In vitro antidermatophytic activity of Otacanthus azureus (Linden) Ronse essential oil alone and in combination with azoles

• Published in: Journal of applied microbiology 2014-02, Vol.116 (2), p.288-294
• Main Authors: Houël, E, Rodrigues, A.M.S, Jahn‐Oyac, A, Bessière, J.‐M, Eparvier, V, Deharo, E, Stien, D
• Format: Article
• Language: English
• Subjects: aerial parts; Animals; antifungal activity; Antifungal Agents - chemistry; Antifungal Agents - pharmacology; Antifungal Agents - toxicity; antifungal properties; Antimicrobial agents; Arthrodermataceae - drug effects; azoles; Azoles - pharmacology; Biological and medical sciences; Cercopithecus aethiops; chemical composition; Chemical Sciences; Chromatography; cytotoxicity; dermatomycoses; Dermatomycoses - drug therapy; dermatophytes; Drug Synergism; drugs; essential oil; essential oils; fluconazole; Fundamental and applied biological sciences. Psychology; Fungi; Fungi - drug effects; gas chromatography; Gas Chromatography-Mass Spectrometry; Humans; itraconazole; keratinophilic fungi; ketoconazole; Magnetic Resonance Spectroscopy; mass spectrometry; Microbial Sensitivity Tests; Microbiology; minimum inhibitory concentration; oils; Oils, Volatile - chemistry; Oils, Volatile - pharmacology; Oils, Volatile - toxicity; Organic chemistry; Otacanthus azureus; Plant Components, Aerial - chemistry; Plantaginaceae - chemistry; sesquiterpenoids; synergism; synergy; Trichophyton - drug effects; Trichophyton mentagrophytes; Vero Cells
• ISSN: 1364-5072; 1365-2672
• DOI: 10.1111/jam.12377

AIMS: We determined the chemical composition and investigated the antifungal activity of Otacanthus azureus (Linden) Ronse essential oil (EO) against a range of dermatophytes alone or in combination with azole antifungals. METHODS AND RESULTS: Aerial parts of the plant were steam‐distilled and the obtained oil was analysed by gas chromatography/mass spectrometry and¹H‐NMR. It was shown to be largely composed of sesquiterpenes, with the main component being β‐copaen‐4‐α‐ol. Using broth microdilution techniques, this oil was found to have remarkable in vitro antifungal activities. Minimum inhibitory concentrations as low as 4 μg ml⁻¹were recorded. The analysis of the combined effect of the O. azureus EO with azoles using chequerboard assays revealed a synergism between the EO and ketoconazole, fluconazole or itraconazole against Trichophyton mentagrophytes. Notably, the O. azureus essential oil showed low cytotoxicity to VERO cells. CONCLUSIONS: The O. azureus essential oil alone or in combination with azoles is a promising antifungal agent in the treatment for human dermatomycoses caused by filamentous fungi. SIGNIFICANCE AND IMPACT OF THE STUDY: There is much interest in the study of essential oils for the discovery of new antimicrobial drugs. This study has highlighted the antidermatophytic activity of the O. azureus EO.