Antifungal and anti-toxigenic activities of Origanum onites and Thymus capitatus essential oils and ethanolic extracts against mycotoxigenic fungi isolated from barley

Abstract

With the purpose of identifying biological substances for controlling Aspergillus-caused aflatoxin B1 and ochratoxin A contamination in cereals, particularly in barley, we assessed the efficiencies of Origanum onites and Thymus capitatus essential oils (EOs) and ethanolic extracts (EEs) under in vitro conditions. NMR and GC-TOF-MS analysis revealed the metabolite profiles with carvacrol being the major component in both EOs, and various terpenes, carbohydrates, phenols, flavonoids, and alcohols in the complex EEs. All tested EOs and EEs completely inhibited mycelial growth, sporulation, and mycotoxin production in vitro, albeit at different concentrations: O. onites EO displayed higher antifungal and anti-mycotoxigenic activities than T. capitatus EO. Notably, O. onites EO effectively protected barley grains from A. flavus, A. niger, and ochratoxin A and aflatoxin B1 contamination, during storage when applied via fumigation. Antioxidant activities of EEs were generally higher than those of EOs, with O. onites EE being the most potent antioxidant mixture.