Variation in Volatile Leaf Oils of Twelve Eucalyptus Species Harvested from Hajeb Layoun Arboreta (Tunisia)

Hydrodistillation of the dried leaves of twelve species of the genus Eucalyptus L' Hér ., i.e., E. brockwayi C. A. Gardn ., E. gracilis F. Muell ., E. gillii Maiden , E. largiflorens F. Muell ., E. loxophleba Benth ., E. occidentalis Endl ., E. oldfieldii F. Muell ., E. salmonophloia F. Muell ., E. sargentii Maiden , E. stricklandii Maiden , E. torquata Luehm ., and E. woodwardii Maiden , harvested from Hajeb Layoun arboreta (region of Kairouan, central Tunisia) in January 2005, afforded essential oils in yields varying from 0.5±0.1 to 5.7±0.5%, dependent on the species. E. sargentii and E. brockwayi provided the highest and the lowest percentage of essential oil amongst all the species examined, respectively. Analysis by GC (RI) and GC/MS allowed the identification of 133 components, representing 92.9–98.8% of the total oil. The contents of the different samples varied according to the species. The main components were 1,8‐cineole, terpinen‐4‐ol, α‐pinene ( 2 ), p‐cymene, aromadendrene ( 1 ), globulol ( 5 ), trans‐pinocarveol ( 6 ), spathulenol ( 7 ), β‐eudesmol, torquatone ( 3 ), and 4‐methylpentan‐2‐yl acetate ( 8 ). The principal component analysis and the hierarchical clustering indicated that the volatile leaf oil composition of the twelve Eucalyptus species could be clearly differentiated.