Due to the increasing number of infections together with the appearance of bacteria exhibiting multi-drug resistance, new antibiotics are being sought. In this context the interest of the cationic lipoids increases because of their amphiphilic structure and positive charge that can stimulates the antibacterial action of these compounds. Thus, in this work we have performed the studies on the effect of one selected triesters of phosphatidylcholine, namely 1,2-dipalmitoyl-sn-glycero-3-ethylphosphocholine (EDPPC), on the model lipid membranes. The investigations included the analysis of the impact of EDPPC on multicomponent monolayers and bilayers consisting of the lipids naturally occurring in bacterial membranes (phosphatidylethanolamines (PE), phosphatidylglycerols (PG) and cardiolipin (CL)), mixed in proportions reflecting the lipid composition of these biomembranes. In the study, the Langmuir monolayers (registered on water and PBS buffer) and liposomes as model bacterial biomembranes were applied. The obtained results demonstrate that the presence of cationic lipoid in PE/PG and PE/PG/CL systems significantly modifies their properties and molecular organization. The incorporation of EDPPC into model bacterial membranes primarily impact on the intermolecular interactions. It was shown that the strength of the interaction between the cationic lipid and the components of the model membranes depends both on the composition of the membrane as well as on the type of subphase. Furthermore, the investigated cationic lipoid leads to the decrease of the ordering of acyl chains and thus to the increase of fluidity of membranes. The obtained results allow one to propose that EDPPC may behave as antibiotic active at the level of membrane.
Keywords: Antibacterial agent; Cationic lipoid; Langmuir monolayers; Liposomes; Model membranes; Triesters of phosphatidylcholine.
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