ANTIFUNGAL ACTIVITY OF THREE ESSENTIAL OIL EXTRACTS AGAINST RESISTANT STRAINS OF PATHOGENIC FUNGI

Abstract

Background: This study is part of the ongoing effort to combat antifungal resistance. The aim of this work is to determine the antifungal activity of essential oil extracts from three plants (Cymbopogon citratus [CC], Ocimum gratissimum [OG], and Cymbopogon nardus [CN])—compared to two reference compounds (fluconazole and amphotericin B)—against resistant strains (Candida albicans NR-29449 and Aspergillus fumigatus NR-45108). Methods: Oil extracts were produced using the Clevenger-type hydrodistillation technique. Hygienic quality was assessed via agar plating. Finally, the antifungal activity of the extracts was evaluated using a microdilution plate assay with RPMI medium containing 2% glucose, followed by analysis using a spectrophotometer coupled with an automated Minimum Inhibitory Concentration (MIC) reader. Results: The essential oil extracts obtained showed relatively low yields 0.46, 0.38, and 0.32, respectively for Cymbopogon citratus (CC), Ocimum gratissimum (OG), and Cymbopogon nardus (CN). No contaminating microorganisms such as aerobic mesophilic bacteria, Enterobacteriaceae, Staphylococcus aureus, Pseudomonas aeruginosa, or yeasts and molds were detected, demonstrating the good hygienic quality of our extracts. Antifungal activity was determined based on the Minimum Inhibitory Concentrations (MICs) of the oil extracts. The following MICs were determined: MIC (CC) = 0.17 µL/µL, MIC (OG) = 0.14 µL/µL, MIC (CN) = 0.25 µL/µL, and MIC (FCA) = 0.25 µL/µL for Candida albicans NR-29449. Similarly, for Aspergillus fumigatus NR-45108: MIC (CC) = 0.17 µL/µL, MIC (OG) = 0.15 µL/µL, MIC (CN) = 0.05 µL/µL, and MIC (AMPH B) = 0.25 µL/µL. Conclusion: It appears that the Minimum Inhibitory Concentrations of the extracts are all lower than those of the reference compounds. This suggests that these essential oil extracts contain molecules possessing promising antifungal properties.