Content and composition of essential oils in some Asteraceae species

The content and composition of the essential oils of five Asteraceae species from Estonia were studied. The oil yields ranged from traces up to 0.2%. By using GC-FID and GC-MS methods a total of 115 compounds were identified and significant qualitative and quantitative differences were observed among the studied species. The main constituents of the essential oils of the studied Asteraceae species were as follows: Chamomilla recutita: bisabolol oxide A (39.4%), bisabolone oxide A (13.9%), (Z)-en-yne-dicycloether (11.5%), bisabolol oxide B (9.9%), α-bisabolol (5.6%), and chamazulene (4.7%); Chamomilla suaveolens: (Z)-en-yne-dicycloether (37.2%), geranyl isovalerate (22.9%), (E)-β-farnesene (15.6%); Anthemis tinctoria: α-eudesmol (10.2%), γ-cadinol (8.7%), γ-cadinene (4.0%); Matricaria perforata: (Z,Z)-matricaria ester (77.9%), (E)-β-farnesene (3.5%), matricaria ester isomer (3.5%), and matricaria lactone (3.0%); and Leucanthemum vulgare: (E)-β-farnesene (7.3%), hexadecahydrocyclobuta[1,2:3,4]dicyclooctene (5.3%), decanoic acid (4.9%), and γ-eudesmol (4.5%). The number of compounds found in all plant oils studied was 14.


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The Asteraceae family contains several species known as popular medicinal plants.The concept that plants can be classified also on the basis of their chemical constituents is not new [1,2].According to an earlier study [3], the most popular medicinal plant in Estonia during the 20th century was Chamomilla recutita (L.) Rauschert (= Matricaria recutita L.), which was also very widely used in the Soviet Union, Russia, Germany, etc.In several publications (an overview in [3]) it is observed that the chemical composition of the essential oil of Chamomilla recutita is rather similar to that of Chamomilla suaveolens (Pursh) Rydb.(= Matricaria suaveolens (Pursh) Buch.; M. discoidea DC.; M. matricarioides (Less.)Porter).The chamomile inflorescence is anti-inflammatory and spasmolytic [4].
These three species are not yet known as medicinal plants of allopatic medicine.The antibacterial and bactericidal activity of extracts and their fractions of aerial parts of Anthemis tinctoria against Staphylococcus aureus, Pseudomonas aeruginosa, and Enterococcus faecalis was determined [6].Mogosan et al. [7] mentioned that the tincture of A. tinctoria promotes potassium retention, the saponins of the same species increase urinary excretion of uric acid.According to the Patent No. RU 2311194, the extract of Leucanthemum vulgare is a constituent of a homeopathic agent possessing an antiviral effect [8].
The current paper presents the content and the results of GC-FID and GC-MS analyses of the essential oils of inflorescences of Chamomilla recutita, Chamomilla suaveolens, Anthemis tinctoria, Matricaria perforata, and Leucanthemum vulgare growing in Estonia.

Plant material
The plant material -samples of herbs of wild-growing Anthemis tinctoria, Matricaria perforata, Leucanthemum vulgare, and Chamomilla suaveolens -was collected in July 2007 from North Estonia (Harjumaa, Virla).The sample of Chamomilla recutita was from a cultivated plant and it was collected in June 2007 in the experimental garden of the University of Tartu.All collected fresh samples were dried at room temperature in a well-ventilated room.The dried drug samples were preserved in tightly closed bumper bags at room temperature in the absence of light.Voucher specimens and drug samples are deposited at the Department of Pharmacy, University of Tartu, Estonia.

Isolation of essential oil
The essential oils were isolated from dried samples of Asteraceae species by the distillation method described in the European Pharmacopoeia [39] for Matricariae flos by using the Clevenger-type apparatus.A 1000 mL round-bottomed flask, 30 g of plant material, and 300 mL of water as the distillation liquid were used.Cyclohexane (1 mL in a graduated tube) was added to take up the essential oil.The distillation time was 4 h at a rate of 3-4 mL/min.The oils were stored prior to analysis in ampoules and were analysed within a week.

Gas chromatography with FID
The essential oils were analysed using a Chrom-5 chromatograph with FID on two fused silica capillary columns with two stationary phases: poly(5% diphenyl-95% polydimethyl siloxane) (SPB TM -5, 30 m × 0.25 mm, Supelco, Switzerland) and polar polyethylene glycol (SW-10, 30 m × 0.25 mm, Supelco, Switzerland).Film thickness of both stationary phases was 0.25 µm.Helium with the split ratio 1 : 150 and the flow rate 30-35 cm/s was applied as the carrier gas.The temperature program was from 50 to 250 °C at 2 °C/min, the injector temperature was 250 °C.A Spectra-Physics SP4100 integrator was used for data processing.
The identification of the oil components was accomplished by comparing their retention indices (RI) on two columns with the RI values of reference standards, our RI data bank, and with literature data [40][41][42][43].
The percentage composition of the oils was calculated in peak areas using the normalization method without correction factors.The relative standard deviation of percentages of oil components of three repeated GC analyses of a single oil sample did not exceed 5%.

