Chemical Composition of the Essential Oil of Artemisia herba-alba Asso Grown in Algeria

Journal of Essential Oil Research: JEOR, Nov/Dec 2006 by Dob, Tahar, Benabdelkader, Tarek

Abstract

The essential oil obtained by hydrodistillation from the aerial parts of Artemisia herba-alba Asso growing wild in M'sila-Algeria, was investigated using both capillary GC and GC/MS techniques. The oil yield was 1.02% based on dry weight. Sixty-eight components amounting to 94.7% of the oil were identified, 33 of them being reported for the first time in Algerian A. herba-alba oil and 21 of these components have not been previously reported in A. herba-alba oils. The oil contained camphor (19.4%), trans-pinocarveol (16.9%), chrysanthenone (15.8%) and β-thujone (15%) as major components. Monoterpenoids are the main components (86.1%), and the irregular monoterpenes fraction represented a 3.1% yield.

Key Word Index

Artemisia herba-alba, Asteraceae, essential oil composition, camphor, trans-pinocarveol, chrysanthenone, β-thujone.

Introduction

The family Asteraceae comprises many aromatic and medicinal plants. Some important genera are Artemisia, Santolina, Centaurea, Chrysanthemum, etc. The genus Artemisia belongs to the tribe Anthemideae which is one of the largest of the Asteraceae family and contains more than 300 species of small herbs and shrubs (1). They are widespread all over the world from which Artemisia herba-alba Asso is one of the 11 spontaneous Artemisia species recorded in Algeria (2). Artemisia herba-alba is extensively used since ancient times as folk remedies by the local population against a wide range of ailments (3).

Artemisia herba-alba is a greenish-silver perennial dwarf shrub growing in arid and semiarid climates and muddy areas. It is known as desert wormwood (Eng.), armoise blanche (Fr.) and chih (Arab), and it is characteristic of the steppes and deserts of the Middle East (Egypt, desert of Israel and Sinai), North Africa (Morocco, Algeria), Spain, extending into Northwestern Himalayas (4).

Over the last 30 years, this species has been extensively studied. Previous investigation on the non volatile constituents of A. herba-alba revealed the presence of sesquiterpene lactones (5,6) and flavonoids (7,8) in the aerial parts. Numerous studies in the literature have reported the composition of A. herba-alba essential oils from different parts of the world (4,9-21). Antibacterial and antileishmanian properties have been reported for this oil (22,23).

As a part of our investigation on aromatic medicinal plants from Algeria, the aim of this work is to provide more information on the composition of the aerial parts oil obtained from naturally grown A. herba-alba, originated from M sila (Algeria), and compare it with other A. herba-alba oils from different localities.

Experimental

Plant material: Aerial parts (leaves, stems) of A. herba-alba were harvested in April 2001 at Djebel Messâd near M'sila (300 Km South Eastern of Algiers capital of the country. Coordinates: UTM: FV35; Latitude: 35° 42' 21"; longitude: 4° 32' 31" ; elevation: 475 m). Plant identification was carried out by A. Beloued, botanist in Agronomic National Institute, Algiers-Algeria, where voucher specimens [HNAI / FA / N°: P48] have been deposited in the Herbarium.

Oil isolation: Aerial parts of A. herba-alba were shadedried (21 days) at room temperature with ventilation, minced and immediately hydrodistilled (100 g) for 3 h using a modified Clevenger-type apparatus. The oil was extracted from the distillate with diethyl ether and then dried over anhydrous sodium sulfate. After filtration, the solvent was removed by distillation under reduced pressure in a rotary evaporator at 30°C and the pure oil kept at 4°C in the dark, until the moment of analysis.

Gas chromatography analysis: The isolated oil was diluted with pentane, and 0.2 µL was sampled for the gas chromatographic analysis. A Chrompack CP 9002 gas chromatograph equipped with an apolar DB-1 fused silica capillary column (30 m z 0.25 mm, film thickness 0.25 µm) was used. Operating conditions: oven temperature program from 50°C (10 min) to 260°C at 2°C/min; "split mode" ratio 1:20; carrier gas N^sub 2^, flow rate 1 mL/min; injector and flam ionisation detector (FID) were heated at 250°C and 26°0C, respectively.

Gas chromatography/mass spectrometry analysis: GC/MS analyses were performed on a Shimadzu capillary gas chromatograph directly coupled to the mass spectrometer system (model GC-17A/SM-QP500). A DB-1 fused silica capillary column (30 m x 0.25 mm, 0.25 µm film thickness) was used under the following conditions: oven temperature program from 50°C (10 min) to 250°C at 2°C/min; injector temperature, 250°C; carrier gas He, flow rate 1 mL/min; injected volume 0.2 µL; ionization energy 70 eV, in the EI mode; ion source temperature 250°C; scan mass range of m/z 35-400.

Components identification: The retention indices (RI) were calculated by comparing the retention times of the eluting peaks with those of the C5-C28 n-alkanes using the van den Dool and Kratz formula (24). Identification of the components was done by GC and GC/MS. The fragmentation patterns of mass spectra were compared with those stored in the spectrometric electronic library (NIST) and with those reported in the literature (25-28). The concentration of the components was electronically calculated from the GC peak areas without the use of correction factors.