Geographical and Climatic Variation Is Associated with Essential Oil Chemotypes While Preserving Biological Activity in Athamanta sicula L.

Several species of the genus Athamanta L. (Apiaceae) have been used since ancient times for their remarkable therapeutic properties and biological potential. Among them, Athamanta sicula L. is the only species of this genus found in Sicily, Italy. This study highlights the chemotaxonomic variability of the essential oils of this species by correlating chemical results with environmental and geographical data. Chemical analysis by GC-MS confirmed the predominance of apiol (47.5%), while spectroscopic analysis confirmed both the spectrometric characterization of the entire essential oil and the analytical purity of the isolated apiol. Biological assays showed that the apiol-rich essential oil retained antimicrobial and antibiofilm activities comparable to those of the previously characterized myristicin-rich chemotype, while displaying enhanced activity against Pseudomonas aeruginosa. Membrane-permeabilization assays supported membrane damage as a major antibacterial mechanism, whereas antioxidant tests revealed a more efficient scavenging response of the apiol-rich chemotype at lower concentrations. Overall, these findings suggest that climate-associated chemotypic variation modifies specific functional traits without substantially compromising the biological activity of the essential oil.