Chemodiversity of wild populations of aromatic plants as source of valuable essential oil profiles. A study on Thymus vulgaris L. from Valencia (Spain)

Abstract

Chemodiversity of wild populations of aromatic plants is a valuable source of essential oils, whose composition may be suitable forspecific purposes according their biological activity. Furthermore, knowing the intrapopulational variability based on individualanalysis has allowed characterizing atypical profiles, which can reach high levels of active compounds. Obviously, it requires thetreatment of a high number of individual samples. In this work, a methodology to characterize T. vulgaris profiles in an area ofrecognized biodiversity was proposed and applied. After Thin Layer Chromatography (TLC) screening data of 85 individual samples,7 groups, and 13 individuals were classified. Then, 20 samples were subjected to GC/MS and GC/FID analysis, respectively. Thesedata were subjected to Hierarchical Agglomerative, Discriminant Analysis and ANOVA, which finally highlighted five profiles: (1) basedon the camphane skeleton (camphene, camphor and borneol), (2) rich in the oxygenated sesquiterpenic fraction, (3) rich in 1,8-cineole, with appreciable amounts of camphor and borneol (typical chemotype from Eastern Iberian Peninsula), (4) camphor andterpinen-4-ol as major compounds, and (5) linalool chemotype. It should be noted that the percentages of the main compounds inthese groups were higher than some of those described in the literature for similar chemotypes. In summary, the preliminaryscreening by TLC, grouping individuals with similar profiles, allowed establishing a quick first approximation to the chemodiversity ofT. vulgarisin the studied area. Furthermore, the analysis of unclassified and potentially atypical individuals has also provided valuableinformation to establish the final profiles.