Essential oil-bearing plants from Nigeria: studies on Vernonia perrottettii (leaf and stem bark), young leaves from Eucalyptus decaisneana and immature leaves of Hyptis suaveolens

The essential oils from four medicinal plants from Nigeria were obtained by hydrodistillation and analyzed by means of GC and GC/MS. The main constituents of the leaf and stem oils of Vernonia perrottettii Sch. Bip. (Asteraceae) were sesquiterpene hydrocarbons (92.1%) with abundance of b-caryophyllene (28.1% & 39.8%) and germacrene D (34.5% & 16.0%) in the leaf and stem oils, respectively. On the other hand, the leaf oil of Eucalyptus decaisneana Sm. (Myrtaceae) was dominated by the monoterpene hydrocarbons (90.6%) with a-phellandrene (31.1%), p-cymene (20.8%) and g-terpinene (11.7%) being present in large quantities. The oil composition of immature leaf of Hyptis suaveolens L. (Lamiaceae) revealed the abundance of b-caryophyllene (22.3%), a-phellandrene (10.6%) and caryophyllene oxide (10.3%). The compositional pattern may probably lead to the delineation of a new chemotype of this specie