Origanum vulgare L. essential oil effect against Candida spp. biofilm formation

Targeting biofilms formation, which is a major virulence attributes of Candida spp. [1], could be used not only to decrease pathogenicity, but also to potentiate conventional antifungals decreasing drug resistance, doses and toxicity. Essential oils, have emerged as a novel strategy to inhibit biofilms and to potentiate conventional antifungals [2]. In this study we evaluated the antivirulence effects of Origanum vulgare L. essential oil (O-EO) against Candida spp. and its combination with fluconazole and nystatin against biofilms.

First, we obtained de minimal inhibitory concentration (MIC) for Candida albicans strains ATTCC 90029 (0.01 mg/L) and ATCC 10231 (0.97 mg/L) and for non-albicans strains ATCC CD36 (2.6 mg/L) and ATCC 6258 (5.3 mg/L). We evaluated the effect on adhesion (through crystal violet assay), changes in morphogenesis and the antibiofilm effect on the maturation stage (through a modified scratch assay and viability by MTT reduction assay), and combination studies between fluconazole/nystatin and O-EO (by the microdilution checkerboard assay). O-EO significantly inhibited morphogenesis for the four strains assayed by at least 50% and inhibited adhesion more than 60%. In the scratch assay, O-EO inhibited recolonization almost completely for ATCC 90029 strain (97% inhibition) and by 50% in ATCC 10231. The IC50 for viability of biofilms in ATCC 90029 and ATCC10231 strains was 7.4 and 2.8 mg/L, respectively. And the checkerboard assay showed that O-EO was able to synergistically interact with fluconazole and nystatin. This study demonstrates that the use of O. vulgare could be a strategy against virulence patterns and to potentiate the effect of antifungals.

Publication History

Article published online:
13 December 2021