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. Isophol8-PC and Isophol12-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 Isophol16-PC, Isophol20-PC. E. coli was not sensitive to action of all studied alkylphosphocholines in the concentrations equal to, or less than 10 mM. Among all the synthesized compounds, Isophol16-PC had the highest level of activity against both strains of Acanthamoeba. The minimum trophocidal concentrations of Isophol16-PC against A. lugdunensis and A. quina are about four times lower than the minimum trophocidal concentrations of miltefosine against booth strains.