Chemical composition and allelopathic potential of essential oils from Tipuana tipu (Benth.) Kuntze cultivated in Tunisia

The present work describes the chemical composition and evaluates the allelopathic effect of the hydrodistilled essential oil from roots, stems, leaves, flowers and samaras of Tipuana tipu (Benth.) Kuntze gathered in the area of Mogran (Tunisia). The chemical composition of the different parts of the species, determined by GC-FID and GC-MS, is reported for the first time. Remarkable differences were found between the constituent percentages in different studied organs. The most important compounds detected in roots were β-caryophyllene (24.1%), germacrene D (20%) and isopropylmyristate (11.7%). Whereas, in stems oil the main compounds found were 4-terpineol (14.6%) and elemicin (12.6%). Hexahydrofarnesyl acetone was the major oxygenated sesquiterpene constituent of leaves and samaras (10.2% and 19.9%, respectively). Essential from Tipuana tipu flowers was mainly rich in α-longipinene (8.3%), 1.7-dimethylnaphthalene (15.6%) and (E)-β-inone (33.8%). Allelopathic effects of the essential oils tested at different concentrations were evaluated on the seed germination and the early growth of Lactuca sativa seedlings. The highest inhibition of 100% was detected for the roots oil at the concentration of 1 mg/mL