Essential oil composition of Centaurea finazzeri and C. rupestris from North Macedonia

The essential oil composition of fresh flowering heads (capitula) and fresh aerial parts of Centaurea finazzeri Adamović and Centaurea rupestris L. (Asteraceae, Centaurea sect. Acrocentron) from Štip, North Macedonia were analyzed. The essential oils were obtained by simultaneous distillation and extraction using Likens–Nickerson type apparatus and analyzed by GC-FID/GC-MS. In total, 112 compounds were identified representing 97.0-99.2% of the total oil composition. All samples were dominated by aliphatic hydrocarbons (46.3-85.7%). The dominant compounds differed between species. The most abundant compounds of C. rupestris essential oils were hexanal (10.7%, 6.3%) for aerial parts and flowering heads, respectively, (2E)-hexanal (10.6%) and α-pinene (6.0%) for aerial parts, and hexadecanoic acid (7.2%) and 2-methyl hexyl ester Butanoic acid (4.5%) for flowering heads. The main volatile constituents of C. finazzeri oils were acetophenone (13.5%), (2E)-hexanal (12.1%), and hexadecanoic acid (6.9%) for aerial parts, and hexadecanoic acid (21,8%), heptacosane (10.3%), and nonacosane (9.1%) for flowering heads. Taxonomic implications are discussed.