Chemical Composition, Antioxidant and Antimicrobial Activities of the Essential Oil from the Leaves of Tunisian Vachellia tortilis at Various Harvest Times

The chemical composition of the essential oil from the leaves of Vachellia tortilis, collected from Tunisia, at the three developmental stages, was analysed by GC/MS. Seventy-five compounds were identified. GC-MS analysis showed qualitative and quantitative variation during Vachellia tortilis seed maturation. The essential oil was dominated by a large amount of apocarotenes (38.6-47.1%) and non-terpene derivatives (34.7-49.6%). The major components of the oil were (E)-geranylacetone (15.6-25.3%), guaiacylacetone (4.7-12.9%), p-menth-4-en-3-one (3.1-10.9%), cis-2-methyl-3-oxo-cyclohexane-butanal (4.5-8.7%), (E)-β-ionone (5.4-8.2%) and hexahydrofarnesylacetone (2.4-5.6%). The highest antioxidant activity was exhibited by essential oils at intermediate stage. Essential oils at immature and intermediate stages showed higher antimicrobial activity than those at mature stage. The present findings allowed us to choose the optimal harvesting period to have the maximum effectiveness of the essential oil in terms of biological activities.