Chemical diversity of wild fennel essential oils (Foeniculum vulgare Mill.): A source of antimicrobial and antioxidant activities

This study aims to provide useful information for the evaluation of wild fennel in terms of their nutritional potential and medicinal values. It is therefore important to bio-prospect the variability of molecules produc-tion and the biological properties according to plant georaphical origin. Essential oils (EOs) obtained from leaves of 12 Foeniculum vulgare Mill. populations, growing wild in Tunisia, were analyzed by GC-MS. In addi-tion, their antimicrobial activity was evaluated against eight pathogenic bacteria and fungi. The antioxidant potential of tested oils was evaluated by four different tests: Total antioxidant activity (TAA), DPPH, ABTS and reducing power assay (RPA). In addition, relationships between studied EOs by using Hiearchical Cluster-ing Analysis (HCA) based on Euclidean distance matrix and the multivariate Principal Component Analysis (PCA) were provided. All EOs were found to be rich in monoterpenes hydrocarbons (41.56-63.13%) and phe-nylpropanoids (35.87-55.29%). Moreover, Limonene (8.40-50.34%) and Methyl Chavicol (35.87%-54.28%) were the main compounds. EOs from Zaghouan displayed the best antioxidant activity (8.5 +/- 0.05 mg GAE/g DW). While, EOs from Oued Zarga exhibited the highest DPPH radical scavenging activity (IC50 = 7.7 +/- 0.43 mg/mL), and those from Ain Ghlel and Badar regions showed the highest ABTS radical scavenging activity (IC50 = 86.86 +/- 0.23 mg/mL and 87.33 +/- 0.17 mg/mL, respectively). The most important reducing power assay was found in Ain Ghlel and Charchara EOs (EC50 of 70.46 +/- 0.17 and 71.31 +/- 0.61mg/mL respectively). Results displayed the sensitivity of the tested strains to fennel EOs especially against Gram-positive strain, and EOs from Zaghouan population exhibited the highest effect against Micrococcus luteus and Staphylococcus aureus. Overall, these results can extend our knowledge of the chemical diversity of wild fennel among geographical origin and pedoclimatic conditions indicating that Tunisian natural populations of F. vulgare had different chemotypes of EOs. In this way, the current study will provide new data and encourage the use of this plant as food. Wild fennel leaf EOs were rich in phenylpropanoids and endowed with significant antibacterial and antioxidant potential, which opens a new prospect for industrial and agronomical exploitation of this species.(c) 2022 SAAB. Published by Elsevier B.V. All rights reserved.