Effect of Structure on the Interactions between Five Natural Antimicrobial Compounds and Phospholipids of Bacterial Cell Membrane on Model Monolayers

Abstract

Monolayers composed of bacterial phospholipids were used as model membranes to study interactions of the naturally occurring phenolic compounds 2,5-dihydroxybenzaldehyde and 2-hydroxy-5-methoxybenzaldehyde, and the plant essential oil compounds carvacrol, cinnamaldehyde, and geraniol, previously found to be active against both Gram-positive and Gram-negative pathogenic microorganisms. The lipid monolayers consist of 1,2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine (DPPE), 1,2-dihexadecanoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (DPPG), and 1,1',2,2'-tetratetradecanoyl cardiolipin (cardiolipin). Surface pressure-area (π-A) and surface potential-area (Δψ-A) isotherms were measured to monitor changes in the thermodynamic and physical properties of the lipid monolayers. Results of the study indicated that the five compounds modified the three lipid monolayer structures by integrating into the monolayer, forming aggregates of antimicrobial -lipid complexes, reducing the packing effectiveness of the lipids, increasing the membrane fluidity, and altering the total dipole moment in the monolayer membrane model. The interactions of the five antimicrobial compounds with bacterial OPEN ACCESSMolecules 2014, 19 7498 phospholipids depended on both the structure of the antimicrobials and the composition of the monolayers. The observed experimental results provide insight into the mechanism of the molecular interactions between naturally-occurring antimicrobial compounds and phospholipids of the bacterial cell membrane that govern activities.

Physiological, Biochemical, and Biophysical Characterization of the Lung-Lavaged Spontaneously-Breathing Rabbit as a Model for Respiratory Distress Syndrome

“…On the one hand, a progressive reduction of the isotherm slope in the pressure range 15–45 mN/m was detected from BAL 2 to BAL 5, with respect to Curosurf and BAL 1 (Fig 6A). Considering that the isotherm slope in this pressure range is representative of the packing density of the phospholipid chains into the monolayer[33, 34], it seems that sequential BALs become gradually organized in more fluid films. On the other hand, the required spread volume of the samples to reach a surface pressure of 15 mN/m varied significantly (Fig 6B).…”

Anti-giardia activity of hexane extract of <i>Citrus aurantifolia</i> (Christim) swingle and some of its constituents

“…Concerning geraniol, Nowotarska et al (2014) reported that this terpen was active against both Gram-positive and Gram-negative pathogenic microorganisms. Singh et al, 2002; found that geraniol-derived compounds showed very promising antimalarial in vivo activity against multidrug resistant Plasmodium yoelii.…”

Structure Dependence of Pyridine and Benzene Derivatives on Interactions with Model Membranes

“…34–36 Similarly, dipalmitoylphosphatidylethanolamine (DPPE) is utilized to model the inner leaflet of bacterial and eukaryotic membranes for drug and lipid interactions. 37–38 These two lipids have become a very appealing model interface to study drug and lipid interactions and therefore were used in this study as a model membrane interface to study the interactions of the N-containing compounds in Figure 1. 34–36,37–38 To determine the molecular-detail interactions of small aromatic N-containing compound with an interface, aerosol-OT (AOT) reverse micelles (RM) 39–42 were examined.…”

“…37–38 These two lipids have become a very appealing model interface to study drug and lipid interactions and therefore were used in this study as a model membrane interface to study the interactions of the N-containing compounds in Figure 1. 34–36,37–38 To determine the molecular-detail interactions of small aromatic N-containing compound with an interface, aerosol-OT (AOT) reverse micelles (RM) 39–42 were examined. 30 · 43–47 RMs are self-assembled microemulsion that form at low water concentration.…”