A chemical marker proposal for the Lantana genus: composition of the essential oils from the leaves of Lantana radula and L. canescens.

Essential oil extracts from the leaves of two Lantana species (L. radula Sw. and L. canescens Kunth), for which no prior analysis has been reported, were analyzed by GC-MS. This information was utilized to propose chemical markers for Lantana species so that identification between physically similar plant species can be achieved through chemical analysis. Results showed 33 constituents for L. canescens, among which beta-caryophyllene (43.9%), beta-cubebene (10.1%), elixene (8.6%), beta-phellandrene (6.1%), alpha-caryophyllene (2.6%) and dehydro-aromadendrene (2.6%) were the principle components. L. radula revealed the presence of 21 compounds, the most abundant of which were beta-cubebene (31.0%), beta-caryophyllene (20.8%), elixene (10.0%), alpha-salinene (6.4%), beta-phellandrene (6.1%), copaene (4.9%) cadinene (1.4%) and psi-limonene (1.4%). The high concentration of beta-caryophyllene in the samples tested here and those in the literature make it a good candidate for a chemical marker for Lantana species, with beta-cubebene, elixene and beta-phellandrene following as minor compounds identified more sporadically in this genus. On the other hand, Lippia species, which are morphologically similar to those from the Lantana genus, would contain limonene, citral, carvacrol, beta-myrcene, camphor and thymol as the main chemical markers. These chemical markers would be a powerful tool for maintaining quality control in the extraction of essential oils for use in medicinal applications, as well as in identification of plant specimens to a taxonomist.