Analysis of Moroccan Atlas Cedarwood Oil (Cedrus atlantica Manetti)
The yield and the chemical composition of Atlas cedarwood oil produced by two distillation modes and seven sample origins were determined. Steam distillation and hydrodistillation gave approximately the same yield (2.5-2.6 mL/100g). The samples from Adrej, Tounfite, Tamjilt and Ajdir gave the highest oil yields. The major constituents in the essential oil were α-himachalene (7.4-16.4%), γ-himachalene (5.1-8.6%), β-himachalene (23.4-40.4%) and (E)-α-atlantone (5.2-29.5%).
Key Word Index
Cedrus atlantica, Cupressaceae, essential oil composition, α-himachalene, β-himachalene, (E)-α-atlantone, geographic variation.
Atlas cedar (Cedrus ntlantica Manetti) is the principal species in Moroccan forests used for production of timber. It is essentially encountered at a high altitude with a surface distribution area of 132,000 ha between Rif, middle and high Atlas. This species can reach 40 m in height and 1 in in diameter. Moroccan cedar plantations arc responsible for the production of 100,000 m^sup 3^ timber per year (1). The machining waste, often under-valued, is estimated to be 30% (2); thus sawdust production is estimated to be 18,000 tonnes. This raw material would be important for essential oil production to be used for its medicinal properties and perfumery. Indeed, essential oils are a part of several products such as drugs, perfumes etc. (3,4). The essential oil of cedarwood is rich in himachalenes (70%) (5). Essential oils of cedar are also used for hemi-synthesis of products, such as the arylhimachalones, needed in perfumery (7).
In this work, the yield and the chemical quality of the Atlas cedarwood oils obtained from trees harvested from the middle Atlas forest were studied. The oils were produced both by hydrodistillation and steam distillation. The results of this study could contribute to a better utilization of this raw material scrap. Indeed, oil isolation from Atlas cedarwood would allow a more profitable cedar planting and would offer socio-economic benefits such as currency supply and job creation.
The studied sawdust samples were provided from the cedar plantation of the central and eastern middle Atlas (Figure 1). Seven provenances were studied: the central middle Atlas (central Moroccan) is represented by Ajdir and Tounfite localities, characterized by forests grown on limestone1 in a semi-arid climate, and Sidi Mgnild and Wiwnne localities characterized by forests grown on basaltic soils in a sub-humid climate. The eastern middle Atlas is represented by Adrej and Tamjilt localities, characterized by forests grown on limestone and an arid climate.
The isolation of oils was achieved by hydrodistillation and steam distillation. The hydrodistillation was carried out using a Clevenger-type distillation system. The distillation of each sample lasted approximately 8 h. For each distillation, a mixture of 150-200 g of sawdust and 750 mL of water was used. For the steam distillation, 500 g of sawdust was used. The flash containing the sawdust was heated to avoid steam condensation.
Four isolations were carried out for each sawdust sample. Each oil was subjected to the Chromatographie analyses. Previously, humidity of a sample representative of the sawdust was determined by drying it at 70°C to constant weight. The humidity rate of studied samples was about 19-25%. The average oil contents were calculated from the dry matter and expressed in mL/lOOg. Variance analyses were achieved by Systat 7.2 statistical software.
Gas Chromatographie (GC) analyses were performed with a Hewlett-Packard (HP 6890), equipped with a capillary column HP-5 (30m × 0,25mm, 0.25 µm film thickness) and a detector FID at 250°C. Provided by H^sub 2^/Air gas mixture and split-splitless injector heated at 250°C. The injection mode is split. The vector gas used is N^sub 2^ with 1.5 mL/min. The column temperature was programmed from 60°-220°C at 3°C/min. The apparatus was guided by a computer system type “HP ChemStation,” which manages the apparatus functioning and allows monitoring of Chromatographie analyses. The injected volume was about 1 µL.
