Methods: The antifungal activity of essential oils was determined by Minimum Inhibitory Concentration (MIC) and Minimal Fungicidal Concentration (MFC), obtained by the microdilution and depletion techniques, respectively. The MIC was obtained using 96-well microplates, in which were inserted 100 µL of RPMI 1640 broth doubly concentrated, 100 µL of the dilution of essential oils and 10 µL of fungal suspensions (1.5 x 106 organisms/mL). The products were diluted from initial concentration of 8% until 0.0625%. The MIC corresponded to the last dilution in which there was no presence of fungal precipitate or turbidity in the culture medium. The MFC was obtained by sowing, in Sabouraud-Dextrose agar, 10 µL aliquots of dilutions corresponding to the MIC and two immediately preceding (2MIC and 4MIC). The tests were performed in triplicate and the 2% chlorhexidine was used as control.
Results: The essential oil from C. aurantium inhibited the activity of C. albicans at concentration 0.25% (MIC and MFC), while there were no effect against C. krusei and C. tropicalis. The essential oils from C. reticulata and C. limmom did not inhibit the activity of C. albicans, C. krusei and C. tropicalis.
Conclusion: Among the evaluated essential oils, only Citrus aurantium showed antifungal activity against Candida albicans.