[P-072]
ESSENTIAL OIL OF Thymus atticus ÈELAK.

Olga TZAKOU1 and Theophanis CONSTANTINIDIS2
1Department of Pharmacognosy, School of Pharmacy, University of Athens, Athens 15771, Greece
2Institute of Botany, Department of Biology, University of Patras, Gr-26500, Patras

ABSTRACT

The essential oils of Thymus atticus Èelak (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%).


INTRODUCTION

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 Èelak.

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.


MATERIALS AND METHODS

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).


RESULTS AND DISCUSSION

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.


Table 1. Chemical Composition (%) of the essential oil of Thymus atticus Èelak. Mt Parnitha
Compound
RI
Sample A
Sample B
Tricyclene
905
0.23
1.06
a-Thujene
912
0.41
0.19
a-Pinene
921
9.17
7.19
Camphene
935
4.08
4.94
Thuja-2,4(10)-diene
939
0.23
0.14
Sabinene
959
0.34
0.99
b-Pinene
963
1.15
2.25
b-Myrcene
980
11.01
6.90
3-Octanol
989
tr
tr
a-Phellandrene
993
0.19
0.22
d-3-Carene
1006
-
tr
a-Terpinene
1006
1.13
0.57
o-Cymene
1016
6.31
-
p-Cymene
1016
1.80
2.45
1,8-Cineole
1023
4.65
11.04
(Z)-b-Ocimene
1026
0.15
0.56
(E)-b-Ocimene
1037
1.47
3.98
g-Terpinene
1046
2.80
1.19
cis-Sabinene hydrate
1054
-
0.09
Octanol
1060
-
tr
cis-Linalool oxide
1066
-
tr
Terpinolene
1075
0.49
0.52
Linalool
1091
1.18
4.15
Nonanal
1093
0.11
0.24
a-Thujone
1094
tr
-
1-Octen-3-yl acetate
1101
-
0.10
b-Thujone
1105
tr
-
cis-p-2-Menthen-1-ol
1112
-
tr
a-Campholenal
1114
0.26
0.38
trans-Pinocarveol
1128
0.32
tr
cis-Verbenol
1131
-
tr
Camphor
1134
1.82
4.19
Benzene-1-ethenyl-4-methoxy
1139
0.20
0.16
Pinocarvone
1154
tr
-
Borneol
1157
2.80
5.55
Terpin-4-ol
1166
1.38
1.51
p-Cymen-8-ol
1175
tr
-
a-Terpineol
1180
0.63
1.83
Myrtenol
1184
0.35
0.39
Decanal
1192
tr
0.16
Verbenone
1196
-
tr
trans-Carveol
1206
-
0.29
Nerol
1215
-
0.35
Isobornyl formate
1209
0.34
-
Cumin aldehyde
1221
tr
-
Carvacrol methyl ether
1225
0.24
-
Carvotanacetone
1230
-
0.17
Linalool acetate
1244
0.43
1.79
Bornyl acetate
1273
0.30
0.56
Thymol
1276
3.97
tr
Carvacrol
1290
7.08
0.22
a-Cubebene
1330
0.25
tr
Thymol acetate
1336
0.55
-
Neryl acetate
1351
tr
0.31
Carvacrol acetate
1354
2.46
-
a-Copaene
1362
2.39
1.71
b-Bourbonene
1370
0.90
1.23
b-Cubebene
1374
0.29
0.21
b-Elemene
1377
tr
tr
(E)-Caryophyllene
1407
4.83
6.22
b-Gurjunene
1413
tr
1.32
a-Humulene
1437
0.26
0.48
allo-Aromadendrene
1444
0.38
0.43
g-Muurolene
1467
2.26
2.19
Bicyclogermacrene
1481
1.11
1.05
a-Muurolene
1488
-
tr
b-Bisabolene
1493
4.90
0.93
g-Cadinene
1498
tr
0.21
d-Cadinene
1508
1.73
1.04
Geranyl n-butyrate
1540
0.33
-
b-Calacorene
1551
tr
-
(E)-Nerolidol
1553
0.71
0.72
Spathulenol
1556
1.17
-
Caryophyllene oxide
1572
4.45
8.58
Viridiflorol
1578
0.37
1.21
b-Oplopenone
1594
-
0.35
1-epi-Cubenol
1612
0.20
0.16
epi-a-Muurolol
1627
-
0.47
Cubenol
1622
tr
-
b-Muurolol
1625
tr
0.15
b-Cadinol
1640
0.18
0.67
14-Hydroxy-9-epi-(E)-caryophyllene
1650
0.38
-
Cadalene
1653
tr
-
Cembrene
1927
0.38
tr
Total  
97.50
95.96
t=trace<0.01%

LITERATURE
  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, 46th Annual Congress of the Society for Medicinal Plant Research, August 31st-September 4th, 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.

[P-072]