CONICET | Buscador de Institutos y Recursos Humanos

Biocidal activity of cationic surfactants turns them into widely used active ingredientspresent in disinfectant formulations against bacteria, fungi and viruses. In this context,the aim of this work was to deepen into the biocidal mechanism of an arginine-basedsurfactant obtained by means of enzymatic biocatalysis in our laboratory.The effect of Nα-benzoyl-L-arginine dodecylamide (Bz-Arg-NHC12) on the biophysicalproperties of bacterial and mammalian virus membrane models was studied usingan Escherichia coli lipid extract (ECEx) and a mammalian lipid mixture (POPC/16:0 SM/Cho 1:1:1, MVM). First, Bz-Arg-NHC12 insertion into lipid monolayers was analyzedevaluating the critical surface pressure. The surfactant was able to insert itself into highlypacked preformed monolayers, up to initial surface pressures of 48 ± 2 and 47 ± 2 mN/mfor ECEx and MVM respectively. Moreover, Langmuir monolayer assays carried out usingdifferent molar percentages (10 and 20 mol%) of Bz-Arg-NHC12 evidenced no effect of thesurfactant on the mean molecular area at 30 mN/m. Finally, membrane stability wasinvestigated measuring the surface pressure as a function of the mean molecular areaduring three compression-expansion cycles. Changes in the molecular area at 35 mN/m(maximum surface pressure measured) revealed an opposed behavior for both testedmodels. While MVM monolayers showed an increased stability upon Bz-Arg-NH12 incorporation in a dose-dependent manner, ECEx membranes evidenced a stabilityreduction in the presence of Bz-Arg-NHC12. Similar results were found when themembrane compressibility modulus (Cs-1) was analyzed.Results evidenced that Bz-Arg-NHC12 was able not only to interact and insert itself in bothmembrane models studied, but also to modify their biophysical properties. Differentialeffects on membranes stability may have relevance in the biocidal mechanism of thesurfactant in both viruses and bacteria.206

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