In Vitro Evaluation of Selected Essential Oils as Possible Antifungal and Antibiofilm Agents

Microbial biofilms are organized consortiums of microorganisms in the self-produced matrix, characterized by increased resistance to antimicrobial agents. Candida albicans belongs to the regular human microbiota, but it could be highly pathogenic. Essential oils (EOs) are widely distributed secondary metabolites, proven for various biological activities. The main goal of this investigation was to evaluate the antifungal and antibiofilm properties of EOs from Citrus limon (L.) Osbeck, C. reticulata Blanco, Nigella sativa L., and Foeniculum vulgare Mill. against C. albicans. Antifungal activity was evaluated through the disk diffusion method, followed by the determination of the minimum inhibitory (MIC) and minimum fungicidal concentration (MFC). Antibiofilm assays were implemented through the tissue culture plate method and determination of the biofilm inhibition. Zones of inhibition were detectable for all tested EOs, with the greatest activity of N. sativa (28.30±1.50 mm to 39.30±1.10 mm). MIC values ranged from 62.50 μg/ml (N. sativa) to 125 μg/ml (C. limon), and 250 μg/ml (C. reticulata and F. vulgare). All tested EOs performed an impact on the biofilm-forming capacity of tested yeast. The antibiofilm activity was species-specific and concentration-dependent. The highest antibiofilm activity was recorded for F. vulgare. Obtained results suggest that investigated EOs possess antifungal and antibiofilm potential.