Institute of Forenzic Sciences, Faculty of Medicine, University of Novi Sad, ... Vis. ex Bentham, collected from Montenegro, was analyzed by GC and GC/MS.
T.18, bracteosus J. Essent. Oil Res., XXX-XXX (May/June 2006)
Chemical Composition of the Essential Oil of the Species Thymus bracteosus Vis. ex Bentham (Lamiaceae) Violeta N. Slavkovska, Branislava S. Lakušić* and Radiša B. Jančić Institute of Botany, Faculty of Pharmacy, University of Belgrade, Vojvode Stepe 450, 11000 Belgrade, Serbia and Montenegro
Neda A. Mimica-Dukić Institute of Chemistry, Faculty of Natural Sciences, University of Novi Sad, Trg Dositeja Obradovića 3, Novi Sad, Serbia and Montenegro
Djordje S. Vujičić Institute of Forenzic Sciences, Faculty of Medicine, University of Novi Sad, Hajduk Veljkova 1, Novi Sad, Serbia and Montenegro Abstract
The oil composition of Thymus bracteosus Vis. ex Bentham, collected from Montenegro, was analyzed by GC and GC/MS. The oil yield was 0.15%. Twenty-seven components were identified. Terpene hydrocarbons were dominant in the oil (68.5%). The main constituents of the oil were: germacrene D (15.5%), β-caryophyllene (14.6%), p-cymene (10.2%) and α-pinene (7.2%). Key Word Index Thymus bracteosus, Lamiaceae, essential oil composition, germacrene D, β-caryophyllene, p-cymene.
Introduction Genus Thymus L. belongs to the family Lamiaceae, subfamily Nepetoideae (1), and includes about 150 species spread in arid, temperate and cold regions of the Old World, north of the Equator up to the shores of Greenland. The western Mediterranean region seems to be the origin of this genus (2). There are 66 known species in the flora of Europe, about 50% of which are endemic (3). The flora of Serbia contains 30 species, a large number of which are endemic (4). The species of genus Thymus are well known as medicinal plants because they contain tannins, bitter substances, and flavonoids, and are aromatic because of their essential oil content (2). These species are used for medical purposes, due to their antiseptic, antispasmodic and antitussive properties. Genus Thymus is a taxonomically complex group of plants. It is divided into eight sections, and the sections are divided into subsections based on the morphological similarities and phylogenetic relationships between the species (5). Thymus bracteosus Vis. ex Benth. is endemic in the western part of Montenegro (3) and belongs to section Hyphodromi and subsection Serpyllastrum (5). To our knowledge, no chemical studies of T. bracteosus
have been previously reported and the aim of this work is to investigate the quantity and composition of the oil of this endemic species.
Experimental Collection of plant material: The plant material for investigation was collected on Mount Orjen (Montenegro), on Prčanj locality (900 m a.s.l.), N.E. exposition, inclination 15°, in July 2003. The voucher specimen is kept at the Institute of Botany Herbarium, Faculty of Pharmacy, University of Belgrade. Oil isolation procedure: The aerial parts of the plant were dried at room temperature and hydrodistillated (100 g) for 3 h using a Clevenger-type apparatus (6). The oil was collected in hexane. The oil obtained had a yield of 0.15%. GC: The GC analysis of the oil was carried out on a GC HP-5890 II apparatus, equipped with the split-splitless injector, attached toHP-5 fused silica capillary column (25 m x 0.32 mm, 0.52 µm film thickness) and fitted to FID detector. Quantitative data were obtained from FID area measurements without the use of correction factors. Received: May 2004
*Address for correspondence
Revised: July 2004 1041-2905/06/0003-000X$14.00/0—© 2006 Allured Publishing Corp. Vol. 18, May/June 2006
Accepted: November 2004 Journal of Essential Oil Research/
Slavkovska et al.
