Antimycotic Activity of Essential Oil of Origanum heracleoticum L. from Bulgaria Against Clinical Isolates of Candida spp.

The component composition of Bulgarian essential oil from Origanum heracleoticum L. was determined by gas chromatography and mass spectrometry analysis. Fifty-three different compounds were identified in the essential oil, with carvacrol (70.31–70.52%) and p-cymene (10.86–11.03%) determined to be the main components. The antimicrobial activity of the essential oil was determined against 138 clinical isolates of four species of Candida spp., and it was found to exhibit high antimycotic activity (minimal inhibitory concentration (MIC) between 64 μg mL−1 and 128 μg mL−1) against both fluconazole-sensitive and fluconazole-resistant strains. It was found that Bulgarian essential oil from O. heracleoticum L. disrupts the normal permeability of the cell membrane and inhibits some of the main virulence factors of medically important fungi in the genus Candida by preventing germination, transition to the filamentous stage of growth and the production of hydrolytic enzymes.