Chemical composition of the essential oils of Centaurea formanekii Halacsy and Centaurea orphanidea Heldr. & Sart. ex Boiss. ssp. thessala (Hausskn.) Dostál, two Centaurea species growing wild in Greece.

The volatile constituents of the aerial parts of Centaureaformanekii Halacsy and the aerial parts, capitula and roots of C. orphanidea Heldr. & Sart. ex Boiss. ssp. thessala (Hausskn.) Dostal from Greece were extracted by hydrodistillation and analyzed. The main components in C. formanekii were hexadecanoic acid (13.6%), delta-elemene (9.1%), and spathulenol (6.9%). The main components in C. orphanidea ssp. thessala were gamma-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 a-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.