Table I. Chemical composition (%) of Thymus bracteosus oil Component α-pinene camphene β-pinene myrcene δ-3-carene α-terpinene p-cymene (Z)-β-ocimene γ-terpinene linalool camphor borneol terpinen-4-ol pulegone bornyl acetate α-cubebene α-copaene β-bourbonene β-caryophyllene (Ε)-β-farnesene germacrene D β-gurjunene δ-cadinene α-cadinene caryophyllene oxide salvial-4(14)-en-1-one α-cadinol Total:
Percentage 7.2 1.5 0.8 3.8 0.1 0.1 10.2 0.2 0.9 1.1 1.9 1.3 0.7 0.5 0.2 0.1 0.4 4.7 14.6 5.0 15.5 1.5 1.8 0.1 4.8 0.5 4.4 83.9
The injector temperature was 250ºC and the detector temperature 280ºC. The temperature programs were 50ºC (1 min), 50º – 100ºC at the rate 5ºC/min, 100º – 200ºC at the rate of 9ºC/min and over 200ºC, 25 min. The carrier gas was He, 0.8 mL/min constant flow. Detector parameters: solvent delay 5 min. GC/MS: The same analytical conditions were employed for GC/MS analysis, where HP-G 1800 A, GCD system was used. MS were taken at 70 eV. The mass range was 45 – 425 m/z (capillary column HP 5-MS, (30 m x 0.25 mm, film thickness 0.25 µm). Component identification and qualitative estimation: Identification of individual constituents was made by comparison of their retention times with those of analytical standards of available terpenoids, and by computer searching, matching mass spectral data with those held in MS library (7).
monoterpenes: 5.7%), while the quantity of sesquiterpene compounds was larger—53.4% (hydrocarbons 43.7%, oxygenated sesquiterpenes 9.7%). Terpene hydrocarbons were dominant (68.5%). The main constituents of the oil were: germacrene D (15.5%), β-caryophyllene (14.6%), p-cymene (10.2%) and α-pinene (7.2%). Oxygenated terpenes were determined in the quantity of 15.4%. According to literature data (8,9), other species of the subsection Serpyllastrum differ from T. bracteosus in both quantity and composition of the oil. Species T. zygioides Griseb. had 0.6% of oil, which consisted mostly of oxygenated terpenes (67.1%), dominated by thymol (24.6%), linalool (12.2%), borneol (8.7%) and 1,8 cineole (7.2%). Terpene hydrocarbons were also determined in the oil in the quantity of 23.6% (8). Species T. leptophyllus Lange was found to contain 0.8% oil dominated by oxygenated terpenes (91.6%), among which linalyl acetate (68.5%) and linalool (17%) were major, while terpene hydrocarbons were minor constituents (3.8%) (9). The oil of T. bracteosus differed from other species of section Hyphodromi. T. cilicicus Boiss. et Ball. and T. sipyleus Boiss. belong to subsection Thymbropsis. These species contained 1.5% and 1.2% of oil, respectively. Oxygenated terpenes (74.0%) dominated the oil of T. cilicicus with the following main components: α-terpineol (33.4%), camphor (8.4%), citronellol (6.5%) and linalool (5.9%). Terpene hydrocarbons were determined in the quantity of 11.2%. Oxygenated terpenes (72.4 %) were dominant in T. sipyleus oil with geranial (32.8%), α-terpineol (7.3%), neral (7.2%) and isoborneol (7.1%) dominating while monoterpene hydrocarbons content was 8.8% (8). Acknowledgments
The authors are grateful for financial support by Ministry for Science, Technology and Development of Serbia (Project No. 1568). References
1. 2. 3.
4. 5.
Results and Discussion The leaves, bracts, stems and flowers of T. bracteosus were covered with a large number of secretory structures, but they contained only a small quantity of oil, 0.15%. The chemical composition of the oil is presented in Table I. The identified compounds (27 components) amounted to 83.9% of the whole oil. Monoterpene compounds were determined in the quantity of 30.5% (hydrocarbons: 24.8%, oxygenated
/Journal of Essential Oil Research
6. 7. 8. 9.
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