Phytochemical screening of aerial organs of wild fennel essential oils from southeast Algeria: identification of chemical composition, antioxidant, and antimicrobial activities

The purpose of this research is to investigate the chemical composition of the essential oils from the flowers, seeds, and leaves of Foeniculum vulgare Mill. collected in southeastern Algeria and to assess their antioxidant and antimicrobial properties. Essential oils were obtained by hydrodistillation and analyzed by gas chromatography-mass spectrometry. The seeds exhibited the highest yield (5.366%). Overall, 93 components have been identified: alpha-thujene (38.46%), dill ether (12.35%), cosmene (9.43%), sabinene (5.59%), and piperitenone (3.71%) were the major components in leaf essential oil; carvone (27.35%), dill ether (7.22%), 2-hydroxy-1,1,10-trimethyl-6,9-epidioxydecalin (5.67%), and 2,3-pinanediol (4.69%) in flowers; carvone (46.17%), diprene (14.32%), and cis-dihydrocarvone (9.38%) in seeds. For the first time, the antioxidant capacity of isolated oils was assessed by 2,2-diphenyl-1,1-picrirylhydrazil, 2,2 '-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid), and phosphomolybdenum methods. The flower oil showed the highest antiradical ability with inhibitory concentrations at 50% of 14.59 and 22.43 mg/mL, successively. Positive controls, ascorbic acid, and butylated hydroxytoluene showed strong scavenging activity with respective inhibitory concentrations of 50% at 6.42 and 18 mu g/mL compared to our oils. Moreover, seed oil possessed the highest power to reduce molybdenum, with an efficient concentration of 0.58 mg/mL. Additionally, the antimicrobial power was measured by observing the size of inhibition zones produced by oils after being diffused onto agar discs. Results showed that the seed and flower oils are very effective against all kinds of bacteria tested, while the leaf oil exhibited a high level of antifungal activity. F. vulgare essential oils can provide a highly promising natural option with potential use in food preservation and healthcare.