Leaf Essential Oil from Three Exotic Mytaceae Species Growing in the Botanical Garden of Rio de Janeiro, Brazil

Abstract

The leaf essential oils of three Myrtaceae species: Melaleuca leucadendra , Lophostemon confertus and Ugni molinae , non-native to Brazil and growing in the Rio de Janeiro Botanical Garden, were obtained by hydrodistillation and analyzed by GC and GC-MS. Oil yields from fresh leaves were 0.76%, 0.08%, and 0.04%, respectively. Sixty-seven percent of M. leucadendra oil was made up of monoterpenes , wherein 1,8-cineole was largely predominant (49%), followed by α -terpineol (7.6%) and terpinen-4-ol (4.3%). The sesquiterpene profile was characterized by a significant amount of viridiflorol (29%). Oil from L. confertus was 42% monoterpenes; the most predominant constituents being α -pinene (20.8%) and α -thujene (7.1%). Total sesquiterpenes (55.4%) comprised spathulenol (28%), globulol (14%), and aromadendrene derivatives (8.5%) as the main species. U. Molinae oil was exclusively composed of sesquiterpenes, with a predominance of β -elemene (44%) followed by β -caryophyllene (7.1%), and bicyclogermacrene (6.7%); guaiol-type alcohols made up 30% of its profile. To the best of our knowledge, this is the first time U. Molinae leaf oil composition has been described. The composition of M. leucadendra oil corresponded to a chemotype described for a species growing in Cuba, but was different from that produced by M. leucadendra growing in Egypt, Tunisia, and elsewhere in Brazil. The profile of the L. confertus leaf oil showed high similarity with those described for Australian native specimens, in particular in relation to the relevant presence of α -pinene, aromadendrenes, and the guaiol-type alcohols.