Gas chromatography-mass spectrometry
GC/MS analysis was carried out using GCMS-QP2010 (Shimadzu, Japan) on a fused silica capillary column (30 m × 0.32 mm) with a bonded stationary phase: poly(5% diphenyl-95% dimethyl siloxane) (ZB-5, Zebron).The film thickness of the stationary phase was 0.25 µm.The carrier gas was helium with the split ratio of 1 : 8 and flow rate 44.4 cm/s.The temperature program was 1 min at 60 °C and then from 60 to 300 °C at 8 °C/min.The injector temperature was 280 °C.The MS source temperature was 200 °C.The MS detector was operated in the EI mode 70 eV at a scan rate 2 scans/s with an acquisition mass range of 40-500 u.

Content of essential oils
The content of essential oils in the investigated plants of Asteraceae species ranged from traces up to 0.2% based on dry weight (Table 1).The highest oil content was found in Matricaria perforate (0.2%) and the lowest in Anthemis tinctoria (only in traces).As it was shown in [38], the content of essential oil in the individual floral parts of A. tinctoria from Slovakia ranges from 0.02% to 2.78%.The highest content of essential oil was found in the tongue-shaped flowers in the second development stage.
A very low yield of essential oil (0.03%) was found also in the sample of Leucanthemum vulgare of Estonian origin.The essential oil of L. vulgare from Georgia made up 0.4-0.5% of the air-dried mass [36].
The extremely low concentrations of essential oil in A. tinctoria and L. vulgare can probably be explained by the origin of the investigated samples.Our earlier experience shows that there may exist a significant difference between the minimum and maximum yield of essential oil in other plants: 10-fold difference in Chamomilla recutita [23], 11-fold in Achillea millefolium [44] and Salvia officinalis [45], 16-fold in Levisticum officinale [46], 14-fold in Thymus serpyllum [47], 5-fold in Pimpinella anisum [48], and 6-fold in Valeriana officinalis [49] collected or obtained as commercial samples from different retail pharmacies of various countries.
The Chamomilla species -C.recutita and C. suaveolens -contained 0.15% and 0.12% essential oil, respectively.According to the standards of the 10th edition of the U.S.S.R Pharmacopoeia [50], the inflorescences of C. recutita and C. suaveolens should contain at least 0.3% and 0.2% essential oil.Consequently, the oil yield in the investigated Asteraceae species was rather low although the distillation method corresponded to the monograph of Matricariae flos (inflorescences of C. recutita) in the European Pharmacopoeia [39] and the distillation time (4 h) was quite long.

Composition of essential oils
Essential oil components of five Asteraceae species and their percentages and mode of identification are reported in Table 1.A total of 115 compounds were identified in the studied samples, which accounted for 49.1-98.5% of the total amount of oil.The largest number of compounds were identified in the oil of Matricaria perforata (84).In other oils 52-62 compounds were identified.From the essential oil of the flower heads of M. perforata growing in Germany about 50 compounds were found [34].The amount of polyacetylenes in the oil of M. perforata from Estonia (88.6%) was practically equal to their concentration found in Germany (88.8%) [34].
In the oil of Leucanthemum vulgare we succeeded in identifying only 49.1% of the total oil.The mass spectra of 23 incompletely identified peaks are presented in Table 2.The oil of L. vulgare contained much more aliphatic acids and esters than the oils of the other investigated Asteraceae species  but had a very low concentration of polyacetylenes (Table 1).
Chamazulene is the typical constituent of the essential oil of C. recutita.It has been found in the range from 0.7% to 15.3% in samples of C. recutita [19,23] and from 0% to 42% in Achillea millefolium growing wild and/or cultivated in different countries [44], but was not found in the oil of C. suaveolens [33].The presence of chamazulene in the essential oil of C. suaveolens may depend on its chemotypes or growing places.

CONCLUSION
In this study the content and composition of inflorescences of five Asteraceae species were investigated.The oil yield in the investigated Asteraceae species was rather low.The composition of the essential oils of these five species was compared.Only 14 compounds were found in all analysed oils.The composition of the oils of Chamomilla recutita, C. suaveolens, and Matricaria perforata was relatively similar; however, the oil of Leucanthemum vulgare was quite different from the other oils studied.

Table 2 .
Mass spectral data of unidentified compounds