determined against HeLa. The most cytotoxic was compound 10, which was more active against tumor cells as against normal cells.

Immunomodulatory activity of amphiphilic antimicrobials on mouse macrophages.

A quaternary ammonium salt (1-methyldodecyl)-trimethylammonium iodide, a structurally analogous amine oxide (1-methyldodecyl)-dimethylamine-N-oxide and the amine oxide lacking long alkyl chain trimethylamine-N-oxide were tested for their immunomodulatory activity. Inbred mice strain C57/BL6 were pretreated for 7 days by the compounds under study. The activity of elicited peritoneal macrophages was also tested. Both compounds have a long alkyl chain. In concentrations of 10(-6) M there was a significant increase of the phagocytic, candidacidal and lysozyme activities of the cells. We also observed a suppressed peroxidase activity. The colicidal activity of both the peritoneal and spleen cells were not affected. The amine oxide lacking the long alkyl chain has the same effect at high concentration. A similarity between the effects of the amphiphilic compounds on the macrophages and their antimicrobial efficacy elicits the conclusion that both activities are caused by their ability to interact with the cell membranes.

Antimicrobial activity of meta-alkoxyphenylcarbamates containing substituted N-phenylpiperazine fragment

In the present investigation, the basic esters of meta-alkoxyphenylcarbamic acid bearing variously substituted N-phenylpiperazine fragment were screened for their in vitro antimicrobial activity against Staphylococcus aureus, Escherichia coli and Candida albicans, respectively. The most effective against Escherichia coli was found the compound 6d (MIC=195,3 μg/mL) bearing simultaneously para-fluoro substituent at the 4‑phenylpiperazin-1-yl core and meta-methoxy side chain in the lipophilic part of the molecule. From whole analyzed set of the molecules the substance 8e with propoxy side chain forming meta-alkoxyphenylcarbamoyl fragment and lipophilic, sterically bulky meta-trifluoromethyl group attached at N-phenylpiperazine moiety was evaluated as the most active against Candida albicans (MIC=97,7 μg/mL). On the contrary, all investigated structures were practically inactive against Staphylococcus aureus (MIC>1000 μg/mL)

Synthesis, surface and antimicrobial properties of some quaternary ammonium homochiral camphor sulfonamides.

A group of homochiral quaternary ammonium sulfonamides bearing hydrophobic camphor derived moieties were synthesized and characterized. The described synthetic procedure is quick and efficient. The novel quaternary ammonium bromides were tested as antimicrobial and antifungal agents. They exhibited strong antimicrobial and also antifungal activity, especially N-{2-[((1S, 4R)-7,7-dimethyl-2-oxobicyclo[2.2.1]heptan-1-yl)methylsulfonamido] ethyl}-N,N-dimethyltetradecan-1-aminium bromide 1c. The surface properties of prepared compounds were evaluated by surface tension measurements and critical micelle concentration (CMC) with surface tension at CMC (γCMC) was calculated.

Relationship between aggregation properties and antimicrobial activities of alkylphosphocholines with branched alkyl chains

Synthesis of five alkylphosphocholines with branched alkyl chains (Isophol-PCs) with different length of alkyl chains was described. Isophol(8)-PC and Isophol(12)-PC represent new compounds. The physico-chemical properties of Isophol-PCs were determined, critical micelle concentration and types of formed aggregates in aqueous solutions were investigated. The biological activities of Isophol-PCs have been studied for the first time in the present study. Antimicrobial activities of alkylphosphocholines were studied against bacteria (Staphylococcus aureus, Escherichia coli), yeast (Candida albicans) and pathogenic free-living amoebae (Acanthamoeba lugdunensis and Acanthamoeba quina). A. lugdunensis and A. quina are relatively insusceptible to action of miltefosine (standard compound of alkylphosphocholines) and therefore they are good models for studies of amoebicidal action of the investigated compounds. Relationship between structure, physico-chemical and biological activities of Isophol-PCs was discussed. S. aureus and C. albicans were sensitive to action of Isophol(16)-PC, Isophol(20)-PC. E. coli was not sensitive to action of all studied alkylphosphocholines in the concentrations equal to, or less than 10mM. Among all the synthesized compounds, Isophol(16)-PC had the highest level of activity against both strains of Acanthamoeba. The minimum trophocidal concentrations of Isophol(16)-PC against A. lugdunensis and A. quina are about four times lower than the minimum trophocidal concentrations of miltefosine against both strains.

