Variation in Volatile Leaf Oils of Seven Eucalyptus Species Harvested from Zerniza Arboreta (Tunisia)

Leaves of seven species of the genus Eucalyptus L'HER., viz., E. cladocalyx F. MUELL., E. citriodora Hook., E. diversicolor F. MUELL., E. fasciculosa F. MUELL., E. grandis W. Hill, E. ovata LABILL., and E. botryoides SM., were harvested from Zerniza arboreta (region of Sejnene, northwest of Tunisia) in June 2007. Of the latter species, leaves were collected from trees having two origins, Morocco and Italy. Hydrodistillation of the dried leaves provided essential oils in yields varying from 0.4 +/- 0.0 to 3.3 +/- 0.1%, according to the species. E. citriodora had the highest mean percentage of essential oil amongst the species examined, whereas the lowest one was obtained for E. botryoides originating from Morocco. Analysis by GC (RI) and GC/MS allowed the identification of 140 compounds, representing 92.5 to 99.4% of the total oil composition. The contents of the different samples varied according to the species. The main components were 1,8-cineole (2), followed by alpha-pinene (1), p-cymene, borneol, alpha-terpineol, cryptone, spathulenol, trans-pinocarveol (4), bicyclogermacrene (5), caryophyllene oxide, and beta-phellandrene. Principal components analysis and hierarchical cluster analysis separated the eight Eucalyptus leaf essential oils into five groups, each constituting a chemotype.