Avaliação da atividade antimicrobiana de óleos essenciais de Eugenia spp.

Abstract

Antimicrobial resistance is one of the major current challenges in healthcare, representing one of the main threats to global health, and is strongly associated with the misuse of antibiotics, including self-medication, early discontinuation of treatment, and indiscriminateadministration. The mechanisms of microbial resistance are diverse and may involve structural and functional alterations in microbial cells. Therefore, the use of natural products as a source of antimicrobial bioactive compounds has become relevant due to their plurality ofmechanisms of action, and among these, essential oils stand out. The present study aimed to evaluate the effects of essential oils from Eugenia azeda, Eugenia luschnathiana and Eugenia uniflora against strains of Staphylococcus aureus, including a methicillin-resistant isolate(MRSA), and Candida spp., including a fluconazole-resistant isolate (FRCA). The samples were diluted in 5% DMSO, ensuring a final concentration below 2,5% in the assay, and subjected to broth microdilution, using RPMI 1640 medium buffered with MOPS (0.165 M)for the fungal assays, and Mueller-Hinton broth for the bacterial assays, at concentrations ranging from 20% to 0.04% (yeasts) and 5% to 0.01% (bacteria). Readings were performed by visual identification after 24h, with the Minimum Inhibitory Concentration (MIC) being defined as the lowest concentration capable of inhibiting 50% of fungal growth or 100% ofbacterial growth. All essential oils analysed showed antimicrobial activity. Eugenia uniflora oil stood out against Candida spp., with MIC50 below 1% for both strains (0.47% for C. parapsilosis and 0.63% for FRCA). Eugenia luschnathiana oil, in turn, showed the highest bacterial activity, with a MIC100 of 0.10% against the standard S. aureus strain, and of only0.02% against MRSA, indicating relevant potential even against the multidrug-resistant strain. Eugenia azeda, although it did not stand out among the tested strains, showed positive antimicrobial activity. These results are promising, considering the scarce literature availableon the species Eugenia azeda and Eugenia luschnathiana. However, further studies are needed to evaluate the possible mechanisms of action and the antibiofilm potential of these species.