Antifungal activity and the effect of the essential oil of Lippia origanoides Kunth on Aspergillus mycotoxins production

Abstract

Lippia origanoides (Verbenaceae) is an aromatic plant of great importance in Brazilian medicine. The antifungal and antimycotoxigenic effects of Lippia origanoides essential oil (LEO) on Aspergillus carbonarius, Aspergillus flavus and Aspergillus ochraceus were investigated. The LEO was obtained by hydrodistillation, and it was characterized by GC-FID and GC-MS. The antifungal activity was determined by mycelial growth and mycotoxin and ergosterol assays. Scanning electron microscopy was used to evaluate the effect of the LEO on the plasma membrane of fungi. The main constituents in the LEO were carvacrol (58.72%), ρcymene (15.37%) and γ-terpinene (12.73%). Significant fungicidal effects of LEO against A. carbonarius (0.24 μL/mL), A. flavus (0.98 μL/mL) and A. ochraceus (0.98 μL/mL) were observed. A reduction in the ochratoxin A synthesis that ranged from 92.03 to 98.02% and from 81.72 to 96.92% for the fungal species A. carbonarius and A. ochraceus, respectively, was observed in the presence of LEO. The production of aflatoxin B1 and B2 was qualitatively inhibited. The biosynthesis of ergosterol was significantly inhibited by the application of LEO, and morphological alterations and damage to the integrity of the fungal cell membrane were observed. The LEO has a high potential for use as an antifungal and antimycotoxigenic agent against A. carbonarius, A. flavus and A. ochraceus.