Variation of Chemical Composition in Flowers and Leaves Essential Oils Among Natural Population of Tunisian Glebionis coronaria (L.) Tzvelev (Asteraceae).

The aim of this study was to assess the percentage and constituents variations in flowers and leaves essential oil of three Glebionis coronaria (L.) Tzvelev population, growing wildly in three different ecotypes (Utique, M'saken, and Sahara Lektar) in Tunisia. The chemical compositions of these essential oils were analyzed by the GC and GC/MS systems. Qualitative and quantitative differences were recorded between essential oils extracted from plants collected from the three geographical provinces and between organs of the same plant (leaves and flowers). In fact, 161 components representing 87.2 - 96.5% of the whole oils were identified. Myrcene (3.2 - 35.7%), (Z)-β-ocimene (0.6 - 23.0%), camphor (0.6 - 17.2%), cis-chrysanthenol (0 - 6.9%), cis-chrysanthenyl acetate (1.1 - 17.9%), isobornyl acetate (1.6 - 3.5%), (E)-β-farnesene (0 - 6.0%), germacrene D (0 - 8.7%), and (E,E)-α-farnesene (0.7 - 12.4%) were the predominant components in the oils. These major constituents occur in different amounts depending on the organs (leaves or flowers) and the geographical origin of the plant. The chemotaxonomic usefulness of these data was discussed according to results of principal component analysis (PCA). The scores, together with the loadings, revealed a different chemical pattern for each population.