Do essential oils from plants occurring in the Brazilian Caatinga biome present antifungal potential against dermatophytoses? A systematic review.

The Caatinga is an exclusively Brazilian biome where semiarid climatic conditions promote singularities in adaptive biodiversity. Many aromatic species are found in this region possessing antifungal properties, which are attributed to their essential oils. Thus, we questioned whether essential plant oils found in the Caatinga present anti-dermatophytic potential. Dermatophytes are keratinophilic fungi that cause one of the most prevalent mycoses globally, skin infections known as dermatophytoses (tineas). Here, we provide a comprehensive report of the available published information, analyzing the methods used to evaluate the antifungal activity, verifying the quality of the evidence and possible clinical applications, and discussing research trends in this area. The plants studied concentrated in the genera Croton (Euphorbiaceae), Lippia (Verbenaceae), Piper (Piperaceae), and Mentha (Lamiaceae). All of the studies used in vitro tests to analyze antifungal potential, and little evidence was ascertained concerning the mechanism of antifungal action. In addition, the essential oils also evidenced drug modifying activity of conventional antifungal drugs (Ketoconazole and Terbinafine). We believe that the anti-dermatophyte potential of plant essential oils occurring within the Caatinga is underestimated and that this review will encourage future chemical-pharmacological investigations into the plants within this biome.Key points• The essential oils from plants occurring in the Caatinga Biome present unknown anti-dermatophyte potential.• The studies against dermatophyte fungi concentrate on the families Lamiaceae and Verbenaceae.• In vitro assays were used to assess the anti-dermatophyte potential of the essential oils.

Antifungal activity study of the monoterpene thymol against Cryptococcus neoformans.

Cryptococcus neoformans is a yeast fungus, which causes cryptococcosis, triggered by basidiospore inhalation and consequent dissemination to the central nervous system. In this study, we analyzed the antifungal action of thymol against 10 clinical strains of C. neoformans and analyzed the interaction of this monoterpene with sterols. The MICs of thymol ranged from 20 to 51 µg/ml, while the MFC values varied between 40 and 101 µg/ml. For the strains ICB-2601 and LM-39, in the presence of ergosterol, the MIC of thymol was 64 µg/ml, and in the presence of cholesterol, its MIC was 32 µg/ml. Based on the results, thymol presents antifungal action and seems to interact with ergosterol, but not with cholesterol. Complementary studies are needed to analyze its full effects.