Chemical composition, seasonal variation and a new sesquiterpene alcohol from the essential oil of Lippia integrifolia

Abstract

Chemical investigations on the essential oil of Lippia integrifolia performed by column chromatography, HPLC, GC-MS, 1H- and 13C-NMR spectroscopy led to the identification of 78 components. A new sesquiterpene alcohol, trans-africanan-1α-ol (4), was characterized as a significant component of the oil. Additionally, six samples obtained at monthly intervals through the annual cycle of the shrub (November-April) were studied. The oil was characterized by large amounts of oxygenated sesquiterpenes (53.3-69.4%) and sesquiterpene hydrocarbons (14.3-27.9%), along with small amounts of monoterpenoids (1.4-2.9%). Lippifoli-1(6)-en-5-one (2), african-5-en-1α-ol (3), β-caryophyllene oxide, 4,5-seco-africanan-4,5-dione (10), trans-africanan-1α-ol (4), humulene epoxide II, integrifolian-1,5-dione (1) and lippifoli-1(6)-en4β-ol-5-one (7) were the main oxygenated constituents. Although the qualitative composition appeared to be constant, there were large quantitative variations in the content of most components through the studied period. Copyright © 2006 John Wiley & Sons, Ltd.