Chemical Characterization of the Essential Oils of Eucalyptus.grandis×Eucalyptus.urophylla Hybrids and Six Pure Eucalyptus species Grown in Guangxi (China)

Hydrodistillation of the fresh leaves of E.grandis×E.urophylla hybrids and pure species E.grandis, E.urophylla, E.pellita, E.camaldulensis, E. dunni, and E.saligna collected from the trees grown in Guangxi Huangmian Forest (China), afforded essential oils in yields varying from 0.24±0.15% to 5.36±0.28%, according to the species. Analysis by GC (FID) and GC/MS allowed the identification of 67 compounds, representing 82.55% to 91.03% of the total oil composition. The dominant compounds were 1,8-cineole in E.saligna, E.urophylla, E.grandis×E.urophylla, E.grandis, E.pellita and E. dunni (67.48, 57.12, 48.21, 23.64, 20.34, 20.22%), p-Cymene in E.camaldulensis,E. dunni and E.grandis(21.32, 14.74, 13.38%), α-pinene in E.grandis and E.grandis×E.urophylla (21.77, 15.55%), α-terpinene in E. dunni and E.grandis (17.96, 9.35%), α-terpineol in E.pellita and E.saligna (19.24,11.54%), respectively. Hierarchical Cluster Analysis separated the characterized essential oils into two groups, each constituting a chemotype. E.grandis×E.urophylla and E.urophylla were classified in the same group, while E.grandis in the other.