Volatile Constituents of the Essential Oil of Ajuga chamaepitys (L.) Schreber. ssp. chamaepitys from Spain

Velasco-Negueruela, Arturo

Abstract

The chemical composition of the essential oil extracted from the aerial parts of Ajuga chamaepitys (L.) Schreber ssp. chamaepitys has been studied by GC and GC/MS. Thirty-six compounds were identified and [gamma]-muurolene (40.3%), limonene (20.5%) and germacrene B (7.8%) were found to be the major constituents of the oil.

Key Word Index

Ajuga chamaepitys ssp. chamaepitys, Lamiaceae, essential oil composition, [gamma]-muurolene, limonene, germacrene B.

Introduction

Ajuga L. belongs to the Lamiaceae family and is represented in Europe by 10 species and four subspecies. Ajuga chamaepitys (L.) Schreb. subsp. chamaepitys inhabits west and central Europe and Italy (1). In addition, it has been used as a flavoring substance. Some biologically active components (ajugalactone, ajugapitin, chamaepitin) have been reported before (2). In Spain this species is known as "pinillo oloroso" (odor pine).

The oils of A. chamaepitys (Schreber) Archangeli ssp. chia have been previously published. Mericli et al. (3) studied the aerial parts of A. chamaepitys subsp chia var. chia extracted with petroleum ether, ethanol and by hydrodistillation. Caryophyllene (24.4%) and [beta]-citronellol (10.7%) were characterized as major constituents of the oil.

Baser et al. (4) analyzed the chemical composition of A. chamaepitys subsp. chia var. chia and var. ciliata. Sixty-five compounds were identified in A. chamaepitys subsp. chia var. chia, with [beta]-pinene (20.8%) and germacrene D (12.6%) being the major constituents. Twenty-nine compounds were identified in A. chamaepitys subsp. chia var. ciliata; germacrene D (14.6%) and [beta]-pinene (14.0%) being the main ones.

In the present work we reported on the chemical composition of the oil of Ajuga chamaepitys subsp. chamaepitys gathered in Spain. As far as we know the oil composition of this species has not been previously reported.

Experimental

Plant material: Aerial parts of A. chamaepitys subsp. chamaepitys were gathered at flowering stage in Morata de Tajuna, Madrid (Spain), in May 2000. A voucher specimen was deposited at the Herbarium of the Faculty of Biology, Complutense University, Madrid, Spain.

Analysis: Plant material was hydrodistilled in a Clevenger-type apparatus according to the method recommended in the Spanish Pharmacopoeia (5). The oils were dried over anhydrous sodium sulfate and stored at 4°C in the dark. The yield was 0.1% based on dried weight of the sample.

GC analysis was carried out on a Varian 3300 gas chromatograph fitted with a fused silica methyl silicone DB-1 column (50 m × 0.25 mm, 0.25 µm film thickness). Temperature was programmed from 95°-240°C at 4°C/min. Injection was performed at 250°C in the split mode (1:100). A flow of 1.5 mL/min carrier gas (N^sub 2^) was used. Detection was performed by FID at 250°C. Injection volume for all samples was 0.1 µL.

GC/MS analyses were carried out on a Hewlet-Packard 5890 gas Chromatograph fitted with a fused Silica SE-30 capillary column (25 m × 0.22 mm, 0.25 µm film thickness), coupled to an HP 5971A mass selective detector. Column temperature was programmed from 70°-220°C at 4°C/min and helium was used as carrier gas. Mass spectra were recorded in the scan mode at 70 eV.

Qualitative analyses: Most constituents were tentatively identified by GC by comparison of their retention indices with those of authentic standards available in the author's laboratory or with retention indices in close agreement with references (6-8). Further identification was achieved by GC/MS. Other constituents were either synthesized or identified in oils of known composition. The fragmentation patterns of mass spectra were compared with those stored in the spectrometer data base using the N B S54K. L and WILEY. L built-in libraries and with those published in the literature (9,10).

Results and Discussion

The identified components from the aerial parts of A. chamaepitys ssp. chamaepitys, their retention indices and their percentage composition are listed in Table I. The constituents were arranged in order of elution on DB-I column. The amount of sesquiterpenes (63.0%) was higher than that of monoterpenes (36.9%).

[gamma]-Muurolene (40.3%), limonene (20.5%) and germacrene B (7.8%) were found to be the major constituents of the oil. Other minor compounds were identified as [alpha]-pinene (5.6%), bicyclogermacrene (5.1%), [beta]-cubebene (2.9%), camphene (2.7%), (Z)-[beta]-ocimene (2.6%), sabinene (2.5%) and myrcene (1.3%).

We have found that the oil of A. chamaepitys subspecies chamaepitys presented higher amounts of [gamma]-muurolene (40.3%) and limonene (20.5%) while in subspecies chia [beta]-pinene (20.8% and 14.0%) and germacrene D (12.6% and 14.6%) were found as major constituents in the varieties chia and ciliata, respectively. It is worth mentioning that [beta]-pinene and germacrene D have not been detected in our oil, and in the oils of the var. chia and var. ciliata, [gamma]-muurolene and limonene were found in lower amounts.

References

1. T.G. Tutin, V.H. Heywood, N.A. Surges, D.M. Moore, D.M. Valentine, S.M. Walters and D.A. Webb, Flora Europaea. Cambridge University Press, London (1968).

2. M. De Vincenzi, E. Mancini and M.R. Dessi, Monographs on botanical flavouring substances used in food. Part Vl. Fitoterapia, 68,49-61 (1997).

3. F. Mericli, A.M. Mericli, Y. Korkmaz-Alp and F. Yilmaz, Volatile and phenolic compounds of Ajuga chamaepitys subs, chia var. chia. Acta Pharm. Turc., 36, 17-19 (1994).

4. K.H.C. Baser, Z. Erdemgil.T. Ozekand B. Demierci, Composition of the essential oils from two varieties of Ajuga chamaepitys subsp. chia from Turkey. J. Essent. oil Res., 11, 203-205 (1999).

5. RealFarmacopea Espanola, MinisteriodeSanidadyConsumo. Madrid (1997).

6. R.P. Adams, Identification of Essential oils Components by Gas Chromatography/Mass Spectroscopy. Allured Publishing Co., Carol Stream, IL (1995).

7. W. Jennings and T. Shibamoto, Qualitative Analysis of Flavor and Fragrance Volatiles by Capillary Gas Chromatography. Academic Press, New York (1980).

8. A.A. Swigarand P.M. Silverstein, Monoterpenes. Aldrich Chemical Co., Milwakee, Wl (1981).

9. L.M. Libbey, A Paradox data base for GC/MS data on Components of Essential oils and Other Volatiles. J. Essent. oil Res., 3,192-194 (1991 ).

10. D. JoulainandA.W. Konig, The Atlas of Spectral Data of Sesquiterpene Hydrocarbons, E.B.-Verlag ,Hamburg (1998).

Arturo Velasco-Negueruela, M(a) Jose Perez-Alonso, Jesus Pala-Paul* and Ana lnigo

Departamento de Biologin Vegetal I, Facultad de Biologia, Unwersidad Complutense, 28040-Madrid, Spain

Jesus Sanz

Instituto de Quimica Organica, Juan de la Cierva n° 3, 28006-Madrid, Spain

* Address for correspondence

1041-2905/04/0004-0372$6.00/0-© 2004 Allured Publishing Corp.

Received: March 2001

Revised: April 2001

Accepted: May 2001

Copyright Allured Publishing Corporation Jul/Aug 2004
Provided by ProQuest Information and Learning Company. All rights Reserved