Essential oil from Artemisia herba-alba Asso grown wild in Algeria: Variability assessment and comparison with an updated literature survey

1 Introduction

Asteraceae Martinov (= Compositae Giseke) is a family of herbs, shrubs or trees, commonly known as Aster or Compositae family, comprising about 1535 genera and 23,000 species. Artemisia (wormwood, tarragon), one of the most economically important and widespread of this family genus, includes 400 species (Judd et al., 2002).

Dobignard, (1977) has shown the taxonomic complexity of A. herba-alba lato sensu described in North Africa, and the need for a taxonomic study of the whole group. In the present study we followed the traditional criterion of this species delimitation. Eleven spontaneous Artemisia species are present in the Algerian flora (Quezel and Santa 1963). Artemisia herba-alba Asso = [Artemisia aragonensis Lam., Seriphidium herba-alba (Asso) Soják] (Greuter, 2006–2009), commonly known as white wormwood or desert wormwood (Arabic name chih), is a greyish-strongly aromatic dwarf shrub native to the South western Europe, Northern Africa, Arabian Peninsula and Western Asia.

The economic value, the local medicinal uses, the disappearance in some areas due to pasture and over-collection, as well as the potential use to restore degraded ecosystems support the large number of studies on A. herba-alba. A recent review detailed the distribution, taxonomy, morphology, phytochemistry and biological activities of A. herba-alba and its different extracts (Mohamed et al., 2010).

Among A. herba-alba phytochemical constituents, essential oils have been extensively studied, with several chemotypes being recognized. The variability from the essential oils isolated from A. herba-alba collected at Algeria, Israel, Morocco and Spain was revised by Dob and Benabdelkader in 2006, but, since then, many other studies reinforced its high chemical polymorphism (Table 1, and references therein). Plants were collected from wild in different countries, grown under controlled experimental field conditions, collected at different harvesting times, subject to different drying periods and processes, extracted fresh or dry, by hydrodistillation or steam-distillation under different experimental conditions, and different aerial plant parts have been used (Table 1).

The aim of the present study was both to evaluate the chemical composition of the essential oils isolated from A. herba-alba collected at different locations in Algeria, and to compare these data with an updated survey on the chemical variability of this species essential oils.

2 Experimental

2.1

2.1 Plant material

The aerial parts of A. herba-alba were collected during the flowering (July, 2008) and vegetative phase of the plant (October and November, 2008) at different localities in Algeria (Benifouda; Bougaa; Boussaada and Boutaleb), characterized by diverse geographic and climate conditions (Fig. 1, Table 2). Plant material was dried in the dark, at room temperature. Certified voucher specimens have been deposited in the Herbarium of the Faculty of Nature and Life Sciences at F. A. University, Setif, Algeria.

Close

Figure 1

Algeria geographical location (a) and collection sites (b) of Artemisia herba-alba. Benifouda (Be); Bougaa (Boug); Boussaada (Bous) and Boutaleb (Bout).

Export to PPT

Table 2 Data on altitude, precipitation and temperature range at the collection sites of Algerian Artemisia herba-alba.

Average/Year	Artemisia herba-alba
	Benifouda (Be)	Bougaa (Boug)	Boussaada (Bous)	Boutaleb (Bout)
Altitude (m)	821	914	459	1321
Precipitation (mm)	500	500	17	300
Temperature (°C)	2–38	2–38	3–42	−2– 40

Data gathered from official Headquarter Maps[Carte d’État Major (CEM); CEM SoukNadjaa paper 169, CEM SaintArnaud, paper 98, CEM AinRoua, paper 69] and from the National Meteorology Office (Office National de la Météorologie).

3 Results and discussion

The aerial parts of A. herba-alba were collected at different localities in Algeria (Benifouda; Bougaa; Boussaada and Boutaleb), characterized by diverse geographic and climate conditions (Fig. 1, Table 2).

A. herba-alba populations studied afforded oils in a yield ranging from 0.2% (Boutaleb) to 0.9% (Bougaa) (v/d.w.), respectively, (Table 3). The oil yields recorded in the present study were within the ranges reported in the literature[0.1–4.9% (v/w), (Table 1)], and, as referred by Mighri et al. (2009b), where higher at the flowering phase.

