Chemotaxonomy of the Amazonian Unonopsis Species Based on GC-MS and Chemometric Analysis of the Leaf Essential Oils

Twelve Unonopsis specimens, comprising five species commonly found at Amazonas state (Brazil) were collected in three different sites. The leaves of the specimens were extracted by hydrodistillation and analyzed by gas chromatography coupled to mass spectrometry (GC-MS). The data treated by chemometric analysis with the objective of verify the potential of their chemical profiles for chemotaxonomic approaches. Despite the essential oils presented spathulenol and caryophyllene oxide as a main constituent in most samples, the multivariate analysis showed significant differences between the species and their collection sites. The obtained results suggest high chemical similarity between U. floribunda and U. rufescens species and proved that U. guatterioides has a distinct chemistry when compared to the analyzed species. The chemical identification points to α-guaiene, α-calacorene and widdrol as possible chemical markers for U. floribunda and U. rufescens species.