Antifungal activity of essential oils extracted from Agastache mexicana ssp. xolocotziana and Porophyllum linaria against post-harvest pathogens
Zaida N. Juárez, Luis R. Hernández, Hagar Bach, Eugenio Sánchez-Arreola, Horacio Bach
Department of Medicine, Division of Infectious Diseases, University of British Columbia, 2660 Oak Street, Vancouver, BC V6H 3Z6, Canada.
The use of synthetic chemical fungicides to protect post-harvested grains, vegetables, and fruits raises concerns due to the potential negative impact of these chemicals on the environment and human health. The chemical composition and antifungal activity of essential oils extracted from the endemic Mexican plants Agastache mexicana ssp. xolocotziana and Porophyllum linaria were studied in order to evaluate their efficacy as a substitute for synthetic chemical fungicides. Hydro-distillation and GC–MS were used to extract and identify the components of the oils, respectively. Estragole and methyl eugenol were identified as major components of A. mexicana essential oil, whereas linoleic acid and phytol were the major components in P. linaria. These oils were tested against eleven fungal strains isolated from stored wheat grains. Toxicity of the essential oils was investigated using human-derived macrophages and the brine shrimp assay, while inflammatory responses were evaluated by measuring secretion of the cytokines IL-6 and TNF-α using human-derived macrophages. Results show potent antifungal activity against the panel of fungi tested, with MICs ranging from 0.3 to 30 μg/mL for A. mexicana, and 0.0069 to 0.92 μg/mL for P. linaria. A moderated toxicity was calculated, but no inflammatory responses were observed, suggesting that these essential oils may be used as a substitute for synthetic chemical fungicides used in post-harvested grain protection.
Keywords: Agastache mexicana; Porophyllum linaria; Post-harvest pathogens; Antifungal activity; Essential oils; Toxicity.