Identification and biological activity of potential probiotic bacterium isolated from the stomach mucus of breast-fed lamb

The lactic acid bacterium E isolated from the stomach mucus of breast-fed lamb was identified by sequencing of 16S rDNA fragment and species-specific PCR as Lactobacillus reuteri. Its potential antimicrobial activity and ability to modulate immune system in vitro and in vivo was determined. The growth inhibition of potential pathogens decreased from Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella enterica ser. Minnesota to Escherichia coli. The lowest inhibition activity was observed in the case of Candida albicans. The ability of L. reuteri E to modulate biological activities of human and mouse mononuclear cells was estimated in vitro and in vivo, respectively. The production of IL-1β by monocytes in vitro was significantly induced by L. reuteri E (relative activity 2.47). The ability to modulate biological activities of mononuclear cells by living L. reuteri E cells in vitro in comparison to disintegrated L. reuteri E cells in vivo differed. For example lysozyme activity in vitro was inhibited while in vivo was stimulated (relative activities 0.30 and 1.83, respectively). The peroxidase activity in vitro was stimulated while in vivo was inhibited (relative activities 1.53 and 0.17, respectively). Obtained results indicate that L. reuteri E is potential candidate to be used in probiotic preparations for animals and/or human.

Activation of human leukocytes by lipid A from E. coli strains adapted to quaternary ammonium salt and amine oxide.

The immunomodulatory activities of monophosphoryl lipid A (MLA) and diphosphoryl lipid A analogues obtained from the sensitive strain ofE. coli and from the resistant strains adapted to a quaternary ammonium salt and an amine oxide were compared. All analogues considerably stimulated the activity of human leukocytes although the analogue from the sensitive strain at a higher concentration significantly suppressed phagocytosis. The MLA analogue exhibited a suppressive effect on the microbicidal activity of human leukocytes againstE. coli and the peroxidase activity. Adaptation of bacteria to amphiphilic antimicrobial compounds, which is accompanied by chemical changes in their lipid A, only slightly reduced their immunomodulatory activity when compared with the analogue from the sensitive strain. On the other hand, the diphosphoryl analogues were less active than MLA.

Synthesis of structural analogues of hexadecylphosphocholine and their antineoplastic, antimicrobial and amoebicidal activity

Twelve derivatives of hexadecylphosphocholine (miltefosine) were synthesized to determine how the position and length of the alkyl chain within the molecule influence their biological activities. The prepared alkylphosphocholines have the same molecular formula as miltefosine. Activity of the compounds was studied against a spectrum of tumour cells, two species of protozoans, bacteria and yeast. Antitumour efficacy of some alkylphosphocholines measured up on MCF-7, A2780, HUT-78 and THP-1 cell lines was higher than that of miltefosine. The compounds showed antiprotozoal activity against Acanthamoeba lugdunensis and Acanthamoeba quina. Some of them also possess fungicidal activity against Candida albicans equal to miltefosine. No antibacterial activity was observed against Staphylococcus aureus and Escherichia coli. A difference in position of a long hydrocarbon chain within the structure with maximum efficacy was observed for antitumour, antiprotozoal and antifungal activity.

Synthesis and antimicrobial properties of camphorsulfonic acid derived imidazolium salts

Abstract A group of homochiral imidazolium salts bearing hydrophobic camphor derived moiety and ester or amide functional group were synthesized and characterized. The novel imidazolium bromides were tested as antimicrobial and antifungal agents and their minimal inhibitory concentration (MIC) was evaluated and compared to clinically used benzalkonium bromide (BAB) and carbethopendecinium bromide. The MIC values of amide derivatives 2a and 2b were slightly smaller than those for BAB, indicating their good activity. None of the prepared salts was more effective than carbethopendecinium bromide. The biocidal efficacy of amide derivatives was much higher compared to the ester analogues.