Synthesis, physicochemical properties and biological activities of novel alkylphosphocholines with foscarnet moiety.

A series of alkylphosphocholines with foscarnet moiety was synthesized. The structure of these zwitterionic amphiphiles was modified in both polar and non-polar parts of surfactant molecule. Investigations of physicochemical properties are represented by the determination of critical micelle concentration, the surface tension value at the cmc and the surface area per surfactant head group utilising surface tension measurements. Hydrodynamic diameter of surfactant micelles was determined using the dynamic light scattering technique. Alkylphosphocholines exhibit significant cytotoxic, anticandidal (Candida albicans) and antiamoebal (Acanthamoeba spp. T4 genotype) activity. The relationship between the structure, physicochemical properties and biological activity of the tested compounds revealed that lipophilicity has a significant influence on biological activity of the investigated surfactants. More lipophilic alkylphosphocholines with octadecyl chains show cytotoxic activity against cancer cells which is higher than that of the compounds with shorter alkyl chains. The opposite situation was observed in case of anticandidal and antiamoebal activity of these surfactants. The most active compounds were found to have pentadecyl chains. The foscarnet analogue of miltefosine C15-PFA-C showed the highest anticandidal activity. The minimum value of anticandidal activity of this compound is 1,4 µM thus representing the highest anticandidal activity found within the group of alkylphosphocholines.

The Synthesis, Self-Assembled Structures, and Microbicidal Activity of Cationic Gemini Surfactants with Branched Tridecyl Chains.

Cationic gemini surfactants with polymethylene spacer and linear alkyl chains containing an even number of carbon atoms have been extensively studied in the recent past, with the emphasis put on the determination of their aggregation behaviour in aqueous solution and their biological properties. However, the information on the aggregation of branched gemini surfactants with an odd number of carbon atoms in their alkyl chains is only sparsely reported in the literature. To help cover this gap in the research of cationic gemini surfactants, a series of branched bisammonium cationic gemini surfactants with an odd number of carbon atoms in alkyl chains (tridecane-2-yl chains) and a polymethylene spacer with a variable length ranging from 3 to 12 carbon atoms have been synthesized and investigated. Critical micelle concentration, which was determined by three methods, was found to be in the order 10-4 mol/L. A comparison of the obtained data of the novel series of tridecyl chain geminis with those of gemini surfactants with dodecyl chains and an identical spacer structure revealed that structural differences between both series of gemini surfactants result in different aggregation and surface properties for surfactants with 6 and 8 methylene groups in the spacer (N,N'-bis(tridecane-2-yl)-N,N,N',N'-tetramethylhexane-1,6-diaminium dibromide and N,N'-bis(tridecane-2-yl)-N,N,N',N'-tetramethyloctane-1,8-diaminium dibromide) with the cmc values 8.2 × 10-4 mol/L and 6.5 × 10-4 mol/L, respectively, as determined by surface tension measurements. Particle size analysis showed the formation of small stable spherical micelles in the interval between 2.8 and 5 nm and with zeta potential around +50 mV, which are independent of surfactant concentration and increase with the increasing spacer length. Microbicidal activity of 13-s-13 gemini surfactants was found to be efficient against Gram-positive, Gram-negative bacteria and yeast.

Silver Nanoparticles Stabilised by Cationic Gemini Surfactants with Variable Spacer Length.

The present study is focused on the synthesis and investigation of the physicochemical and biological properties of silver nanoparticles stabilized with a series of cationic gemini surfactants having a polymethylene spacer of variable length. UV-VIS spectroscopy, dynamic light scattering, scanning electron microscopy and zeta potential measurements were applied to provide physicochemical characterization of the silver nanoparticles. The mean size values of the nanoparticles were found to be in the 50 to 115 nm range. From the nanoparticle size distributions and scanning electron microscopy images it results that a population of small nanoparticles with the size of several nanometers was confirmed if the nanoparticles were stabilized with gemini molecules with either a short methylene spacer (two or four -CH2- groups) or a long spacer (12 -CH2- groups). The average zeta potential value for silver nanoparticles stabilized with gemini molecules is roughly independent of gemini surfactant spacer length and is approx. +58 mV. An interaction model between silver nanoparticles and gemini molecules which reflects the gained experimental data, is suggested. Microbicidal activity determinations revealed that the silver nanoparticles stabilized with gemini surfactants are more efficient against Gram-negative bacteria and yeasts, which has a direct relation to the interaction mechanism of nanoparticles with the bacterial cell membrane and its structural composition.

Immunomodulatory Activity of Leaf Infusions of Selected Cornaceae Species on Human Leukocytes.

Particular Cornus species are known for their edible fruits and their leaves are used as a tea in some countries. In the present study, the immunomodulatory activity of water infusions of leaves of Cornus mas (CM), C. kousa (CK), C. alba (CA), C. flaviramea (CF), C. coreana (CC) and C. amomum (CU) was tested on human leukocytes. Phagocytic and antimicrobial activity was determined for concentrations of 0.17 and 0.25 mg x mL(-1). All samples significantly enhanced the phagocytic activity of cells. Samples at the concentration of 0.17 mg x mL(-1) were in all cases, except CK, slightly more effective than those at 0.25 mg x mL(-1). The strongest bactericidal (E. coli) and also candidacidal (C. albicans) activity was exerted by CM at 0.25 mg x mL(-1). The most potent samples at the lower concentration were CF (for E. coli) and CK (for C. albicans). CC and CU were antimicrobially non-effective.

