Atividade antimicrobiana de nanoemulsões de óleos essenciais frente a patógenos associados a candidose e a periodontite

Abstract

The research is based on the search for therapeutic alternatives for the management of oral candidiasis and periodontitis, conditions frequently associated with dysbiosis and the formation of resilient biofilms. Although essential oils possess relevant antimicrobial properties, their clinical application is limited by high volatility, low solubility, and chemical instability. In this scenario, the use of nanoemulsions emerges as a biotechnological strategy to protect these compounds and increase their bioavailability. Therefore, the objective of the study was to develop, characterize, and evaluate the antimicrobial efficacy of nanoemulsions containing essential oils of Cymbopogon flexuosus, Ocimum basilicum, Lavandula dentata, Lavandula angustifolia, and Eugenol against opportunistic pathogens, correlating their performance with physicochemical properties and cytotoxicity profiles. For this purpose, the preparation of the colloidal systems was performed using high and lowenergy methods, followed by characterization regarding droplet size, Zeta potential, and stability. Biological activity was measured through the determination of Minimum Inhibitory Concentration (MIC) and Minimum Microbicidal Concentration (MMC) against reference strains (Candida albicans ATCC 10231 and Nakaseomyces glabrata ATCC 15126; Fusobacterium nucleatum subsp. nucleatum ATCC 25586, Veillonella parvula ATCC 10790, Porphyromonas gingivalis ATCC 33277, Prevotella melaninogenica ATCC 25845, and Eikenella corrodens ATCC 23864) and clinical isolates from patients with candidiasis and periodontitis (subgingival biofilm) using silver nanoparticles as a comparative reference, in addition to cell viability assays in human lineages. With the development of nanoemulsions that enhanced the action of essential oils against oral pathogens as a distinguishing factor. The results demonstrated that the obtained nanoemulsions presented robust stability and nanometric dimensions below 130 nm, which favored interaction with microbial membranes. It was observed that nanostructuring significantly enhanced the action of the corresponding free actives; for instance, the nanoemulsion containing Eugenol reduced the dose required to inhibit Fusobacterium nucleatum by up to eight times compared to the free oil. Additionally, the formulation containing Ocimum basilicum enabled potent antifungal action, while cytotoxicity assays indicated that the lowenergy method better preserved cell viability. It is concluded that nanoemulsions containing essential oils represent an effective and safe alternative therapy, overcoming the limitations of free-state compounds and offering a promising alternative for controlling complex oral infections and combating microbial resistance.