Terpenoid composition of the leaf and stem bark essential oils of Vernonia migeodii S. Moore (Asteraceae)

Abstract

The compositions of the essential oils of the leaf and stem bark of Vernonia migeodii Moore (syn. Vernonia courtetii O. Hoffm. et Muschl.) revealed some qualitative and quantitative variation. The oils were isolated by hydrodistillation and analyzed for their constituents by means of gas chromatography (GC-FID) and gas chromatography coupled with mass spectrometry (GC/MS). While the leaf oil was entirely sesquiterpenoid in composition (85.4%), monoterpenes and sesquiterpenes occurred in the same quantity (ca. 43.5%) in the stem oil. The major constituents of the leaf oil were germacrene D (26.8%), β-caryophyllene (16.4%) and caryophyllene oxide (6.0%). However, α-phellandrene (16.3%), germacrene D (9.8%), (E)-β-farnesene (9.7%), caryophyllene oxide (8.2%) and β-caryophyllene (8.0%) predominated in the stem oi