A mouthwash formulated with o-cymen-5-ol and zinc chloride specifically targets potential pathogens without impairing the native oral microbiome in healthy individuals

Abstract

Background: Many antimicrobial compounds in mouthwashes can have a negative impact on the oral microbiome. O-cymen-5-ol, a compound derived from a phytochemical, has a targeted mode of action and is being used as an alternative. However, its effect on the native oral microbiome is unknown.

Aim: To assess the effect of a mouthwash formulated with o-cymen-5-ol and zinc chloride on the oral microbiome of healthy individuals.

Methods: A mouthwash formulated with o-cymen-5-ol and zinc chloride was administered to a cohort of 51 volunteers for 14 days, while another cohort of 49 volunteers received a placebo. The evolution of the oral microbiome in both groups was analysed using a metataxonomic approach.

Results: Analysis of the oral microbiome showed that the mouthwash selectively targeted potential oral pathogens while maintaining the integrity of the rest of the microbiome. Specifically, the relative abundance of several potentially pathogenic bacterial taxa, namely Fusobacteriota, Prevotella, Actinomyces, Granulicatella, Abiotrophia, Lautropia, Lachnoanaerobaculum, Eubacterium (nodatum group) and Absconditabacteriales (SR1) decreased, while the growth of Rothia, a nitrate-reducing bacterium beneficial for blood pressure, was stimulated.

Conclusions: The use of o-cymen-5-ol and zinc chloride as antimicrobial agents in oral mouthwashes is a valuable alternative to classical antimicrobial agents.

Keywords: Mouthwash; cymen-5-ol; oral microbiome; pathogens; zinc chloride.

Figure 1.

Boxplots of alpha diversity indices (richness observed, Shannon, and Simpson) based on ASVs (99.9% of similarity) of each experimental group (placebo and mouthwash) at each sampling point (T0 and T14 days).

Figure 2.

Principal coordinate analysis (PCoA) plot and PERMANOVA tests based on Bray-Curtis distances (ASVs level) of oral microbiome of volunteers enrolled in the mouthwash and placebo groups at T0 and T14 days. Axes represent the two dimensions explaining the greatest proportion of variances in the communities for each analysis.

Figure 3.

Heatmap of the relative abundances of bacterial genera in both treatment groups at T0 and T14 days.

Figure 4.

Boxplots of the bacterial genera whose relative abundance (%) showed significant differences throughout the treatment in either of the two groups assessed (Wilcoxon signed-rank test for paired data; p < 0.05). *, p-value < 0.05; **, p-value < 0.01; *** p-value < 0.001. Bacteria have been classified according to the dynamics of their relative abundance after treatment. A, bacteria that display a decrease in relative abundance in the mouthwash-treated group; B, bacteria that display an increase in relative abundance in the placebo-treated group; C, bacteria that display an increase in abundance in the group treated with the mouthwash.