Liquid and vapour-phase antifungal activities of essential oils against Candida albicans and non-albicans Candida

Abstract

BackgroundThe management of Candida infections faces many problems, such as a limited number of antifungal drugs, toxicity, resistance of Candida to commonly antifungal drugs, relapse of Candida infections, and the high cost of antifungal drugs. Though azole antifungal agents and derivatives continue to dominate as drugs of choice against Candida infections, there are many available data referring to the anticandidal activity of essential oils. Since we have previous observed a good antimicrobial activity of some essential oils against filamentous fungi, the aim of this study was to extend the research to evaluate the activity of the same oils on Candida albicans, C.glabrata and C.tropicalis clinical strains, as well as the effects of related components. Essential oils selection was based both on ethnomedicinal use and on proved antibacterial and/or antifungal activity of some of these oils. Fluconazole and voriconazole were used as reference drugs.MethodsThe minimum inhibitory concentration (MIC) and the minimal fungicidal concentration (MFC) of essential oils (thyme red, fennel, clove, pine, sage, lemon balm, and lavender) and their major components were investigated by the broth microdilution method (BM) and the vapour contact assay (VC).ResultsUsing BM, pine oil showed the best activity against all strains tested, though C.albicans was more susceptible than C.glabrata and C.tropicalis (MIC50-MIC90 = 0.06 %, v/v). On the contrary, sage oil displayed a weak activity (MIC50-MIC90 = 1 %, v/v). Thyme red oil (MIC50-MIC90 ≤ 0.0038 %, v/v for C.albicans and C.tropicalis, and 0.0078- < 0.015 %, v/v for C.glabrata), followed by lemon balm, lavender and sage were the most effective by VC. Carvacrol and thymol showed the highest activity, whereas linalyl acetate showed the lowest activity both by two methods. α-pinene displayed a better activity by BM than VC.ConclusionResults show a good activity of essential oils, mainly thymus red and pine oils, and their components carvacrol, thymol and α-pinene against Candida spp., including fluconazole/voriconazole resistant strains. These data encourage adequately controlled and randomized clinical investigations. The use in vapour phase could have additional advantages without requiring direct contact, resulting in easy of environmental application such as in hospital, and/or in school.

Assay and recommendations for the detection of vapour‐phase‐mediated antimicrobial activities

“…We demonstrated that the chemically diverse EOCs carvacrol, citral, trans‐cinnamaldehyde and linalool, and EOs rich in these EOCs, exhibit vapour‐phase‐mediated antimicrobial activity against both Candida species tested. Direct vapour‐phase antimicrobial activities were shown before for citral‐, carvacrol‐ and linalool‐rich EOs and their corresponding EOCs using different assays . Taking the variability of EO composition into account, this demonstrates that there is a degree of overlap between the direct vapour‐phase antimicrobial activity and the vapour‐phase‐mediated antimicrobial activity measured here.…”

“…Direct vapour-phase antimicrobial activities were shown before for citral-, carvacrol-and linalool-rich EOs and their corresponding EOCs using different assays. 21,23,24 Taking the variability of EO composition 25,26 into account, this demonstrates that there is a degree of overlap between the direct vapour-phase antimicrobial activity and the vapour-phase-mediated antimicrobial activity measured here. Moreover, it indicates that reliable results can be obtained using the assay that we introduced.…”

“…Their MIC and MFC against a strain of both C. albicans and C. glabrata (Table ), yielding values of ≤0.13% (v/v) for most EO(C)s. For Cinnamomum camphora ct linalool EO, Melissa officinalis EO and linalool EOC the MIC could not be determined as 0,13% (v/v) was the highest concentration that could be tested in this experimental set‐up due to cytotoxicity of the solvent DMSO. However, the anti ‐Candida activity of these EOs has been described before …”

Antibacterial activity evaluation of selected essential oils in liquid and vapor phase on respiratory tract pathogens

“…In opposite, VPT detect the effect of gaseous phase produced by EO vapor and they can be easily combined with other techniques [8]. It should be highlighted that VPT can also be adapted to other different pathogens such as fungi and viruses [15][16][17][18]. According to the result of the microbiological assays, cinnamon bark, clove, thyme, peppermint, and citronella oils showed the most potent activity in both vapor and liquid systems.…”

Thymus Plants: A Review—Micropropagation, Molecular and Antifungal Activity

“…Thymus vulgaris Candida albicans [72,86,94,99,100] Thymus vulgaris Aspergillus flavus [92] Thymus vulgaris Aspergillus ochraceus [96] Thymus eriocalyx Thymus x-porlock Aspergillus niger [98] Thymus vulgaris Penicillium chrysogenum [96] Thymus serpyllum Dermatophytes [101] Thymus schimperi Penicillium chrysogenum [66] Thymus schimperi Verticillium sp. [66] Thymus schimperi Aspergillus tubingensis [66] Thymus schimperi Aspergillus minutus [66] Thymus schimperi Beauveria bassiana [66] Thymus schimperi Microsporum gypseum [66] deformation, deterioration, collapse, and of the conidia and/or hyphae [96].…”