Development of a nanoemulsion containing essential oil from Eugenia caryophyllus and evaluation in vitro and in silico of its antibacterial and antibiofilm activity against Streptococcus mutans

This study developed a Eugenia caryophyllus nanoemulsion and evaluated its performance antimicrobial and toxicity. Nanoemulsion was produced with the high agitation method, using essential oil and a surfactant in the oily phase, and the aqueous phase consisted of a surfactant and ultrapure water. Nanoemulsion characterization included mean droplet diameter, zeta potential, and polydispersity index. Antimicrobial activity evaluation minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) and the nanoemulsion's ability to destroy and inhibit biofilm in vitro and ex vivo on bovine incisor specimens. In silico toxicity predictions were determined using Molinspiration Cheminformatics, pkCSM, ProTox-II, and OSIRIS Property Explorer software. Molecular docking was conducted using AutoDock Vina and AutoDock4 AMDock v.1.5.2 to analyze the interactions between the IL-1β, IL-6, IL-8, IL-10 and TNF-α and the eugenol. To evaluate the data, one-way analysis of variance (ANOVA) was used, followed by Tukey's test, using GraphPad Prism 8.0.1 software (GraphPad Software Inc, San Diego, CA, USA). Nanoemulsion had a mean droplet size of 117 nm, a low polydispersity index, and a zeta potential of -7.9 mV. Antimicrobial activity tests demonstrated 0.78 mg/ml MIC and 1.56 mg/mL MBC against Streptococcus. mutans. The nanoemulsion also effectively eradicated and inhibited biofilm in vitro . Genotoxicity and cytotoxicity tests confirmed the safety of the nanoemulsion for dental use. In molecular docking, eugenol demonstrated higher binding affinity to the TNF-α and lower affinity to the IL-10. This study highlights the potential of this nanoemulsion as antimicrobials in dentistry, emphasizing its natural origin and confirmed safety by the tests.