Essential Oil Composition of Pinus halepensis Mill. from Three Different Regions of Algeria

Journal of Essential Oil Research: JEOR, Jan/Feb 2007 by Dob, Tahar, Berramdane, Tayeb, Chelghoum, Chaabane

Abstract

Needles of Pinus halepensis Mill. were collected from three different locations at Sidi Feradj (SF), Djelfa (Dj) and Saïda (Sd) in Algeria. Their oils isolated by hydrodistillation yielding 0.5% from SF, 0.8% from Dj and 0.9% from Sd, have been investigated for their components by means of GC and GC/MS techniques. More then 41 compounds were identified in the needle oils of Sidi Feradj (SF) and Saïda (Sd) and 39 compounds in Djelfa (Dj). The main constituents of three samples of P. halepensis leaf oil were β-caryophyllene (19.8-25.8%), followed by α-humulene (6.2%) in SF and 10.5% in Sd and aromadendrene (8.5%) in Dj, while the third constituents were aromadendrene (4.2%) in SF and α-pinene (5.2%) in Dj and 6.4% in Sd.

Key Word Index

Pinus halepensis, Pinaceae, Aleppo pine, essential oil composition, β-caryophyllene, α-humulene.

Introduction

The genus Pinus belongs to Pinaceae family comprising about 250 species (1). The group Halepensis comprises two major species: Pinus halepensis (Aleppo pine) and Pinus brutia (Brutia pine). Morphological and anatomical studies showed that they are distinguished by numerous trials (2,3). Pine is widely used in traditional therapeutic and pharmaceutical practice in the world (4,5). A large part of the phytochemical analysis of Pinus species is due to the presence of essential oils (6-12), flavonoids ( 13) and alkaloids ( 14). Several phytochemical analyses of P. halepensis have already been published on the essential oils (15-20), terpenes (21-26), turpentine (27) and phenolic compounds (28).

In this paper we describe the chemical composition of the leaf oils of P. halepensis harvested from three different regions of Algeria. Also, we compare with the oils produced by other P. halepensis grown in different geographical regions in the world.

Experimental

Plant material and oil isolation: The needles of P. halepensis Mill, were collected in summer 2002, from three Algerian provenances Sidi Feradj (SF), Djelfa (Dj) and Saïda (Sd). The analyzed needles were collected from one tree from every provenance. Table I summarizes geographic location and diverse environmental conditions of these provenances. Botanical identification has been carried out in the botanical department of the National Agronomic Institute of Algiers (Algeria), where a voucher specimen [HNAI / FA / N°: P105] of the plants has been lodged in the Herbarium of this institute. The oils were isolated by hydrodistillation using a Clevenger-type apparatus from the air-dried cut needles, yielding 0.5% in SF, 0.8% in Dj and 0.9% in Sd. The three oils were dried over anhydrous sodium sulfate and stored at 4°C in the dark prior to analysis.

Analysis: The GC analyses were accomplished using a ChrompackCP 9002 equipped with DB-I fused silica capillary columns (30 m x 0.32 mm, 0.25 µm film thickness), working with the following temperature program: 50°C for 3 min then 2°C/min to 260°C for 5 min; FID detector heaters 280°C; injector heaters 250°C; nitrogen was used as carrier gas at a flow rate 1 mL/min in the split mode (1:50), with an injection vol. 0.2 µL

GC/MS analysis was performed on a Trace MS Finnigan chromatograph equipped with a DB-I capillary column (30 m x 0.32 mm, 0.25 µm film thickness). It was programmed from 50°C (3 min) to 260°C (5 min) at 2°C/min with He carrier gas at a flow rate of 1 mL/min and injector heater 250°C. The massspectrometer was operating (full scan-mode) in the El-mode at 70 eV. The ion source temperature was 200°C.

Identification of components: In order to determine retentions indices (RI) a series of n-alkanes (C^sub 5^-C^sub 28^) mixture was analyzed under the same operative conditions on DB-1 columns and the retention indices were calculated following Van den Dool and Kratz (29). The identification of components was based on their retentions indices on non-polar (DB-1) column and by computerized matching of the acquired mass spectra with those stored in the spectrometer data base using NIST mass spectral library and with the literature (12,20,30).

Results and Discussion

The identified compounds, their percentage composition and their retentions indices from the three needle oil samples of wild-growing Aleppo pine collected in three different locations (SF, Dj and Sd) are arranged in order of their elution on the DB-1 column and summarized in Table II.

Forty-one compounds have identified in the oils of SF and Sd and 39 constituents from Dj regions.

A comparative study from three populations of the oils of P. halepemis (SF, Dj, Sd) was carried out and the yield oil was 0.5%, 0.8% and 0.9%, respectively. Although, the major identified compounds in the three analyzed oils were mono- and sesquiterpenoid hydrocarbons, their qualitative and quantitative composition differed considerably.

The monoterpene hydrocarbons were found in low concentrations in the oils of three regions, with Sd (20.7%) being the highest, followed by Dj (17.2%) and SF (3.8%). The content of this fraction included α-pinene as the major monoterpenoid hydrocarbon; 5.2% in Dj and 6.4% in Sd, whereas in the SF region it was 0.7%. δ-3-Carene could not found in the oil from the Dj region. Substantial differences in the oxygenated monoterpenes were also observed in the three samples (5.5%, 2.1% and 2.1% in the oils from Dj, SF and Sd regions, respectively). α-Pinene oxide (3.0%) and borneol (1.2%) were the main oxygenated monoterpenes found in oils from the Dj and SF regions, respectively.