Chemical Analysis of the Essential Oils from Three Populations of Lippia dulcis Trevir. Grown at Different Locations in Southern Ecuador

Abstract

In this investigation, we have analyzed for the first time the essential oils (EOs) isolated by steam distillation of the leaves and flowers of Lippia dulcis Trevir., grown at three different locations in southern Ecuador: the Catacocha canton (Ca), the Vilcabamba parish (Vi), and the Chuquiribamba parish (Ch). Around 98.5% of the oils’ constituents were identified by Gas Chromatography-Mass Spectrometry (GC-MS) and Gas Chromatography-Flame Ionization Detector (GC-FID) analysis using a DB-5ms capillary column. Sesquiterpene hydrocarbons were predominant in the EOs (79.77, 78.22, and 76.51%, respectively). The most representative constituents of the sample from the Ca canton were β-cedrene (16.75%), δ-selinene (11.04%), and β-cubebene (12.09%), while the sample from the Vi parish was characterized by the abundant presence of β-cedrene (17.9%), δ-selinene (12.52%), and bicyclogermacrene (11.34%). β-Cedrene (18.89%), δ-selinene (11.78%), and δ-cadinene (11.07%) were the main constituents of the essential oil (EO) from the Ch parish. The likely occurrence of low amounts of thermolabile hernandulcin in the volatile oils was indicated by the presence of the fragmentation products 6-methyl-5-hepten-2-one and 3-methyl-2-ciclohexen-1-one. In summary, the study gave us a clue to the variability of Lippia dulcis chemotypes depending on the collection sites.