Comparative chemical composition of the essential oils of Iranian Achillea oxyodonta from different ecological regions

Article history: Received on: 29/04/2015 Revised on: 08/05/2015 Accepted on: 22/05/2015 Available online: 27/05/2015 Hydro-distilled volatile oils from the aerial parts of Achillea oxyodonta (collected from two different locations), which is endemic to Iran, was analysed by GC and GC–MS. In the oil of A. oxyodonta from Shemshak sample, 54 compounds representing 95.68% of the total oil were characterized with camphor 13.18%; spathulenol 11.19%; 1,8-cineole 10.51%; salvial-4(14)-en-1-one 4.82%; eudesm-4-en-6-one 3.17%; caryophyllene oxide 3.07%; filifolone 3.03% as the major components. In the oil obtained from A. oxyodonta sample collected in Soleghan, 49 compounds representing 97.98% of the oil were characterized. spathulenol 13.13%; camphor 12.83%; 1,8-cineole 11.15%; cis-β-Farnesene 8.21%; α-Cadinol 4.83%; salvial-4(14)-en-1-one 4.19%; bornyl acetate 4.16%; isospathulenol 3.64%; germacrene D 3.45%; endo-1,5-Epoxysalvial-4(14)-ene 3.09% was found as the main components. The results showed that there are qualitative similarities between the oils although the amounts of some corresponding compounds are different indicating that environmental factors strongly influence its chemical composition.


INTRODUCTION
The genus Achillea L. (Asteraceae), with about 115 species, is widely distributed in Europe, Asia and northern Africa and is naturalised in other parts of the world.The plants are perennial herbs and sub-shrubs with alternate, ordinary dentate to pinnatisect leaves and flower heads in dense corymbs (Oberprieler et al., 2007).Nineteen species of this genus have been recognized in Iran; seven of these species are endemic (Rechinger, 1963;Mozaffarian, 2009).
The plant Achillea oxyodonta investigated in this report is an endemic species of Iran which finds habitat in centre and west of Iran (Podlech, 1986).The study concerning the composition of A. oxyodonta oil is very limited.Until now, we have found only one published report on phytochemical composition of this species collected from Latian region in East of Tehran (Esmaeili et al., 2006).
In the present work, we investigated the essential oil content and chemical composition of Iranian A. oxyodonta collected from two different localities in North and Northwest of Tehran province.

Plant materials
The aerial parts of A. oxyodonta (sample 1,2) were collected during the flowering period in 14 June 2013 from Shemshak, the North of Tehran, at 2240 m altitude (sample 1) and 13 June 2013 from Soleghan, the Northwest of Tehran, at 1450 m altitude (sample 2) respectively.Voucher specimens have been deposited at the Herbarium Ministerii Iranici Agriculture (Voucher no.63062-IRAN (sample 1) and 63061-IRAN (sample 2)).

Isolation of the essential oils
Aerial parts (150 g each) of the air dried plant samples 1, 2 from two various locations in Tehran province were separately subjected to hydro distillation for 4 hours using a Clevenger type apparatus according to the method recommended in the British Pharmacopoeia.The essential oil content determined was based on dry matter.Oils were obtained in 0.89% (sample 1) and 0.78% (sample 2) (w/w) yields.The oils were dissolved in n-hexane (Merck), dried over anhydrous sodium sulphate and stored at +4 ˚C until tested and analysed.

Essential oil analysis
Gas chromatography-flame ionization detector (GC-FID) analyses of the oil were conducted using a Thermoquest-Finnigan instrument (Thermo Fisher Scientific, USA) equipped with a DB-5 fused silica column (60m × 0.25mm i.d., film thickness 0.25μm).Nitrogen was used as the carrier gas at the constant flow of 1.1ml/min.The split ratio was 1/50.The oven temperature was raised from 60ºC to 250ºC at a rate of 5ºC/min.The injector and detector (FID) temperatures were kept at 250ºC and 280ºC, respectively.GC-MS analysis was carried out on a Thermoquest-Finnigan Trace GC-MS instrument equipped (Thermo Fisher Scientific, USA) with the same column and temperature programming as mentioned for GC.Transfer line temperature was 250ºC.Helium was used as the carrier gas at a flow rate of 1.1ml/min with a split ratio equal to 1/50.Mass spectra were taken at 70 eV.

Identification of the oil components
The constituents of the essential oils were identified by calculation of their retention indices under temperature-programmed conditions for n-alkanes (C6-C24) and the oil on a DB-5 column under the same conditions.Identification of individual compounds was made by comparison of their mass spectra with those of the internal reference mass spectra library (Wiley7n.1)or with authentic compounds and confirmed by comparison of their retention indices with authentic compounds or with those of reported in the literature (Adams, 1995).Semiquantitative data was obtained from FID area percentages without the use of correction factors.

RESULTS AND DISCUSSION
The hydrodistillation of the aerial parts of A. oxyodonta samples collected from two different locations in Tehran province gave greenish yellow oils with a yield of 0.89% (sample 1) and 0.78% (sample 2), on dry weight basis (w/w).The general chemical profiles of the tested oils, the percentage content of the individual compounds except the components with trace amounts (<0.20%) and retention indices are summarized in Table 1.Fiftyfour compounds were identified in A. oxyodonta oil from Shemshak sample representing 95.68% of the oil; 49 compounds were identified in the oil from Soleghan sample representing 97.98% of the oil (Table 1).Main components of the first sample from Shemshak were camphor 13.18%; spathulenol 11.19%; 1,8cineole 10.51%; salvial-4( 14)-en-1-one 4.82%; eudesm-4-en-6-one 3.17%; caryophyllene oxide 3.07%; filifolone 3.03% and second sample Soleghan were spathulenol 13.13%; camphor 12.83%; 1,8cineole 11.15%; cis-β-Farnesene 8.21%; α-Cadinol 4.83%; salvial-4(14)-en-1-one 4.19%; bornyl acetate 4.16%; isospathulenol 3.64%; germacrene D 3.45%; endo-1,5-Epoxysalvial-4(14)-ene 3.09%.Other components were present in amounts less than 3% (Table 1).Both A. oxyodonta oils were rich in camphor, spathulenol and 1,8-cineole however, other components with rather high amounts showed variation.For example, Sample from Soleghan had bornyl acetate, cis-β-Farnesene and α-Cadinol in rather high amounts unlike Shemshak sample.From Table, it is evident that there are many qualitative similarities between the oils although the amounts of some corresponding compounds are different; it may be related to the different geographical origins of the samples.In a previous investigation on A. oxyodonta, twentyeight components were identified in the oil of plant, making up 96.4% of total composition (Esmaeili et al., 2006).The main constituents were 1,8-cineole (38.5%), artemisia ketone (23.0%), α-pinene (4.4%), sabinene (4.1%), chrysantenone (3.7%) and piperitone (3.0%).In regard to the previously reported chemical composition of A. oxyodonta essential oil, it is interesting to point out that there are important qualitative and quantitative differences between the present work and that study suggesting that the environmental factors strongly influence its chemical composition.For instance, spathulenol was found to be the major constituent of A. oxyodonta essential oil in our research (Table 1); it was not detected in previous report.On the contrary, artemisia ketone, which was not present in our samples, was assayed to be the main component in the previous report.

CONCLUSIONS
In general, these findings confirmed that essential oil composition of plant can be different in quality and quantities in different geographical and environmental conditions and period of growth of plant.Thus to obtained uniform chemical contents, we recommend that the plants should be grown in cultural conditions as the next step.