The identification of constituents was achieved on the basis of retention indices and gas chromatography/mass spectrometry (GC/MS). The GC/MS analyses were performed on a Hewlett-Packard (HP 6890) equipped with an automatic injector (HP 7683) and coupled with a mass spectrometer (HP 5973). Fragmentation was by electronic impact under 70 eV field. The column used was a capillary column HP-5MS (5% phenyl methyl siloxane: 30 m × 0.25 mm, 0.25 µm film thickness). The vector gas was H^sub 2^ with 1.5 mL/min. The column temperature was programmed from 60°-220°C at 3°C/min. The oil components were identified by comparing the retention indices of authentic materials with those of substances present in the mixture and by further confirming their identities MS (library of NIST 98 spectra).
Results and Discussion
Yields in essential oils: The results showed that the two types of isolation provided approximately similar oil yield values (2.5 against 2.6 mL/lOOg) (Table I). They were confirmed by statistical analyses indicating that there is no significant difference between the two types of oil isolation procedures on yield.
The sawdust samples coming from Adrej and Tamjilt, Tounflte and Ajdir localities gave the best yields. The Adrej samples were the richest in oils with a yield of 6.1 mL/lOOg, followed by those of Tounfite with 5.6 mL/lOOg, Tamjilt with 5.1 mL/lOOg and those of Ajdir with 4 mL/lOOg (Table II). The variance analysis indicated a very high significant difference (Fobs = 137). These results allow the classification of this provenance into three different groups: Adrej, Tounfite, Tamjilt and Ajdir was the first group with an average content of 5.2 m L/ 10Og. The second group was composed by Sidi Mguild and Wiwane provenance with an average yield of 2.5 mL/lOOg. The last group was constituted by Ras El Ma with 1.7 mL/lOOg.
The differences recorded between these groups could be assigned to the bioclimatic conditions of the different localities studied. The highest yields were obtained in semi-arid climate with sawdust of cedar growing on dolomitic and calcareous soils (Aderj, Tounfite, Tamjilt and Ajdir forest localities). While the low yields were observed in the sub-humid climate (fresh summer and cold winter: Sidi Mguild, Ras El ma and Wiwane forest localities) with sawdust of cedar growing on volcanic soils (basaltics) (8,9). A previous study on cedar productivity in the central middle Atlas stations, revealed that cedar plantations grown on basalt soils were the most productive, whereas the cedar plantations on dolomitic soils provided a finer wood with appreciable quality (10). The later is characterized by very thin and regular annual increment, which indicates that the trees growing under adverse conditions induce the production of terpenes and the resins. According to these results, the production potentialities of the Moroccan cedar plantations could roughly amount to 700 tonnes/year of cedarwood oil.
Chemical composition of the Atlas cedarwood essential oils: The results of the Chromatographie analyses of the various oils samples are shown in the Tables III and IV, and are illustrated in Figure 2. These analyses allowed us to identify approximately 40 components. The studied various samples present a relatively similar chemical composition with α-, β-andy-himachalene, deodarone and (E)-β-atlantone as dominant components. These products amount to approximately 70% of these oils (Tables III and IV). Others components such as δ-cacUnene, I- epi-cubenol, himachalol, (E)-γ-atlantone and (Z)-α-atlantone were present only at levels of 1-4%, representing 10-20% of the oils. The components with percentages less than 1% represent almost 10% of the oil. These values change according to the samples origin and the type of isolation (Tables III and IV). These results confirm those of other authors (6,11,12).
The results showed that the contents of the most volatile products (fore-running of distillation) of oil samples obtained by steam distillation were higher than those obtained by hydrodistillation. Indeed, the average contents of α-, γ- and β-himachalenes, were 11.6%, 7.5% and 33.8%), respectively for the oils obtained by steam distillation compared with 5.0%, 4.2% and 14.1%, respectively for those obtained by hydrodistillation (Table III). This corresponds to a reduction equal to 2/3 for α-himachalene and about 1/2 for γ- and β-himachalenes. On the contrary, the content of the less volatile components were more important in the oils obtained by hydrodistillation than those obtained by steam distillation (Figure 2). Himachalol, deodarone and (E)-α-atlantone each present a content approximately double for the oils obtained by hydrodistillation (5.8%, 8.5% and 22.0%, respectively) than for the oils obtained by steam distillation (2.4%, 4.9% and 12.1%, respectively).
