Chemical Composition of the Essential Oils of Pistacia atlantica Desf.

Abstract

The chemical composition of the three essential oils obtained by hydrodistillation of the resin, leaves and fruits of Pistacia atlantica Desf. (Anacardiaceae) was studied by GC and GC/MS. Monoterpene hydrocarbons constituted the main chemical group in the resin oil, with α-pinene (42.9%) and β-pinene (13.2%) as the major components. Oil of the fruits contained high amounts of oxygenated monoterpenes, with bornyl acetate (21.5%) as the major component, while oxygenated monoterpenes and sesquiterpenes were found to predominate in the oil of leaves among which terpinen-4-ol (21.7%) and elemol (20.0%) were the most abundant components.

Key Word Index

Pistacia atlantica, Anacardiaceae, essential oil composition, α-pinene, β-pinene, bornyl acetate, terpinen-4-ol, elemol.

Introduction

The genus Pistacia (Anacardiaceae) is widely distributedin the Mediterranean area (1). Pistacia atlantica Desf. is a tree located in north Africa, which can reach 25 m in height and grows in arid and semi-arid areas (2). Pistacia atlantica is valued because it is the source of mastic gum, an exudate which strengthens gums, deodorizes breath, combats coughs, chills and stomach diseases (3). Moreover, the gall of P. atlantica is used as an embalming gradient by rural habitants. Several studies have been carried out on the chemical composition of different parts of P. lentiscus from different areas (4-13) and other varieties, such as P. terebinthus (14), P. chemists Bunge andP khinjink Stock in Egypt (15). However, up to now, no studies have been reported in the literature concerning the chemical composition of P. atlantica Desf. This study was undertaken by GC and GC/ MS analyses to determine the oil composition of different parts of P. atlantica Desf.

Experimental

Plant material: The resin, fruits and leaves of P. atlantica Desf. were collected in July 2000 in the haut atlas (Marrakech region, Morocco). The botanical identification was achieved by the National Scientific Institute (Rabat) where voucher specimens were deposited in the Herbarium.

Isolation procedure: Air-dried samples of leaves, fruits and resin were separately subjected to hydrodistillation for 6 h using a Clevenger-type apparatus. These oils were dried over anhydrous sodium sulfate and kept under nitrogen in a freezer until analysis. The yields obtained were 32.6% (w/w) for the resin, 0.8% (w/w) for the fruits and 0.2% (w/w) for the leaves.

GC/MS analysis: Analyses were carried out in a HewlettPackard 5890 Chromatograph connected to a Hewlett-Packard 5988A mass spectrometer using an ionization voltage of 70 eV The GC conditions were: a) Innowax capillary column (50 m × 0.2 mm); He 25 µl/min the injection and detector heater temperature were 250°C and 280°C, respectively; temperature program from 50°-210°C at 2°C/min); b) HP-I methyl silicone capillary column (25 m × 0.2 mm); He 25 µl/min the injection and detectorheater temperature were 250°C and280°C, respectively; temperature program from 50°-220°C at 2°C/min.

GC analysis: Quantitative Chromatographie analysis were carried out on a Hewlett Packard 5890 Chromatograph equipped with a flame ionization detector (FID ) and coupled to an integrator HP-3390A. The columns and the experimental conditions were the same as those described above, except that the detector heater temperature was 300°C and the inlet head was 20 psi in both cases. The percentage compositions were computed from the GC peak areas without correction factors.

Identification of components: The identification of every component was achieved by comparing their mass spectra with those reported in MS compilations (16,17) and with standards.

Results and Discussion

The results of the GC and GC/MS analyses of the oils led to the identification of the majority of the components, which are listed in the Table I along with their quantitative data and their retention indices. Seventy different compounds, which accounted for about 74% (fruits), 83% (leaves) and 89 % (resin) of the oils from P. atlantica, were identified.

The gas chromatogram pattern was very different in the three oils. The chemical composition of the resin oil contained mainly monoterpene hydrocarbons, with a-pinene (42.9%) and β-pinene (13.2%) as the main compounds. The oil of the fruits also showed high percentages of some monoterpene hydrocarbons such as a-pinene (3.8%), but in general it was the oxygenated monoterpenes that reached maximum levels in the oil with bomyl acetate (21.5%) as the most predominate constituent. In contrast to both oils of resin and fruits, it can be seen that the leaf oil showed a high percentage of sesquiterpene compounds (41.1%), with elemol (20.0%) and β-eudesmol (8.4%) as major components. Finally, it is interesting to note that a-pinene, the main compound in resin oil, was found only in low amount (0.9%) in the leaf oil.

Summarizing our results, the following conclusions can be drawn: The resin is rich in oil (32.6%) and it contained mainly monoterpene hydrocarbons. The oil of the fruits was determined to be rich in oxygenated monoterpenes. Finally, the leaf oil was chemically different from the other oils because of its high percentage of sesquiterpene compounds.