Isoeugenol has a non-disruptive detergent-like mechanism of action

Abstract

Isoeugenol is an essential oil constituent of nutmeg, clove, and cinnamon. Despite isoeugenol's promising antimicrobial activity, no studies have yet investigated its mode of antibacterial action at the molecular level. The aim of this study is to clarify isoeugenol's antibacterial mode of action using the Gram-negative and Gram-positive model organisms Escherichia coli and Listeria innocua, respectively. We determined the antimicrobial activity of isoeugenol against the model organisms, and examined how isoeugenol affects cell morphology, cell membrane permeabilization, and how isoeugenol interacts with phospholipid membranes using vesicle and supported lipid bilayer models. Isoeugenol demonstrated a bactericidal activity against E. coli and L. innocua that did not affect cell morphology, although the cell membrane was permeabilized. We hypothesized that the cell membrane was the primary site of action, and studied this interaction in further detail using purified membrane model systems. Isoeugenol's permeabilization of calcein-encapsulated vesicles was concentration dependent, and isoeugenol's interaction with giant unilamellar vesicles indicated increased membrane fluidity and a non-disruptive permeabilization mechanism. This contradicted membrane fluidity measurements on supported lipid bilayers (SLBs), which indicated decreased membrane fluidity. However, further investigations demonstrated that the interaction between isoeugenol and bilayers was reversible, and caused membranes to display heterogeneous topography, an increased mass, and a higher degree of hydration. In conclusion, we propose that isoeugenol interacts with membranes in a reversible non-disruptive detergent-like manner, which causes membrane destabilization. Furthermore, we argue that isoeugenol increases membrane fluidity. Our work contributes to the understanding of how essential oil constituents interact with cell components.

Effects of Tween 80 on Growth and Biofilm Formation in Laboratory Media

“…Rifampicin can be produced by Amycolatopsis rifamycinica (Bala et al, 2004) and works by inhibiting RNA synthesis in bacteria (Hartmann et al, 1967). Isoeugenol is an essential oil that can be isolated from plants and it works by permeabilizing the bacterial membrane (Hyldgaard et al, 2015). Others have also observed that addition of Tween 80 has an antagonistic effect on the activity of antibacterial compounds.…”

Antibacterial isoeugenol coating on stainless steel and polyethylene surfaces prevents biofilm growth

“…Hyldgaard et al . () suggested that isoeugenol has intracellular targets, but also targets the cell membrane through a nondestructive detergent‐like mechanism that leads to increased permeability (Hyldgaard et al . ).…”

“…() suggested that isoeugenol has intracellular targets, but also targets the cell membrane through a nondestructive detergent‐like mechanism that leads to increased permeability (Hyldgaard et al . ). The apparent absence of bacteria on the isoeugenol‐coated surfaces could potentially be caused by a combination of antimicrobial and antiadhesive properties of the isoeugenol coating.…”

Multiphase thermoplastic hybrid for controlled release of antimicrobial essential oils in active packaging film

“…In recent years, the increasing consumer health concerns regarding the use of synthetic preservatives in the food chain have stimulated the demand to replace chemically synthesized preservatives with natural alternatives . Bio preservatives and naturally derived antimicrobial additives are attracting great attention because of their ability to control food‐borne pathogens and spoilage bacteria .…”