Essential Oil Variability of Ocimum campechianum Mill. in Southeastern Mexico: A Chemometric Approach.

Ocimum campechianum Mill. is an aromatic herb widely distributed in North America, Central America, South America, and the Caribbean. It has been used in traditional medicine since pre-Columbian times. The essential oil of O. campechianum is known for its diverse chemical composition, which influences its biological activity. This study evaluated the chemical variability of 39 samples from wild populations under different ecological conditions. Essential oil samples were isolated from aerial parts by hydrodistillation. Comprehensive qualitative and quantitative chemical profiling was performed using gas chromatography (GC)-mass spectra (MS) and GC-FID analyses. Thirty-eight chemical compounds were detected in the essential oil samples. Unsupervised and supervised multivariate techniques were employed to elucidate the underlying chemical patterns. The relative percentage area data of the metabolites were modeled using principal component analysis and hierarchical cluster analysis. For chemotype identification, a supervised model was generated using partial least squares-discriminant analysis. The eugenol chemotype was most abundant, representing 38.5% of the samples. Three new chemotypes are described: chemotype eucalyptol, with this metabolite representing 34.1%-44.4% of the relative profile area; chemotype β-caryophyllene (23.0%-35.3%); and chemotype β-elemene (24.6%-33.2%). This assessment offers a robust framework for chemotype differentiation, providing deeper insights into the chemical diversity and potential applications of the essential oil of this species.