The chemical composition of the aerial parts essential oils of two unexplored Centaurea species endemic of Sicily (Italy): Centaurea heywoodiana and C. phalacrica

In the present study, the chemical compositions of the essential oils from aerial parts of Centaurea heywoodiana Raimondo, Spadaro & Di Gristina (sect. Dissectae (Hayek) Dostal.) and Centaurea phalacrica Brullo, Cambria, Crisafulli, Tavilla & Sciandr. (sect. Aplolepidae (J. Arenes) Dostal.), two completely unexplored endemic species of Sicily, were evaluated by GC-MS. The main components of the essential oil of C. heywoodiana (Ch) were sesquiterpenes (52.2%), with caryophyllene oxide (29.5%) as the most abundant constituent of the oil. Carbonylic compounds (43.8%) were the principal class of the essential oil of C. phalacrica (Cp) being hexanal (12.1%) as the main metabolite. Sesquiterpene hydrocarbons were also well represented (35.4%), with β-elemene (11.7%) as the main metabolite of the class. Furthermore, a complete literature review on the composition of the essential oils of all the other taxa of Centaurea, belonging to sections Dissectae and Aplolepidae, studied so far, was carried out.