Membrane Toxicity of Antimicrobial Compounds from Essential Oils

Abstract

Natural antimicrobial compounds perform their action mainly against cell membranes. The aim of this work was to evaluate the interaction, meant as a mechanism of action, of essential oil antimicrobial compounds with the microbial cell envelope. The lipid profiles of Escherichia coli O157:H7, Staphylococcus aureus, Salmonella enterica serovar Typhimurium, Pseudomonas fluorescens, and Brochothrix thermosphacta cells treated with thymol, carvacrol, limonene, eugenol, and cinnamaldehyde have been analyzed by gas chromatography. In line with the fatty acids analysis, the treated cells were also observed by scanning electron microscopy (SEM) to evaluate structural alterations. The overall results showed a strong decrease of the unsaturated fatty acids (UFAs) for the treated cells; in particular, the C18:2trans and C18:3cis underwent a notable reduction contributing to the total UFA decreases, while the saturated fatty acid C17:0 raised the highest concentration in cinnamaldehyde-treated cells. SEM images showed that the used antimicrobial compounds quickly exerted their antimicrobial activities, determining structural alterations of the cell envelope.

Effect of cinnamon (Cinnamomum zeylanicum) essential oil supplementation on lamb growth performance and meat quality characteristics

“…These results do not confirm the in vitro reported intense antimicrobial activity of cinnamon essential oil against several microorganisms (Unlu et al, 2010). Cinnamaldehyde and eugenol have been shown to inhibit production of the essential enzymes and cause damage to the cell wall of the bacteria in experiments implemented in vitro (Di Pasqua et al, 2007). In general, it has been found that a greater concentration of essential oils is needed to achieve the same effects in foods compared to the in vitro experiments (Smid and Gorris, 1999).…”

“…It possesses intense antimicrobial (Unlu et al, 2010) and antioxidant (Prasad et al, 2009) properties. Cinnamomum zeylanicum action is mainly attributed to cinnamaldehyde and eugenol, substances that react with lipid and hydroxyl radicals converting them into stable products through their hydrogen-donating ability (Jayaprakasha et al, 2007) and inhibit production of essential enzymes by the bacteria due to the presence of a carbonyl group that binds and inactivates them and/or cause damage to the cell wall of the bacteria (Di Pasqua et al, 2007). Both Gram positive and Gram negative bacteria have been reported to be sensitive to cinnamon oil and cinnamaldehyde in in vitro experiments (Quattara et al, 1997).…”

In vitro effects of essential oils on potential pathogens and beneficial members of the normal microbiota

“…Animal trials have also demonstrated the promising effects of EOs against the colonisation and proliferation of Clostridium perfringens (Mitsch et al, 2004;Di Pasqua et al, 2007). The mechanism by which the essential oils exert their antimicrobial activity is poorly understood but the main target appears to be the cell membrane of bacterial cells (Burt, 2004;Di Pasqua et al, 2007).…”

“…Animal trials have also demonstrated the promising effects of EOs against the colonisation and proliferation of Clostridium perfringens (Mitsch et al, 2004;Di Pasqua et al, 2007). The mechanism by which the essential oils exert their antimicrobial activity is poorly understood but the main target appears to be the cell membrane of bacterial cells (Burt, 2004;Di Pasqua et al, 2007). Because of this, Gramnegative microbes are in general more resistant to the antimicrobial activity of EOs due to the presence of an outer membrane (Kalemba and Kunicka, 2003;Burt, 2004).…”

In vitro antimicrobial properties of plant essential oils thymus vulgaris, cymbopogon citratus and laurus nobilis against five important foodborne pathogens

“…are already several reports that the essential oils containing alcohol terpenoids act strongly on the cytoplasmic membrane of the microorganisms (DI PASQUA et al, 2007). The essential oil of bay can be used as an antioxidant or natural preservative due to the presence of the terpene alcohols Terpinen-4-ol, and α-Terpineol and phenols, which are also recognized as antimicrobial (BURT;REINDERS, 2004;BAKKALI et al, 2008;MITIC-CULAFIC et al, 2009).…”