Chemical composition and chelating activity of Ruta chalepensis L. (Rutaceae) essential oil as influenced by phenological stages and plant organs

Chemical composition and chelating activity of Ruta chalepensis L. essential oils collected from the south-east of Tunisia at the vegetative and the flowering stages were investigated. Essential oils were extracted by hydrodistillation from different organs (leaves, flowers and stems) and analyzed by gas chromatography-flame ionization detector (GC-FID) and GC-mass spectrometry (GC-MS) techniques. The highest essential oil yields were obtained at the flowering stage with a maximum in the flowers (1.8-1.9%). Twenty-five compounds were identified in different essential oils, where ketones and esters constituted the main chemical classes. 2-Nonanone (17.2-25.9%), 2-undecanone (19-37.2%) and octyl acetate (9.1-30.8%) were found to be the major compounds in all essential oils. The majority of essential oil compounds showed homogeneity with respect to the phenological stage and plant organs. At the flowering stage, stems and flowers essential oils showed the highest metal chelating activity, whose ic(50) values ranged between 160 and 180 g/mL.