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    Interaction of cationic surfactants with DPPC membranes: effect of a novel N-alpha-benzoylated arginine-based compound

    Year: 2021

    Journal: Amino Acids, Volume 53, APR, page 609–619

    Authors: Hermet, Melisa; Elisa Fait, M.; Vazquez, Romina F.; Mate, Sabina; Daza Millone, M. Antonieta; Elena Vela, M.; Garcia, Maria Teresa; Morcelle, Susana R.; Bakas, Laura

    Organizations: MINCyT [PICT 2013-00647, PICT 2018-1651, PICT 2016-0679]; CONICET [PUE 22920170100100CO, PIP 2015-2017 1120201501 00671CO]; UNLP [11X-828, 11/X861]; CONICET fellowship

    Keywords: Arginine-based surfactants; Model biological membranes; DPPC bilayer; Antibacterial activity

    Cationic amino acid-based surfactants are known to interact with the lipid bilayer of microorganism resulting in cell death through a disruption of the membrane topology. To elucidate the interaction of a cationic surfactant synthesized in our lab, investigations involving N-alpha-benzoyl-arginine decyl amide (Bz-Arg-NHC10), and model membranes composed by 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) were done. Bz-Arg-NHC(10)was able to penetrate into DPPC monolayers up to a critical pressure of 59.6 mN m(-1). Differential scanning calorimetry revealed that as the concentration of Bz-Arg-NHC10 increased, the main transition temperature of DPPC slightly decreased. Atomic force microscopy (AFM) in situ experiments performed on supported DPPC bilayers on mica allowed monitoring the changes induced by Bz-Arg-NHC10. DPPC bilayer patches were partially removed, mainly in borders and bilayer defects for 50 mu M Bz-Arg-NHC10 solution. Increasing the concentration to 100 mu M resulted in a complete depletion of the supported bilayers. Surface plasmon resonance (SPR) experiments, carried out with fully DPPC bilayers covered chips, showed a net increase of the SPR signal, which can be explained by Bz-Arg-NHC10 adsorption. When patchy DPPC bilayers were formed on the substrate, a SPR signal net decrease was obtained, which is consistent with the phospholipids' removal observed in the AFM images. The results obtained suggest that the presence of the benzoyl group attached to the polar head of our compound would be the responsible of the increased antimicrobial activity against gram-negative bacteria when compared with other arginine-based surfactants.
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