Manuka oil, an essential oil derived from the , has been traditionally used for wound care and as a topical antibacterial, antifungal, and anti-inflammatory. However, the essential oil is not well retained at mucosal sites, such as the oral cavity, where the benefits of the aforementioned properties could be utilized toward the treatment of persistent biofilms. Within this study, essential oil was incorporated into a semisolid emulsion for improved delivery. The safety profile of essential oil on human gingival fibroblasts was determined cell viability, cytotoxicity, and caspase activation. The minimal bactericidal concentration of essential oil was determined, and the emulsion’s antibiofilm effects visualized using confocal laser scanning microscopy. essential oil demonstrated a lower IC (0.02% at 48 h) when compared to the clinical control chlorhexidine (0.002% at 48 h) and displayed lower cumulative cytotoxicity. Higher concentrations of essential oil (≥ 0.1%) at 6 h resulted in higher caspase 3/7 activation, suggesting an apoptotic pathway of cell death. A minimal bactericidal concentration of 0.1% w/w was observed for 6 oral bacteria and 0.01% w/v for . Textural and rheometric analysis indicated increased stability of emulsion with a 1 : 3 ratio of essential oil: carrier oil. The optimized 5% w/w essential oil emulsion showed increased bactericidal penetrative effects on biofilms compared to oil alone and to chlorhexidine controls. This study has demonstrated the safety, formulation, and antimicrobial activity of essential oil emulsion for potential antibacterial applications at mucosal sites.
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