Lavandula angustifolia Essential Oil Inhibits the Ability of Fusobacterium nucleatum to Produce Volatile Sulfide Compounds, a Key Components in Oral Malodor

Abstract

Oral malodor still constitutes a major challenge worldwide. A strong effort is invested in eliminating volatile sulfur compound-producing oral bacteria through organic natural products such as essential oils. Fusobacterium nucleatum is a known volatile sulfur compound-producing bacteria that inspires oral malodor. The aim of the present study was to test the effect of lavender essential oil on the bacterium's ability to produce volatile sulfide compounds, the principal components of oral malodor. Lavender (Lavandula angustifolia) essential oil was extracted by hydrodistillation and analyzed using GC-MS. The minimal inhibitory concentration (MIC) of lavender essential oil on Fusobacterium nucleatum was determined in a previous trial. Fusobacterium nucleatum was incubated anaerobically in the presence of sub-MIC, MIC, and above MIC concentrations of lavender essential oil, as well as saline and chlorhexidine as negative and positive controls, respectively. Following incubation, volatile sulfur compound levels were measured using GC (Oralchroma), and bacterial cell membrane damage was studied using fluorescence microscopy. Chemical analysis of lavender essential oil yielded five main components, with camphor being the most abundant, accounting for nearly one-third of the total lavender essential oil volume. The MIC (4 µL/mL) of lavender essential oil reduced volatile sulfur compound secretion at a statistically significant level compared to the control (saline). Furthermore, the level of volatile sulfur compound production attributed to 1 MIC of lavender essential oil was in the range of the positive control chlorhexidine with no significant difference. When examining bacterial membrane damage, 2 MIC of lavender essential oil (i.e., 8 µL/mL) demonstrated the same, showing antibacterial membrane damage values comparative to chlorhexidine. Since lavender essential oil was found to be highly effective in hindering volatile sulfur compound production by Fusobacterium nucleatum through the induction of bacterial cell membrane damage, the results suggest that lavender essential oil may be a suitable alternative to conventional chemical-based anti-malodor agents.

Keywords: Fusobacterium nucleatum; Lavandula angustifolia; volatile sulfide compounds.

Figure 1

Effect of various concentrations of lavender essential oil on volatile sulphur compounds produced by F. nucleatum determined by using Oralchroma and expressed in ng/mL. Results are presented in mean ± standard deviation. Asterisk denotes differences with significant value (p < 0.05).

Figure 2

The effect of various concentrations of lavender essential oil on bacterial cell membrane integrity determined by live/dead staining via fluorescent microscopy and expressed in percentage of live and dead bacteria. Results are presented in mean ± standard deviation. Asterisk denotes differences with significant value (p < 0.05).

Figure 3

Fluorochrome microscopic images of F. nucleatum exposed to various concentrations of lavender essential oil and 0.2% chlorhexidine solution (green: live cell; red: dead cell). (a) Saline; (b) 0.5 × MIC lavender essential oil; (c) MIC lavender essential oil; (d) 2 × MIC lavender essential oil; (e) 0.2% chlorhexidine.

Figure 3

Fluorochrome microscopic images of F. nucleatum exposed to various concentrations of lavender essential oil and 0.2% chlorhexidine solution (green: live cell; red: dead cell). (a) Saline; (b) 0.5 × MIC lavender essential oil; (c) MIC lavender essential oil; (d) 2 × MIC lavender essential oil; (e) 0.2% chlorhexidine.