Antimicrobial Activity of Some Essential Oils—Present Status and Future Perspectives

Abstract

Extensive documentation on the antimicrobial properties of essential oils and their constituents has been carried out by several workers. Although the mechanism of action of a few essential oil components has been elucidated in many pioneering works in the past, detailed knowledge of most of the compounds and their mechanism of action is still lacking. This knowledge is particularly important for the determination of the effect of essential oils on different microorganisms, how they work in combination with other antimicrobial compounds, and their interaction with food matrix components. Also, recent studies have demonstrated that nanoparticles (NPs) functionalized with essential oils have significant antimicrobial potential against multidrug- resistant pathogens due to an increase in chemical stability and solubility, decreased rapid evaporation and minimized degradation of active essential oil components. The application of encapsulated essential oils also supports their controlled and sustained release, which enhances their bioavailability and efficacy against multidrug-resistant pathogens. In the recent years, due to increasingly negative consumer perceptions of synthetic preservatives, interest in essential oils and their application in food preservation has been amplified. Moreover, the development of resistance to different antimicrobial agents by bacteria, fungi, viruses, parasites, etc. is a great challenge to the medical field for treating the infections caused by them, and hence, there is a pressing need to look for new and novel antimicrobials. To overcome these problems, nano-encapsulation of essential oils and exploiting the synergies between essential oils, constituents of essential oils, and antibiotics along with essential oils have been recommended as an answer to this problem. However, less is known about the interactions that lead to additive, synergistic, or antagonistic effects. A contributing role of this knowledge could be the design of new and more potent antimicrobial blends, and understanding of the interplay between the components of crude essential oils. This review is written with the purpose of giving an overview of current knowledge about the antimicrobial properties of essential oils and their mechanisms of action, components of essential oils, nano-encapsulated essential oils, and synergistic combinations of essential oils so as to find research areas that can facilitate applications of essential oils to overcome the problem of multidrug-resistant micro-organisms.

Chemical Composition and Antibacterial Activity of Essential Oils from the Algerian Endemic Origanum glandulosum Desf. against Multidrug-Resistant Uropathogenic E. coli Isolates

“…EOs containing high amounts of phenolic monoterpenes, such as carvacrol and thymol are widely reported to have remarkable antibacterial properties [17]. These compounds are capable of aligning between the fatty acid chains to form a sort of channel through the membrane, and are able to interact with transmembrane proteins, thus affecting the microbial cell permeability.…”

Essential oils inhibit the bovine respiratory pathogensMannheimia haemolytica,Pasteurella multocidaandHistophilus somniand have limited effects on commensal bacteria and turbinate cellsin vitro

“…Antimicrobial activity against M. haemolytica L024A EOs exhibit their antibacterial effects through number of mechanisms including disruption of cell membranes, causing damage to the cell wall, and altering the cytoplasm (Chouhan et al 2017). The bioactive components contained in EOs can penetrate and accumulate in the phospholipid bilayer of the cell membrane, resulting in the loss of cell membrane integrity and impairing the cell metabolism (Bajpai et al, 2013).…”

“…The components of EOs are highly hydrophobic in nature, enabling them to interact with the lipids present in the cell membranes of bacteria (Burt 2004). This can disturb the cellular structure and increase permeability, resulting in bacterial cell death due to leakage of important molecules and ions (Chouhan et al 2017). In addition to inducing morphological changes, EOs elicit their antibacterial effects by producing ROS that mediate the selfdestruction of bacterial cells (Li et al 2014;Zhao and Drlica 2014;Khan et al 2017).…”

Caracterización química y actividad antibacteriana del aceite esencial de Mangifera indica L. de tres regiones de Venezuela

“…Es posible afirmar que el mecanismo de acción podría estar dirigido a inhibir la síntesis del peptidoglicano, compuesto principal de la pared celular de este grupo bacteriano. Esto se debe a la presencia de los extremos lipofílicos de la membrana celular de las bacterias Gram positivas que pueden facilitar la penetra ción de los compuestos hidrófobos [33,34,35].…”