These differences could be explained by the fact that during hydrodistillation, the direct contact of sawdust with hot water may be in favor of bursting glands thereby allowing the isolation of the more heavy products. It is also probable that hydrodistillation can cause a partial degradation of some compounds by hemi-synthesis. Thus, it was mentioned that hydrodistillation can lead to the management of some terpenes and their decomposition ( 13,14). This decomposition can be favored by an acidic pH. Indeed during hydrodistillation, the phenols and acids can be released from sawdust and they can accelerate the decomposition of some components according to the temperature and their concentration (4,15,16). However, the most currently required products by pharmaceutical industries and perfumery are the himachalenes and their derivatives (7,5). The highest contents of these products were obtained by steam distillation.
The chemical composition of the oils obtained by steam distillation and from the sawdust samples of the different localities presents some differences with a slight superiority of Adrej and of Wiwane samples (Table IV). The α-, γ- and β-himachalene, the deodarone and (E)-α-atlantone always remained the major compounds of these oils. The β-himachalene was the principal component with a variable content of 23.4-40.4%. The oils of Wiwane and Adrej samples were richer in this component with a content of about 40%. The lowest β-himachalene content was observed in Tamjilt oil with 23.4%. The content of a-himachalene varied between 7.4% for oils isolated from sawdust of Tamjilt samples to 16.4% for those of Wiwane samples. The percentage of γ-liimachalene varied from 5.1-9.7% for Tamjilt and Wiwane samples, respectively (Table IV). In Sidi Mguild samples, the content of (E)-α-atlantone was 5.2% against 29.5% noted in the Tamjilt samples. For the other localities, the (E)-α-atlantone content reached 12% [8.9% for Adrej, 13.4% for Tounfite and 9.1% for Ajdir (Table IV)], The highest content of deodarone was recorded in oil samples of Tamjilt with 7.7% against 4.4%, 3.9% and 1.2% respectively for Tounfite, Ajdir and Wiwane samples. The content of δ-cadinene, 1-epi-cubenol, himachalol, (E)-γ-atlantone and (Z)-α-atlantone varied from 1-5.9% (Table IV). The remainder of the components showed a slight difference in percentages between samples of less than 1% (Table IV).
The climatic and edaphic conditions seem to have an effect on the chemical composition of oils of Atlas cedar wood. This influence was marked for the major components of the oils. The age of trees can also influence these results. However, this factor was not approached in this work. The studied samples came primarily from the trees logged for sawing. The production of oils from the Atlas cedarwood cannot be considered unless it is associated with the prodiiction of sawdust.
It can be concluded that the yield and composition of oils of the Atlas cedarwood sawdust of Moroccan middle Atlas were determined in different sources of samples and with two types of isolation procedures. The steam distillation and hydrodistillation showed approximately the same oil yields, but a relatively different chemical composition. Compared to steam distillation, the hydrodistillation contained lower contents of the most volatile components and higher contents of the less volatile components. The oil yield and composition also varied according to the origin of samples. The Tounfite, Adrej, Tamjilt and Ajdir samples showed the highest yields. The chemical quality of these oils was characterized by α-, γ- and β-himachalene, deodarone and (E)-α-atlantone as major products, and these compounds varied with the origin of samples. The production of compounds with added value by hemi-synthesis, such as himachalene epoxides, would constitute a better added value of this raw material whose production potentialities were estimated at approximately 700 tonnes/ year.
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Mohamed Aberchane* and Mohamed Fechtal
Centre National de la Recherche Forestière, Rabat, BP. 763 Rabat-Agdal, 10050, Morocco
Département de Chimie, Faculté des Sciences Ihn Tofail, RP. 133. Kénitra, Morocco
* Address for correspondence
10410 -2905/04/00060 -0542S6.00/00-© 2004 Allured Publishing Corp.
Received: January 2002
Revised: July 2002
Accepted: August 2002
Copyright Allured Publishing Corporation Nov/Dec 2004
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