Mentha spp. essential oil antifungal activity against Candida albicans biofilm

In recent years fungal infections have been increasing due to a growing number of immunosuppressed and medically compromised patients. Candida is one of the most-common agents of nosocomial bloodstream infections in the USA. The increase in resistance to classical antifungal drugs, the treatment costs, and the fact that most available antifungal agents have only fungistatic activity, justify the search for new strategies as the use of natural products. Mentha spp. are known to have medicinal activity on C. albicans. Objective: In the present study we investigated if the essential oil and fractions from Mentha sp. (MC52) from Campinas Agronomic Institute are effective in the prevention and treatment of C. albicans biofilm formation. Methods: Different parts of this plant were collected and extracted by hydrodistillation with solvents to obtain the essential oils. These oils were fractioned in dry column and were tested in vitro for their antifungal activity against C. albicans (SC-5314) using a 96-well microtiter plate model of C. albicans biofilm formation and inhibition. This model is coupled with a colorimetric XTT-reduction assay in which metabolically active sessile cells reduce a tetrazolium salt to a water-soluble orange formazan compound, which can be quantified using a microtiter-plate reader. Results: Our results showed that the essential oil from Mentha sp. exhibited antifungal activities against C. albicans biofilm formation, inhibiting biofilm formation by 60% at a concentration of 2mg/mL. The fraccions F2 and F3 had strong activity against the preformed biofilm, reducing its metabolic activity by 49% and 38% at 0.5mg/mL, respectively; and they were also strong inhibitors of biofilm formation (70% inhibition at 0.062mg/mL and 61% at 0.125mg/mL respectively). None of the others fractions had strong inhibitory effects on C. albicans biofilms. Conclusion: These fractions from Mentha sp. should be considered alternative therapeutic strategies against biofilm-associated candidiasis. Support FAPESP (07/55972-6) NIH (NIDCR).