In vitro Inhibitory Action of the Essential Oils of Origanum Vulgare and Rosmarinus Officinalis against Aspergillus Fumigatus

Aspergillus fumigatus is the main etiological agent of aspergillosis. Considering azole antifungal drug resistance in A. fumigatus, which compromises treatment, new alternatives are needed. Among them, essential oils (EOs) can be an alternative treatment, having shown positive results in inhibiting phytopathogenic fungi in vitro. We aimed to determine the in vitro antifungal activity of Origanum vulgare L. subsp. hirtum (Link) (oregano) and Rosmarinus officinalis L. (rosemary) EOs alone and in association (O. vulgare+R. officinalis) against A. fumigatus. EOs were analyzed by gas chromatography (GC-FID and GC/MS systems), and analyses showed that the major components of O. vulgare EO were carvacrol (67.8%), p-cymene (14.8%), and thymol (3.9%); for R. officinalis, they were the monoterpenes 1,8-cineole (49.1%), camphor (18.1%) and α-pinene (8.1). For biological assays, five EO concentrations, 0.2; 0.4; 0.6; 0.8 and 1.0%, were used in disk diffusion and agar dilution tests for 21 days. In disk diffusion, O. vulgare EO alone and in association (O. vulgare+R. officinalis) showed fungicidal activity at all concentrations. In agar dilution, inhibitory action was demonstrated from 0.6% for O. vulgare EO and in association (O. vulgare+R. officinalis). R. officinalis EO at 1.0% showed no fungal growth, determining the minimum inhibitory concentration (MIC). The present study demonstrated inhibitory actions of O. vulgare and R. officinalis EOs in A. fumigatus. GC analyses corroborated the literature regarding their antibacterial and antifungal effects. However, further in vitro and in vivo studies are needed to evaluate EOs as alternative antifungals for treating aspergillosis.