Chemical Composition of the Essential Oil of Micromeria libanotica Boiss., an Endemic Species of Lebanon

Journal of Essential Oil Research: JEOR, Jul/Aug 2005 by Diab, Youssef, Auezova, Lizette, Chebib, Hanna, Chalchat, Jean-Claude

Abstract

The essential oil obtained by steam distillation from Micromeria libanotica growing wild in the cedar mountains of Lebanon, was examined by GC and GC/MS. Twenty-five components, representing about 83% of the oil were identified. The major constituents of the oil were found to be the monoterpene ketones isomenthone (44.5%), pulegone (13.5%) and isopulegone (6.5%).

Key Word Index

Micromeria libanotica, Labiatae, essential oil composition, isomenthone, pulegone.

Plant Name

Micromeria libanotica Boiss.

Source

The plant was collected in September 1998, at late flowering stage, from the Cedar Mountain region of Lebanon (-1800 m above sea level), near the village of Becharri. A voucher specimen has been deposited at the Chemistry Department of the Faculty of Science-2, Fanar, Lebanese University.

Plant Part

The leaves and twigs were air-dried and submitted to steam distillation to produce a colorless oil in a 1.1% yield as moisture free basis.

Previous Work

Micromeria libanotica is a plant endemic to the high mountains of Lebanon, where it is still widely used in popular medicine as an effective anti-cough herbal drink. No previous work on the chemical composition of its oil has been reported. oils from other species of Micromeria have been studied (1-8). The composition of M. libanotica is very different compared to those of other Micromeria species, except some similarities with M. dolichodontha (9).

Present Work

The oil of the M. libanotica was analyzed by capillary GC and GC/MS. The GC analysis was performed on a DELSI121C chromatograph (FID) with a fused silica M7COT capillary column (25 m x 0.25 mm, film thickness 0.25 �m) and CP Wax 52 CB stationary phase. The temperature was programmed from 50�C with 5 min initial hold and then 50�-210�C at 2�C/min, using N^sub 2^ as the carrier gas (spleet 60 mL/min).

GC/MS analysis was performed on a Hewlett Packard with a fused silica WCOT capillary column (50 m x 0.25 mm, film thickness 0.25 �m) CP wax 51, temperature programmed from 50�-230�C at 3�C/min using He as the carrier gas. The oil components were identified by comparing the retention indices of standard substances with those present in the mixture and confirming by mass spectroscopy (10,11). Results of the analysis (Table I) showed that the oil of M. libanotica was dominated by the monoterpene skeleton ofp-menthane, which accounted for 78.2% of the oil.

Acknowledgments

The authors are indebted to C. Abouchaarforbotanicalidentification and to Lebanese CNRS for financial support.

References

1. K.H.C. Baser, B.DemircakmakandH.Duman, Composition of the essential oil ofMicromeria cremnophila Boiss. et Helder. subsp. amana (Rech.fil) P.M. Daw's. J. Essenl. oil Res., 9, 725-726 (1997).

2. G.R. Mallavarapu, S. Ramesh and K. Subrahmanyam, Composition of the essential oil Micromeria biflora. J. Essent. oil Res., 9, 23-26 (1997).

3. K.H.C. Baser, N.Kirimer,T.OzekandG.Tumen, Essentila oil of Micromeria carminea P.H. Davis. J. Essent. oil Res., 4, 457-458 (1995).

4. U. Ravid, E. Putievsky and I. Katzir, Chiral GC analysis of menthone and isomenthone with high enantiomeric purities in laboratory made and commercial essential oils. Flav. Fragr. J., 9, 139-142 (1994).

5. N. Kirimer, G. Tumen, T. Ozek and K.H.C. Baser, The essential oil of Micromeria fructicosa (L.) Druce subsp. barbata (Boiss. Kotschy) RH. Davis of Turkish origin. J. Essent. oil Res., 5, 79-80 (1993).

6. T. Ozek, N. Kirimer and K.H.C. Baser, Composition of the essential oil of Micromeria myrtifolia Boiss.et Hohen. J. Essent. oil Res., 4, 79-80 (1992).

7. S.S.EI-Hawary, M.A. Al-Yahya, I.A.AI-Meshal. J.S. Mossa and M.S. Hifnawy, Aromatic plants of Saudi Arabia - part 13, Essential oil of Micromeria synaica. Int. J. Pharmacogn., 29, 193-196 (1991).

8. N. Kirimer, T. Ozek and K.H.C. Baser, Composition of the essential oil of Micromeria congesta. J. Essent. oil Res., 3, 387-393 (1991 ).

9. K.H.C. Baser, N. Kirimer and H. Duman, Composition of the essential oil of Micromeria dolichodontha RH. Daw's. Flav. Fragr. J., 12, 289-291 (1997).

10. RW. McLafferty and D.B. Stauffer, Wiley/NBS, Registry of mass spectral data,. Wiley-lnterscience, New York (1989).

11. P.P. Adams, Identification of essential oil components by gas chromatrography flash mass spectroscopy. Allured Publishing Corporation, Carol Stream, IL (1995).

Youssef Diab,* Lizette Auezova and Hanna Chebib

D�partement de Chimie, Facult� des Sciences-2, Universit� Libanaise Fanar, Jdaidet el Matn, BP (90656), Lebanon

Jean-Claude Chalchat

Laboratoire de Chimie des Huiles Essentielles, Universit� Biaise Pascal de Clermont, Campus des C�zeaux, 63177 Aubi�re Cedex, France

* Address for correspondence

Received: May 2002

Revised: August 2002

Accepted: September 2002

10410 -2905/05/00040 -0449$6.00/00 -� 2005 Allured Publishing Corp.