Chemical Composition Of The Essential Oil And Leaf Hydrolat From Ornamental Green Frond Of Eucalyptus Cultivar Grown In Tuscany

The genus Eucalyptus, an Australian native, comprising more than 700 species belonging to the Myrtaceae family and the aromatic volatile oil steam-distilled from its foliage (EO), is among the world’s top traded essential oils in terms of volume. The study of EO has attracted much attention for its anti-microbial, antibacterial, anti-septic, fungicidal and nematicidal activities. EO has long history of use against the effect of cold, influenza, other respiratory infection, rhinitis and sinusitis. Actually, the commercial EO is mainly obtained from the leaves of the most common species of the genus Eucalyptus (i.e. E. globulus), which must contain, according to the Standards ISO, a percentage of 1,8-cineole higher than 80-85%. In this study, we aimed to evaluate the content and chemical composition of the essential oil and of the leaf hydrolat (EW) obtained from a different and less studied Eucalyptus species, such as Eucalyptus parvula L.A.S. Johnson & K.D. Hill, cultivated in Tuscany (central Italy). Fresh leaves and small apical peaks have been distilled. Distillation took place in steam at low temperatures, never exceeding 75 °C. This has allowed obtaining an essential oil (EO) and a hydrolat (EW) with a ratio (3:1) (fresh material/finished products) with high content of active secondary metabolites. Gas chromatography (GC) combined with mass spectrometry (MS) is the ideal tool to characterize and quantitate plant secondary volatile metabolites. Metabolic profiling using comprehensive two-dimensional GC (GCxGC) with time of-flight MS (TOFMS) provides a sensitive method for the direct comparison and chemical visualization of volatile components and a deeper insight into metabolite composition. The essential oil and the leaf hydrolat were analyzed by GC-MS and 2DGC-MS/TOF. An Agilent 7890a GC equipped with a 5975C MSD was used and GC×GC analyses were carried out on an SRA-Agilent GC-MS 7890B, with GC 2D system, coupled to an TOF-DS Markes detector. GC data confirmed that 1,8-cineole is higher than 85% in EO from E. parvula. Limonene and α-terpineol are over 3%. The complex volatile fraction of EW was submitted to advanced fingerprinting analysis of 2D chromatographic data. The final aim is to propose this products as innovative natural food and cosmetic additives, so extending the use of the plant beyond the predominantly ornamental.