Antifungal activity of Ferulago capillaris essential oil against Candida, Cryptococcus, Aspergillus and dermatophyte species
This study evaluates the composition, antifungal activity and mechanism of action of the essential oil of Ferulago capillaris (Link ex Spreng.) Cout. and its main components, limonene and α-pinene, against clinically relevant yeasts and moulds. Essential oil from the plant’s aerial parts was obtained by hydrodistillation and analysed by gas chromatography (GC) and gas chromatography/mass spectrometry (GC-MS). Essential oil showed high contents of limonene (30.9 %) and α-pinene (35.8 %). Minimum inhibitory concentrations (MICs) were measured according to the reference Clinical and Laboratory Standards Institute (CLSI) broth macrodilution protocols. Cell suspensions were subcultured in solid medium and the minimum fungicidal concentrations (MFCs) were rendered. The effect of essential oil on germ tube formation, mitochondrial function and ergosterol biosynthesis was investigated. Essential oil and α-pinene displayed low and similar MIC and MFC values against tested organisms (0.08 to 5.0 μL/mL), while limonene showed a weaker activity (0.32 to 20 μL/mL). Essential oil inhibited germ tube formation at sub-inhibitory concentrations on Candida albicans. The exposure of C. albicans to the essential oil resulted in impairment of mitochondrial functions in a dose-dependent manner. No difference in ergosterol content was observed in essential oil-treated C. albicans. F. capillaris and α-pinene display a broad fungicidal activity. The fungicidal activity of F. capillaris on C. albicans can be related to an induced oxidative stress which affects enzymes activity and the membrane potential of mitochondria. The essential oil of F. capillaris was shown to have potential for use in the development of clinically useful therapeutic preparations, particularly for topical application in the management of superficial mycoses.
KeywordsFluconazole American Type Culture Collection Ergosterol Limonene Germ Tube
The authors are grateful to Fundação para a Ciência e a Tecnologia (FCT) through grants PEst-OE/SAU/UI0177/2011, CEQUIMED-PEst-OE/SAU/UI4040/2011 and PEst-C/EQB/LA0006/2011. G. Lopes (SFRH/BD/61565/2009) is indebted to FCT, FSE and POPH for the grant.
Thanks are also due to Dra Ana Cristina Tavares (CEF/Faculty of Pharmacy, University of Coimbra) for her help in prospecting plant material, and Prof. Alice Santos Silva and Dr. Elísio Costa for their help in the toxicity assays.
Conflict of interest
No conflict to disclose.
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