Marlete Brum Cleff,1,*Ana Raquel Meinerz,1,*Melissa Xavier,2,*Luiz Filipe Schuch,2,*Luiz Filipe Schuch,2,*Mário Carlos Araújo Meireles,2,*Maria Regina Alves Rodrigues,3,* and João Roberto Braga de Mello4,*Author informationArticle notesCopyright and License informationDisclaimer
Abstract
The aim of this study was to evaluate the in vitro activity of the essential oil extracted from Origanum vulgare against sixteen Candida species isolates. Standard strains tested comprised C. albicans (ATCC strains 44858, 4053, 18804 and 3691), C. parapsilosis (ATCC 22019), C. krusei (ATCC 34135), C. lusitaniae (ATCC 34449) and C. dubliniensis (ATCC MY646). Six Candida albicans isolates from the vaginal mucous membrane of female dogs, one isolate from the cutaneous tegument of a dog and one isolate of a capuchin monkey were tested in parallel. A broth microdilution technique (CLSI) was used, and the inoculum concentration was adjusted to 5 x 106 CFU mL-1. The essential oil was obtained by hydrodistillation in a Clevenger apparatus and analyzed by gas chromatography. Susceptibility was expressed as Minimal Inhibitory Concentration (MIC) and Minimal Fungicidal Concentration (MFC). All isolates tested in vitro were sensitive to O. vulgare essential oil. The chromatographic analysis revealed that the main compounds present in the essential oil were 4-terpineol (47.95%), carvacrol (9.42%), thymol (8.42%) and □-terpineol (7.57%). C. albicans isolates obtained from animal mucous membranes exhibited MIC and MFC values of 2.72 μL mL-1 and 5 μL mL-1, respectively. MIC and MFC values for C. albicans standard strains were 2.97 μL mL-1 and 3.54 μL mL-1, respectively. The MIC and MFC for non-albicans species were 2.10 μL mL-1 and 2.97 μL mL-1, respectively. The antifungal activity of O. vulgare essential oil against Candida spp. observed in vitro suggests its administration may represent an alternative treatment for candidiasis.
INTRODUCTION
Candidiasis is a mycosis caused by different Candida species, which can promote superficial and systemic opportunist diseases around the world (8, 13, 19, 20). The presence of geriatric domestic animals and immunosuppressed patients, who are more susceptible to fungal infections, has increased the incidence of candidiasis (8, 18, 20). The increasing clinical importance of mycoses in veterinary medicine in addition to the emergence of more severe presentations prompts to the development of new diagnostic procedures and treatments (11, 13, 18, 19).
Most antifungals currently available for the treatment of different clinical forms of this disease have limitations that hinder their use, which makes the search for safe, efficient antimycotic products or molecules necessary (3, 11, 15, 24, 25).
In this context, research involving substances obtained from plants, especially from members of the Lamiaceae family such as Origanum vulgare , show promise. Several species of the genus Origanum have carvacrol and thymol (phenolic monoterpenes) among their main constituents; these are accompanied by other compounds such as ρ-cimene, □-terpinolene, □-terpinene, α-terpineol, linalool, 4-terpinol, germacrene-D and α-pinene, which are present in lower concentrations and also show antimicrobial activity (1, 2, 4, 5, 11, 12, 14, 21, 22, 23, 29).
Oregano has antioxidant properties and exhibits antimicrobial activity against bacteria and fungi (1, 2, 5, 6, 9, 14, 17). Some studies suggest that oregano exerts a therapeutic effect when administered to rats experimentally infected with Trichophyton rubrum (1). The antifungal activity of oregano essential oil against some species of Aspergillus such as A. parasiticus , A. niger , A. flavus and A. ochraceus was demonstrated in studies where it was shown to inhibit growth and aflatoxin production (4, 10). The effects of oregano essential oil on yeasts of medical importance such as Candida albicans isolated from human patients have also been studied (7, 11, 16). However, data concerning the impact of essential oils on yeasts of the genus Candida isolated from the vaginal mucous membrane of female dogs and other animals with a diagnosis of candidiasis are scarce to date.
The aim of the current investigation was to study the antimicrobial activities of Origanum vulgare essential oil on Candida species in order to evaluate its use as a therapy.
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Keywords: Candida, Origanum vulgare, essential oil, in vitro
