Chemical Composition and Allelopathic Potential of Essential Oils from Citharexylum spinosum L. grown in Tunisia

Citharexylum spinosum L. (Verbenaceae) also known as C. quadrangulare Jacq. or C. fruticosum L. is an exotic tree introduced many years ago in Tunisia, specially used as a street and park ornamental tree. Essential oils were obtained by hydrodistillation of the different parts (roots, stems, leaves, flowers and fruits; drupes) collected from trees grown in the area of Monastir (Tunisia). In total, 84 compounds, representing 90.1-98.4% of the whole oil composition, were identified by GC-FID and GC/MS analyses. The root essential oil was distinguished by its high content in monoterpene hydrocarbons (α-phellandrene; 30.8%) whereas that obtained from stems was dominated by sesquiterpene hydrocarbons (cuparene; 16.4%). The leaf oil was rich in an apocarotenoid derivative (hexahydrofarnesyl acetone; 26%) and an aliphatic hydrocarbon (n-nonadecane; 14.5%). Flowers oil was rich in esters (2-phenylethyl benzoate; 33.5%). Finally, drupes oil was rich in oxygenated sesquiterpenes (β-eudesmol; 33.1%). Flowers oil showed a significant phytotoxic effect against lettuce seeds germination, it induces a total inhibition when tested at 1 mg/ml. The highest inhibition of 100% was detected for flower oil tested at 1 mg/ml. Our in vitro studies suggest a possible and new alternative use of C. spinosum essential oils in herbicidal formulations, further experiments involving field conditions are necessary to confirm its herbicidal potential. This article is protected by copyright. All rights reserved.