Chemical composition of the essential oils of Centaurea formanekii and Centaurea orphanidea ssp. thessala, two Centaurea species growing wild in Greece

The volatile constituents of the aerial parts of Centaurea formanekii Halacsy and the aerial parts, capitula and roots of C. orphanidea Heldr. & Sart. ex Boiss. ssp. thessala (Hausskn.) Dostál from Greece were extracted by hydrodistillation and analyzed. The main components in C. formanekii were hexadecanoic acid (13.6%), δ-elemene (9.1%), and spathulenol (6.9%). The main components in C. orphanidea ssp. thessala were γ-elemene (26.1%) and caryophyllene oxide (13.2%) in the aerial parts, hexadecanoic acid (33.5%) and heptacosane (6.3%) in the capitula, and hexadecanoic acid methyl ester (22.0%) and α-chamigrene (14.0%) in the roots. The chemotaxonomic significance with respect to other previously studied species of the same sections (Phalolepis and Achrolopus, respectively) is discussed