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.

Dibasic esters of ortho-/meta-alkoxyphenylcarbamic acid containing 1-dipropylamino-3-piperidinopropan-1-yl and their antimicrobial activity.

In Europe, the presence of microorganisms that have become resistant to antimicrobials as the most significant disease threat has remained. The aim of the current research was to screen the in vitro susceptibility of Staphylococcus aureus, Escherichia coli and Candida albicans to the series of dibasic esters of ortho-/meta-alkoxyphenylcarbamic acid previously known for their local anaesthetic effectiveness and to contribute for the structure - antimicrobial potency relationships study within that class of the compounds. The antimicrobial activity investigation involved determination of the minimum inhibitory concentration (MIC) by applying the microdilution method; quantitative screening was performed on a blood agar (S. aureus), Endo agar (E. coli) or on Sabouraud's agar (C. albicans). The activity against all the microorganisms tested was primarily influenced by the position of alkoxy side chain attached to lipophilic aromatic ring and by its length as well. Inspected meta-alkoxy substituted derivatives have shown higher efficiency against all chosen microorganisms than their ortho-alkoxy positional isomers. The most promising results were observed when investigating the activity of meta-alkoxy substituted molecules against E. coli with the estimated MICs in the range of 12-49 microg/ml. Furthermore, such potency was found to be quasi parabolically dependent on alkoxy chain length achieving a maximum for meta-hexyloxy derivative which has shown MIC= 12 microg/ml. Considered compound was also regarded as the most effective against S. aureus with MIC = 98 microg/ml. Evaluating the potency against C. albicans, it was revealed that no molecule within the tested set displayed MIC < 100 microg/ml.

Antimicrobial effect of para-alkoxyphenylcarbamic acid esters containing substituted N-phenylpiperazine moiety.

In current research, nine basic esters of para-alkoxyphenylcarbamic acid with incorporated 4-(4-fluoro-/3-trifluoromethylphenyl)piperazin-1-yl fragment, 6i-6m and 8f-8i, were screened for their in vitro antimicrobial activity against Candida albicans, Staphylococcus aureus and Escherichia coli, respectively. Taking into account the minimum inhibitory concentration assay (MIC), as the most active against given yeast was evaluated 8i (MIC = 0.20 mg/mL), the most lipophilic structure containing para-butoxy and trifluoromethyl substituents. Investigating the efficiency of the compounds bearing only a single atom of fluorine and appropriate para-alkoxy side chain against Candida albicans, the cut-off effect was observed. From evaluated homological series, the maximum of the effectiveness was noticed for the stucture 6 k (MIC = 0.39 mg/mL), containing para-propoxy group attached to phenylcarbamoyloxy fragment, beyond which the compounds ceased to be active. On the contrary, all the tested molecules were against Staphylococcus aureus and Escherichia coli (MICs > 1.00 mg/mL) practically inactive.

Antimicrobial effect of para-alkoxyphenylcarbamic acid esters containing substituted N-phenylpiperazine moiety

In current research, nine basic esters of para-alkoxyphenylcarbamic acid with incorporated 4-(4fluoro-/3-trifluoromethylphenyl)piperazin-1-yl fragment, 6i-6m and 8f-8i, were screened for their in vitro antimicrobial activity against Candida albicans, Staphylococcus aureus and Escherichia coli, respectively. Taking into account the minimum inhibitory concentration assay (MIC), as the most active against given yeast was evaluated 8i (MIC = 0.20 mg/mL), the most lipophilic structure containing para-butoxy and trifluoromethyl substituents. Investigating the efficiency of the compounds bearing only a single atom of fluorine and appropriate para-alkoxy side chain against Candida albicans, the cut-off effect was observed. From evaluated homological series, the maximum of the effectiveness was noticed for the stucture 6 k (MIC = 0.39 mg/mL), containing para-propoxy group attached to phenylcarbamoyloxy fragment, beyond which the compounds ceased to be active. On the contrary, all the tested molecules were against Staphylococcus aureus and Escherichia coli (MICs > 1.00 mg/mL) practically inactive.

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).

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.

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 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.

Dialkylamino and nitrogen heterocyclic analogues of hexadecylphosphocholine and cetyltrimetylammonium bromide: effect of phosphate group and environment of the ammonium cation on their biological activity.

A series of dialkylamino and nitrogen heterocyclic analogues of hexadecylphosphocholine and cetyltrimethylammonium bromide have been synthesized. The prepared compounds exhibit significant cytotoxic, antifungal and antiprotozoal activities. Alkylphosphocholines possess higher antifungal activity against Candida albicans in comparison with quaternary ammonium compounds. However, quaternary ammonium compounds exhibit significant higher activity against human tumor cells and Acanthamoeba lugdunensis compared to alkylphosphocholines. In addition, their haemolytic toxicity has been investigated. The relationship between structure and biological activity of the tested compounds is discussed.