Seasonal Variation of Leaf, Stem and Umbel Ray Essential Oils of Bupleurum gibraltarium Lam.

Abstract

The yield and composition of essential oils from leaves, stems, umbel rays and also from whole aerial parts of Bupleurum gibraltarium Lam. (Apiaceae) were determined during the pre-flowering, full flowering, late flowering, and fruiting vegetative periods. A fruit sample was also studied for comparative purposes. Leaves (0.8–1.8% yield) and stems (0.3–0.7%) reached their maximum oil content during the late flowering period, whereas umbel rays (2.2–3.7%) reached it in full flowering. Oil samples were analyzed by capillary GC and GC/MS: components which were found in amounts greater than 2% were selected to carry out a seasonal study. In the leaf oils, sabinene (12.0–33.9%) and limonene (7.8–23.4%) were the main components, the sabinene level being minimum in full flowering and maximum in fruiting. In stem oils, sabinene (4.7–21.6%) and 2,3,4-trimethylbenzaldehyde (9.3–13.6%) were the main components, the sabinene level being minimum in pre-flowering and maximum in full flowering. In umbel ray oils, sabinene (20.7–43.1%) was the first component in all the phenological periods, followed by α-pinene (7.3–28.2%). Both monoterpenes increased their levels in late flowering and reached minimum amounts in fruiting.