Synthesis and biological activity of dialkylphosphocholines

Miltefosine repositioning: A review of potential alternative antifungal therapy

Fungal infections are a global health problem with high mortality and morbidity rates. Available antifungal agents have high toxicity and pharmacodynamic and pharmacokinetic limitations. Moreover, the increased incidence of antifungal-resistant isolates and the emergence of intrinsically resistant species raise concerns about seeking alternatives for efficient antifungal therapy. In this context, we review literature data addressing the potential action of miltefosine (MFS), an anti-Leishmania and anticancer agent, as a repositioning drug for antifungal treatment. Here, we highlight the in vitro and in vivo data, MFS possible mechanisms of action, case reports, and nanocarrier-mediated MFS delivery, focusing on fungal infection therapy. Finally, many studies have demonstrated the promising antifungal action of MFS in vitro, but there is little or no data on antifungal activity in vertebrate animal models and clinical trials, so have a need to develop more research for the repositioning of MFS as an antifungal therapy.

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.

Synthesis and antifungal activities of miltefosine analogs

Miltefosine is an alkylphosphocholine that shows broad-spectrum in vitro antifungal activities and limited in vivo efficacy in mouse models of cryptococcosis. To further explore the potential of this class of compounds for the treatment of systemic mycoses, nine analogs (3a-3i) were synthesized by modifying the choline structural moiety and the alkyl chain length of miltefosine. In vitro testing of these compounds against the opportunistic fungal pathogens Candida albicans, Candida glabrata, Candida krusei, Aspergillus fumigatus, and Cryptococcus neoformans revealed that N-benzyl-N,N-dimethyl-2-{[(hexadecyloxy)hydroxyphosphinyl]oxy}ethanaminium inner salt (3a), N,N-dimethyl-N-(4-nitrobenzyl)-2-{[(hexadecyloxy)hydroxyphosphinyl]oxy}ethanaminium inner salt (3d), and N-(4-methoxybenzyl)-N,N-dimethyl-2-{[(hexadecyloxy)hydroxyphosphinyl]oxy}ethanaminium inner salt (3e) exhibited minimum inhibitory concentrations (MIC) of 2.5-5.0 μg/mL against all tested pathogens, when compared to miltefosine with MICs of 2.5-3.3 μg/mL. Compound 3a showed low in vitro cytotoxicity against three mammalian cell lines similar to miltefosine. In vivo testing of 3a and miltefosine against C. albicans in a mouse model of systemic infection did not demonstrate efficacy. The results of this study indicate that further investigation will be required to determine the potential usefulness of the alkylphosphocholines in the treatment of invasive fungal infections.

Synthesis, self-aggregation and biological properties of alkylphosphocholine and alkylphosphohomocholine derivatives of cetyltrimethylammonium bromide, cetylpyridinium bromide, benzalkonium bromide (C16) and benzethonium chloride

A series of alkylphosphocholine and alkylphosphohomocholine derivatives of cetyltrimethylammonium bromide, cetylpyridinium bromide, benzalkonium bromide (C16) and benzethonium chloride have been synthesized. Their physicochemical properties were also investigated. The critical micelle concentration (cmc), the surface tension value at the cmc (γcmc), and the surface area at the surface saturation per head group (Acmc) were determined by means of surface tension measurements. The prepared compounds exhibit significant cytotoxic, antifungal and antiprotozoal activities. Alkylphosphocholines and alkylphosphohomocholines possess higher antifungal activity against Candida albicans in comparison with quaternary ammonium compounds in general. However, quaternary ammonium compounds exhibit significantly higher activity against human tumor cells and pathogenic free-living amoebae Acanthamoeba lugdunensis and Acanthamoeba quina compared to alkylphosphocholines. The relationship between structure, physicochemical properties and biological activity of the tested compounds is discussed.

Anti-Acanthamoebic properties of resveratrol and demethoxycurcumin

Acanthamoeba is an opportunist protist pathogen that is known to infect the cornea to produce eye keratitis and the central nervous system to produce fatal granulomatous encephalitis. Early diagnosis, followed by aggressive treatment using a combination of drugs is a prerequisite in successful treatment but even then, prognosis remains poor due to lack of effective drugs. The overall aim of the present study was to determine the anti-Acanthamoebic potential of natural compounds, resveratrol and curcuminoids. Adhesion and cytotoxicity assays were performed using primary human brain microvascular endothelial cells, which constitute the blood-brain barrier. Pre-exposure of organisms to 100 μg resveratrol and demethoxy curcumin prevented amoeba binding by 57% and 73%, respectively, while cytotoxicity of host cells was inhibited by 86%. In an assay for viability of amoebae in the absence of host cells, resveratrol and de-methoxy curcumin exhibited significant amoebicidal effects (23% and 25%, respectively) at 100 μg concentrations (P<0.01). Neither resveratrol nor demethoxycurcumin had any effect on the proteolytic activities of Acanthamoeba castellanii. Of both compounds, resveratrol is of most interest for further investigation, because of the selective toxicity of resveratrol on A. castellanii but not the human brain microvascular endothelial cells.

Surface-active properties of nitrogen heterocyclic and dialkylamino derivates of hexadecylphosphocholine and cetyltrimethylammonium bromide

The physico-chemical properties of dialkylamino and nitrogen heterocyclic analogues of hexadecylphosphocholine (HPC) and cetyltrimethylammonium bromide (CTAB) were investigated. The surface properties, such as the critical micelle concentration (cmc), the surface tension value at the cmc (gamma(cmc)), and the surface area at the surface saturation per head group (A(cmc)) were determined by means of surface tension measurements. Micelle size was determined using the dynamic light scattering method. The influence of dialkylamino groups and heterocyclic ring size on surface-active properties was investigated. Surface activity and micellar size of prepared analogues of HPC and CTAB were mutually compared.