Antioxidant and antifungal activities in vitro of essential oils and extracts of twelve Algerian species of Thymus against some mycotoxigenic Aspergillus genera

Abstract

The aim of the study was to determine the phenolic and flavonoid content of essential oils (EOs), chloroform and ethanolic extracts of 12 Algerian Thymus species and evaluate their antioxidant and antifungal activities. EOs (1.73 ± 0.30–15.00 ± 1.24 μg/mg), chloroform extracts (33.8 ± 2.42–160.93 ± 3.88 μg/mg) and ethanol extracts (27.01 ± 3.56 –148.46 ± 4.40 μg/mg) showed considerable phenolic content. Flavonoids values of chloroform extracts ranged between 3.39± 0.17 and 20.27 ± 0.29 μg/ml while ethanolic extracts values ranged between 2.81 ± 0.11 and 26.64 ± 0.18 μg/mg. Results of DPPH showed that EOs, chloroform and ethanolic extracts exhibited strong radical scavenging activity (IC50 = 21.75 ± 6.54–338.22 ± 2.99 μg/ml, 22.91 ± 5.59–90.93 ± 1.36 μg/ml, and 33.51 ± 5.72–103.80 ± 4.54 μg/ml, respectively). Inhibition of β-carotene bleaching was potentially performed by all EOs (66.48 ± 2.41–94.06 ± 2.68 %), chloroform extracts (68.98± 1.58–95.30± 1.99%), and ethanolic extracts (62.15 ± 2.51–92.36± 1.15%). The antifungal activity of EOs and extracts was tested using the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC). The EOs (0.1 ± 0.00 mg/ mL – 1.06 ± 0.46 mg/mL), chloroform (0.1 ± 0.00 mg/ mL –1.06 ± 0.46 mg/mL) and ethanol (0.1 ± 0.00 mg /mL–1.6 ± 0.00 mg/mL) showed remarkable antifungal activity against mycotoxigenic Aspergillus genera. The MFC of EOs (1.0 ± 0.34 mg/mL and > 4.8 mg/mL) , chloroform (0.26 ± 0.11 mg/mL and > 1.6 mg/mL) and ethanol (0.2 ± 0.00 mg/mL and > 1.6 mg/mL) were fungicidal in nature higher than MICs. The findings of the study indicated that Thymus spp. EOs and extracts could be used as natural alternatives for food industry.