Capitula essential oil composition of seven Centaurea species (sect. Acrocentron, Asteraceae) – Taxonomic implication and ecological significance

Abstract

In this paper, we analyzed the capitula essential oil composition of seven Centaurea species, six of which belong to Centaurea calocephala complex, and the related species Centaurea melanocephala Pančić (subgenus Acrocentron, tribus Cardueae, subtribus Centaureinae) which inhabit Balkans Peninsula. The volatile organic compounds were extracted by simultaneous distillation extraction, using Likens-Nickerson type apparatus and the oils were analyzed by GC-FID and GC-MS. In total, 146 compounds were identified (95.5–99.4% of the total oil composition). The essential oils were dominated by sesquiterpenes (39.1–81.7%). The most abundant components were β-caryophyllene (3.1–28.3%), caryophyllene oxide (4.7–31.2%), germacrene D (2.9–22.2%), followed by n-hexacosane, [2Z,6E]-farnesol, eudesma-4(15),7-dien-1-β-ol, α-cadinole, germacrene B, trans-verbenol, and hexanal that were present in some samples in relatively high abundances. The geographic region and the color of capitula were analyzed in correlation with essential oil composition. Also, all investigated species are characterized by the different amount of most dominant components, which leads to the hypothesis that they “choose” different strategies: different combination and amounts of attractants for pollinators. Ecological correlations and taxonomical implications are further discussed.