A Preliminary Investigation on the Antimicrobial Activity of Listerine®, Its Components, and of Mixtures Thereof

Abstract

Listerine® is one of the most popular mouthwashes worldwide and claims to combat harmful bacteria. In the past century, its recipe was changed from an essential oil mouthwash to a five-component mixture (thymol, menthol, eucalyptol, and methyl salicylate dissolved in 27% ethanol). The aim of this study was to get preliminary information about the antimicrobial activities of individual Listerine® components and their mixtures. We tested the bacterial strains Streptococcus mutans, Enterococcus faecalis, and Eikenella corrodens and the yeast Candida albicans. The established minimum inhibitory concentration (MIC) assay and the minimum bactericidal/fungicidal concentration (MBC/MFC) assay were applied. None of the combinations of two phenols at the concentrations contained within Listerine® were associated with either an additive or synergistic effect. Thymol had lower MIC and MBC/MFC values than the other Listerine® components and Listerine® against E. corrodens and C. albicans. The mixtures consisting of eucalyptol, methyl salicylate, and thymol were the most effective against S. mutans and E. faecalis and more effective than Listerine®. Our results demonstrate that the phenols and their concentrations as contained within Listerine® could be further optimized in terms of selecting those which increase their general effectiveness, at concentrations that do not induce harm.

Listerine® Products: An Update on the Efficacy and Safety

“…Interestingly, only one of the 16 clinical studies used a 22% ethanol solution as a control (Cosyn et al, 2013). Because ethanol in high concentrations contributes to the antibacterial effect (Vlachojannis et al, 2015), testing against a 5% ethanol solution (as a negative control) might be worthwhile.…”

Assessment of Listerine Cool Mint mouthwash influence on possible DNA damage measured by buccal micronucleus cytome assay-preliminary results

“…It also demonstrated that it affects cell membrane damage and hence the release of intracellular substances and changes in transmembrane potential (Shapiro and Guggenheim, 1995), probably not acting on calcium TRP channel receptors but through mitochondrial damage and stimulation on apoptosis. Then there is 3.94mM methyl salicylate for which a pilot document for the determination of the initial in vitro dose for acute toxicity testing has been found to have an LC50 value of 1.7mM (Website, 2001;Vlachojannis, 2015). Eucalyptol in Listerine has the least toxic effect (Ribeiro et al, 2006;Wang et al, 2012), but it has also been shown by SEM microscopy it can cause damage the cells (Dörsam et al, 2014;Zengin & Baysal, 2014).…”

In vitroEffect of Mouthrinse Containing Essential Oils on Proliferation and Migration of Gingival Epithelial Cells

“…Currently, limited evidence on the efficacy of EO À E is available (Antunes et al, 2015;Vlachojannis et al, 2016. In Listerine Zero® (Vlachojannis et al, 2015) and Listerine® Natural Care, the EO (phenolic compounds) are dissolved by means of a patented mechanism using sodium lauryl sulfate (SLS). In the present study, it was not possible to test the effect of the EO À E on the epithelial cell migration using our model, because cells adjacent to the wound margin were easily detached from the culture plate upon contact with a pipette tip.…”