A. herba-alba identified oil components are listed in Table 3 in order of their elution on the DB-1 column. Monoterpenes (78–89%) and particularly oxygen-containing monoterpenes (72–80%) dominated all oils. Sesquiterpenes ranged from 2–11% (Table 3).

A. herba-alba essential oils percentage composition was used to determine the relationship between the different samples, and allowed the definition of two clusters, Fig. 2. Cluster I was a one sample group as included only the Benifouda (Be) oil, which was dominated by camphor (33%) and chrysanthenone (12%), Table 3. Cluster II included the more correlated oil samples (S_corr > 0.88) from Bougaa (Boug), Boussaada (Bous) and Boutaleb (Bout). α-Thujone, which was < 7% in Be oil, was dominant in Cluster II sample oils (24–28%). Boug, Bous and Bout samples from Cluster II showed also large percentages of camphor (17–23%), and a wide range in chrysanthenone (4–19%) relative amount, Table 3.

Close

Figure 2

Dendrogram obtained by cluster analysis of the percentage composition of the essential oils isolated from Artemisia herba-alba samples based on correlation and using unweighted pair-group method with arithmetic average (UPGMA). Benifouda (Be); Bougaa (Boug); Boussaada (Bous) and Boutaleb (Bout).

Export to PPT

Overall, the essential oil profiles of all samples were similar (S_corr > 0.7), although with some variation in the relative amount of the three main components, camphor (17–33%), α-thujone (7–28%) and chrysanthenone (4–19%). Despite the global resemblance, three types of oils could be defined, (a) α-thujone : camphor (Bougaa and Boussaada plants oils), (b) camphor : chrysanthenone (Benifouda plant oil) and (c) α-thujone : camphor : chrysanthenone (Boutaleb plant oil), Fig. 2.

No relationship could be drawn between the chemical composition of A. herba-alba essential oils and the four regions of Algeria (Benifouda; Bougaa; Boussaada and Boutaleb) where the samples were collected, nor with the altitude of the collection sites, temperature or humidity ranges (Tables 2 and 3, Fig. 2). This was confirmed by the fact that the most similar essential oil profiles were those isolated from plants collected during the flowering phase in Bougaa and during the vegetative phase in Boussaada (Tables 2 and 3, Fig. 2).

A review of the existing literature on A. herba-alba essential oils afforded a large number of studies, particularly in the last two years (Table 1). Although the isolation procedure was similar in most cases, the plant parts, the physiological stage, the plant status (fresh or dry), and the geographical origin were quite diverse, in addition to the use of collective samples and to the possibility of existing different subspecies. Only seldom studies have used individual plants, and even in those cases no clear correlation between plant oil types and environmental conditions was established (Fleisher et al., 2002).

With high percentage variability, α-thujone (n.d. 80%) and β-thujone (n.d. 58%) were reported in studies from all countries (Table 1). Although not mentioned in Table 1, because this table includes only components with a relative amount ⩾5%, the occurrence of α-thujone and β-thujone was also reported in one study from Spain (Villar et al., 1983; in Salido et al., 2001). With exception of the work published on Jordanian A. herba-alba (Hudaib and Aburjai, 2006) (Table 1), chrysantenone (n.d. 65%), camphor (n.d. 49%) and 1,8-cineole (n.d. 28%) occurrence was always mentioned in, at least, some studies from all other countries (Table 1). In addition, with a more restricted occurrence, davanone (Spain and Tunisia) and cis-chrysanthenyl acetate (Israel, Sinai, Spain and Tunisia) attained also relatively high percentages (n.d. 51% and n.d. 69%, respectively) (Table 1). Usually one of these seven compounds or some of them, in different proportions, dominate A. herba-alba essential oils, which is in agreement with the results here reported for samples collected at different Algerian sites.

The chemical variability of essential oils from Algerian A. herba-alba emphasizes the importance of evaluating individual plant samples, as well as the worth of avoiding wild plant material collection, not only due to the innate variation, which has a negative market impact, but also to impair biodiversity depletion. In view of this, it seems most adequate to recognize which chemovariety best fits the market demands and develop sustainable culture methodologies for local A. herba-alba crop production.