Comparison of chemical composition and antimicrobial activity of essential oils obtained from wild and cultivated Thymus zygis

Abstract

The present study aims to examine the chemical composition of T. zygis essential oils, collected in the wild from the northern region of Morocco during the flowering phase. Additionally, their antimicrobial activities have been evaluated. Hydro-distillation was used to extract the essential oil, and gas chromatography-mass spectrometry was employed for chemical characterization. In parallel, two distinct assays were used to measure antioxidant activity: the Ferric Reducing Antioxidant Power (FRAP) and the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays. Fumigation and repellency were employed to measure insecticidal activity. The results showed that thymol (36.24%), linalool (11.49%), and o-cymene (7.54%) were the main compounds in wild T. zygis, while thymol (57.42%) and α-pinene (7.60%) were the main compounds in cultivated T. zygis. DPPH free radical scavenging capacity and reduction power were used to quantify antioxidant activity. In the 2,2-diphenyl-1-picrylhydrazyl assay, essential oils of wild T. zygis (TZS-EO) exhibited the highest antioxidant capability, with a median inhibitory concentration (IC50) value of 28.449 ± 0.424μg/mL. In the Ferric Reducing Antioxidant Power test, the highest activity was recorded in essential oils of domesticated T. zygis (TZD-EO), with a median inhibitory concentration (IC50) value of 65.393 ± 0.899μg/mL, with inhibitory percentages of 83.86 ± 0.00% and 82.30 ± 2.71%, and CMIs of 0.746 ± 0.00μg/mL against Aspergillus niger, respectively. TZS-EO and TZD-EO exhibited encouraging antifungal activity against the tested strains. Concerning the fungicidal effect, demonstrated fungicidal effects against all tested fungal strains. Both oils exhibited insecticidal activity against adult Callosobruchus maculatus, resulting in absolute mortality at 20μL/L after 2 days of exposure.