P. brutia Vol. 18, July/August 2006 Journal of Essential Oil Research/445 Received: December 2004 Revised: August 2005 Accepted: November 2005 Chemical Composition of the Needle-Twig Oils of Pinus brutia Ten. Marwan W. Ghosn and Najat A. Saliba * American University of Beirut, Chemistry Department, Beirut, Lebanon Salma Y. Talhouk American University of Beirut, Plant Science Department, Beirut, Lebanon Abstract The variation in composition of the essential oils produced from different ratios of needles to terminal twigs of Pinus brutia Ten. in Lebanon was examined by GC and GC/MS. As the mass of the needles increased from 0-100% with respect to twig contents, the % oil yield decreased and the composition changed. Pure needle oil was found to be much richer in oxygenated compounds than that of pure twig oil with a corresponding reduction in amounts of monoterpene hydrocarbons. Marker compounds were chosen in order to show the chemical variation of the oils with respect to different ratio of needles to twigs distilled. By computing both physical and chemical variations, it is suggested that a fair compromise between the yield and the concentration of oxygenated compounds is the 75% needle 25% twig mixture, which appears to be the most suitable proportion of plant material for pine oil production from P. brutia. Key Word Index Pinus brutia, Pinaceae, essential oil composition, α-pinene, β-pinene, δ-3-carene, limonene, germacrene D. 1041-2905/06/0004-0445$14.00/3—© 2006 Allured Publishing Corp. J. Essent. Oil Res., 18, 445-447 (July/August 2006) *Address for correspondence Introduction Pinus brutia grows naturally, abundantly and strictly in the eastern Mediterranean region extending over from Greece to Lebanon and Iraq. The chemical composition of various Pinus species oils have been the subject of numerous studies. How- ever, work has been focused on North American and Western European species and only a restricted number of chemically oriented articles dealt with the oils of Mediterranean pine species. The chemical composition of P. brutia oil (100% twigs or needles) has been evaluated in few places such as Greece, Italy and Morocco (1-5). Studies have pointed out the high β- pinene content of the oil of P. brutia that characterizes it with respect to other species (1,2,4,6-9). This study investigates the variation of the oils from 00, 25, 50, 75 and 100% w/w needles to terminal twigs of P. brutia in Lebanon with respect to the yield and chemical composition. Experimental Plant material and oil isolation: Twenty five mature samples of P. brutia were randomly collected from a natural population located in Deir-Nbouh, North of Lebanon. Voucher specimens were identified as Pinus brutia following taxonomic verification with Herbarium specimens in the Post Herbarium the American University of Beirut, Lebanon. Information provided by the Ministry of Agriculture indicated that the age of the stand was about 30 years. An estimate of the size of the selected trees was made by measuring the DBH (diameter at breast height) that ranged from 10.8 to 25.5 cm. Needle and twig samples were taken primarily form current year flushes. Since all samples were collected in July, the effect of seasonal variation was eliminated. Ten randomly chosen samples were selected for this study. Indoor air drying of the plant material and later cutting into pieces was realized after the separation of the needles and the terminal twigs. For each sample, five different percent compositions zero, 25, 50, 75 and 100% w/w needles to terminal twigs (designated zero, 25, 50, 75 and 100% needles (% n.)) of the raw material resulted in a total of 50 distillations. Steam distillation for 3h gave pure oil samples for which physical and chemical properties were determined. As the % needles increased from 0 - 100%, the average % yield (%v/w) decreased by 28.0%, from 0.68% ±0.17 to 0.49% ±0.13. The sharpest decline detected in the average yield variation (13.82%) was observed in the range from 25 – 50% needles as compared to 11.07% from 75 to 100% needles. Chemical Analysis Analytical GC was carried out using a Hewlett-Packard 4890 gas-chromatograph equipped with an HP-5 capillary column (15.0 m x 530 μm, 1.5 µm film thickness). Nitrogen