Chemometric mapping reveals chemical, phenolic, and antioxidant profiles in Tanacetum polycephalum essential oils from Southwest Iran

Chemometric analysis of essential oils (EOs) and antioxidant capacity across ten Tanacetum polycephalum ecotypes revealed significant intraspecific phytochemical diversity and distinct chemotypes in this medicinal asteraceous species. EOs were examined for their chemical composition using gas chromatography-mass spectrometry. Significant differences were observed in EO yield (0.5-2.3%), total phenol content (3.2-8.7 mg GAE/g DW), and antioxidant activity (DPPH IC₅₀: 2.69-4.13 µg/ml; FRAP: 321.741-555.142 µM Fe²⁺/g) across ecotypes. β-thujone emerged as the predominant compound in most ecotypes (57.3-90.95%), while other major constituents included 1,8-cineole, borneol, terpinen-4-ol, camphor, carvotanacetone, and chrysanthenone. Principal component analysis revealed four distinct chemotypes: β-thujone-dominant, borneol/1,8-cineole, terpinen-4-ol/1,8-cineole, and intermediate β-thujone chemotypes, with clear correlations to elevational gradients. Hierarchical clustering confirmed the chemotype classification, supporting the taxonomic significance of phytochemical markers in population studies. The observed chemical diversity reflects adaptive responses to environmental pressures and genetic differentiation among populations. These findings demonstrate that T. polycephalum represents a chemically diverse species complex with potential for developing specialized cultivars for pharmaceutical, industrial, and agricultural applications based on specific chemotype selection.