Essential oil composition of south Brazilian populations of Cunila galioides and its relation with the geographic distribution

Air-dried samples of 20 Brazilian populations of Cunila galioides were extracted by steam distillation and analyzed using GS and GS–MS. A total of 40 volatile compounds were detected and identified. Fourteen compounds were presented in high concentration, (>10% of the essential oils) in at least one of the populations, and were used to analyze the relationship between the populations. Three affinity groups, which can be considered as chemotypes, were formed by the average linkage cluster analysis. The citral group was characterized by high concentrations of neral and geranial (28 ± 1.49% and 40.5 ± 1.73%, respectively), the ocimene group by high concentration of trans-β-ocimene (33.05 ± 2.54%), and the menthene group by the presence of 1,8-cineole (10.69 ± 2.93%), trans-p-2,8-menthadiene-1-ol (11.46 ± 1.54%), 1,3,8-menthatriene (10.39 ± 1.41%), and 1,5,8-p-menthatriene (7.75 ± 2.32%), as their main constituents. Geographically, the chemotypes containing citral originated from the northeast plateau of Rio Grande do Sul, whereas chemotypes containing ocimene originated from the grasslands of high altitudes of the Atlantic range, and those of the menthene group were found in a transition area between the two regions. The chemovariation observed appear to be genetically determined.