Author(s): Arbi Guetat, Faraj A. Al-Ghamdi and Ahmed K. Osman

Abstract: The chemical composition of the essential oil of the flowering branches and fresh leaves of Rosmarinus officinalis L. from Saudi Arabia was analysed by gas chromatography-based techniques (GC and GC/MS). 63 compounds were identified and amounted to 94.64 % of the total oils. The presence of oxygenated monoterpenes (51.70%) characterized the oil of Saudi Arabian rosemary. R. officinalis oil was also rich with monoterpene hydrocarbons (28.45%) and acyclic monoterpenes (8.64%). Sesquiterpenes (1.28%) were minor compounds in the oils of this plant. The dominant constituents (56.09 %) were 1,8-Cineole (23.16%), α-Pinene (19.48%) and Verbinone (13.45%).