Volatile components of aerial parts of Centaurea nigrescens an C. stenolepis growing wild in the Balkans

The volatile constituents of the aerial parts of Centaurea nigrescens Willd, collected in Romania and of two samples of C. stenolepis A. Kerner from Bulgaria and Romania were obtained by hydrodistillation and analyzed. The main components of C. stenolepis were caryophyllene oxide (6.9-15.6%), hexahydrofarnesyl acetone (6.5-4.4%), heptacosane (6.0-4.9%) and p-vinyl guiacol (4.3-5.0%). The main components of C. nigrescens were caryophyllene oxide (9.9%), β-eudesmol (9.5%), spathulenol (7.6%), heptacosane (6.1%) and p-vinyl guiacol (5.5%). The chemotaxonomic significance with respect to their colocation in Sections Lepteranthus and Nigrescentes, respectively, is discussed.