The essential oils of Thymus atticus Čelak (Labiatae) collected in December 1997 (sample A) and in June 1998 (sample B) were isolated by hydrodistillation and analyzed by means of GC/MS. The main constituents for sample A were myrcene (11.01%), a-pinene (9.17%) and carvacrol (7.08%), while for sample B were 1,8-cineole (11.04%), caryophyllene oxide (8.58%) and a-pinene (7.19%).

The genus Thymus belongs to the family of the Labiatae, which is divided in 4000 species, classified in 200 genera and 8 sub-families. From the genus Thymus there are about 60 species known in Europe. In thyme plants the production of essential oil is very variable, which is due to two main reasons: the endogenous factors inherent to the genetic constitution and the exogenous factors, dependent on the ecological and environmental conditions in which plant grows. Many phytochemical, ecological and genetic studies of Thymus species have been done and especially for Thymus vulgaris. The existence of different chemotypes in this taxonomically difficult genus is well known and documented (Stahl-Biskup 1991).

In our continuing research on the essential oils of Thymus species (Tzakou et al. 1998, Tzakou and Constantinidis 1998, Tzakou and Constantinidis 1999) we have investigated the essential oil of Thymus atticus Čelak.

In literature we have found only one reference (Tümen et al. 1997)) referring to the oil of Th. atticus. However, this oil was rich in phenolic compounds (44.91%), mainly thymol.

Thymus atticus, a member of Th. sections Hyphodromi (Morales 1997), is pre-dominately a lowland species that occasionally extends to c. 1800 m (Baden 1991). It occurs in the E. half of the Balkan Peninsula and N.W. Turkey. Its diagnostic morphological characters include the creeping and rooting stems, the linear to lanceolate glabrous leaves with flat margins, the broad bracts that do not resemble leaves, the rather long calyx and the white or pale pink corolla.

Thymus atticus is usually found in stony places, calcareous or not, forest clearings, dry stream beds, slopes covered by phrygana or maquis, road cuttings, etc. It starts flowering in May and, depending on altitude and local environmental conditions, its flowering period may prolong to late summer.

Plant material

Wild growing plants of Th. atticus were collected from Mt. Parnes in different growing stages: in December 1997 (sample A) and in June 1998 (sample B). The aerial parts of about 5-7 individuals of each population were combined to give a representative sample. Specimens were identified by Dr. Th. Constantinidis. Voucher specimens have been deposited at the Herbarium of the Institut of Botany, University of Patras (UPA).

Sample analysis

Dried aerial parts from each sample were cut into small pieces just before subjected to hydrodistillation for 3 h using a Clevenger-type apparatus. The obtained yellowish oils were dried over anhydrous sodium sulfate and stored at 4-6°C. The oils were analyzed by GC/MS using a Hewlett Packard 6890/5973 system operating in EI mode, fitted with a HP 5MS capillary column (30m x 0.25mm; 0.25mm film thickness). GC oven initial temperature was 60°C and programmed to 280°C at a rate of 3°C/min. Library search was carried out using Wiley, NIST/NBS MS libraries and from the best match of their mass spectra with those of the literature (Adams 1995).

Eighty-two components were identified from the oils of Th. atticus representing 97.49% and 95.80% of the total oil. The yields of the oils were 0.38% for sample A and 0.69% for sample B. Th. atticus oils contained high quantities of monoterpene hydrocarbons (41.0%, 33.1% respectively) and monoterpene alcohols (28.8%, 32.8% respectively). The sesquiterpene hydrocarbon content was rather similar in the two samples (19.3% and 17%). The oxygenated sesquiterpene fraction was relatively poor in sample A (7.5%), whereas in sample B was 12.3%. The qualitative essential oil composition of the different samples is similar. There are however, quantitative differences.

The highest fluctuations have been found in the amount of the following compounds: o-cymene (6.31%, 0%), 1,8-cineole (4.65%, 11.04%) and carvacrol (7.08%, 0.22%).

The main constituents of the winter sample were myrcene (11.01%), a-pinene (9.17%) and carvacrol (7.08%). In the summer harvested sample the major components were 1,8-cineole (11.04%), caryophyllene oxide (8.58%) and a-pinene (7.19%).

1,8-Cineole ranks fourth in frequency in Thymus essential oils and has a quantitative prevalence in the oil of Th. atticus produced from flowering plants. Myrcene was a quantitatively important aliphatic monoterpene in the winter sample.

1. Adams R.P.(1995): Identification of Essential Oil Components by Gas Chromatography and Mass Spectrometry, Allured Publ.Corp., Carol Stream, IL, USA.

2. Baden C. (1991): Thymus L., pp. 139-165. In Strid A. & Tan K. (eds.), Mountain Flora of Greece vol.2, Edinburgh University Press, Edinburgh.

3. Stahl-Biskup E.(1991): The Chemical Composition of Thymus Oils: A Review of the Literature 1960-1989, J. Essent. Oil Res. 3, p.61-82.

4. Tümen G., Kirimer N., Kürkçüoglu M. and Baser K.H.C.(1997): Composition of the Essential Oils of Thymus atticus and Thymus regneri from Turkey, J. Essent. Oil Res., 9, p. 473-474.

5. Tzakou O., Verykokidou E., Roussis V., Chinou, I. (1998): Chemical Composition and Antibacterial Properties of Thymus longicaulis subsp. chaubardii Oils: Three Chemotypes in the Same Population J. Essent. Oil Res., 10, p. 97-99.

6. Tzakou O., Constantinidis Th.(1998): Essential oil of Thymus parnassiccus Halacsy, 46^th Annual Congress of the Society for Medicinal Plant Research, August 31^st-September 4^th, 1998, Vienna, Austria.

7. Tzakou O., Constantinidis Th.(1999): Karyological Study and Essential Oil Analysis of Thymus teucrioides subsp. candilicus Joint Meeting of the ASP, AFERP, GA and PSE, July 26-30, 1999, Amsterdam, The Netherlands.