Essential Oil of Tanacetum polycephalum Schultz-Bip. subsp. argyrophyllum (K. Koch.) Podlech from Iran, The

Abstract

Essential oils isolated by hydrodistillation from the aerial parts of Tanacetum polycephalum Schultz-Bip. subsp. argyrophyllum (K. Koch.) Podlech before flowering and at full flowering stage, were analyzed by a combination of capillary GC and GC/MS. Twenty-five components were identified that approximately constitute 92.8% and 97.9% of the oils, before flowering and full flowering stage, respectively. The main constituents of the oils were camphor (36.1% and 18.5%), pinocarvone (20.1% and 31.4%), α-pinene (8.6% and 9.5%), p-cymene (9.2% and 0.5%) and bornyl acetate (8.8% and 5.9%) before flowering and full flowering stage, respectively. 1,8-cineole (18.5%) was found only in the oil of full flowering. There were some other differences between the minor components of the oils in two harvesting time.

Key Word Index

Tanacetum polycephalum, Asteraceae, essential oil composition, camphor, pinocarvone.

Introduction

The genus of Tanacetum belonging to Asteraceae family represents 26 species in Iran (1), 12 of which are endemic.

Due to our searches in literature the oil of Tanacetum polycephalum Schultz-Bip. subsp. argyrophyllum (K. Koch.) Podlech has not been the subject of previous study, but there are some studies on the chemical composition of oils from other Tanacetumpolycephalum subspecies or other Tanacetum species (2-8).

In this paper, we would like to report on the oil yield and chemical composition of T. polycephalum ssp. argyrophyllum in two stages of growth, a plant which can be found growing wild in mountainous regions of western Iran.

Experimental

Plant Material: The aerial parts of Tanacetumpolycephalum subsp. argyrophyllum were collected from west Azarbaidjan province, Bluze conservation region at an altitude of 2200-2240 m before flowering and at the full flowering stage on June and July 2003, respectively. The voucher specimens (before flowering: 6783, full flowering: 6784) have been deposited in the Herbarium of the Research Institute of Forests and Rangelands (TARI).

Isolation procedure: Air-dried aerial parts of the plants (5Og, in triplicate) for both harvesting, individually, were subjected to hydrodistillation for 2.5 h using a Clevenger-type apparatus. The oils were obtained in 0.22% and 0.47% (w/w) yield, before flowering and at the full flowering stage, respectively. The ods were dried over anhydrous sodium sulfate and stored in sealed vials at low temperature before analysis.

Gas chromatography: GC analyses were performed using a Shimadzu GC-9A gas Chromatograph equipped widi a DB-5 fused sdica column (30 m x 0.25 mm., film tìiickness 0.25 µm). Oven temperature was held at 40°C for 5 min and then programmed to 250°C at a rate of 4°C/min. Injector and detector (FID) temperature were 260°C; He was used as carrier gas with a linear velocity of 32 cm/s.

The percentages of compounds were calculated by the area normalization method, without considering response factors.

Gas Chromatography-Mass Spectrometry: GC/MS analyses were carried out on a Varian 3400 GC/MS system equipped with a DB-5 fused silica column (30 m x 0.25 mm., film thickness 0.25 µm); Oven temperature was 40°-240°C at a rate of 4°C, transfer fine temperature 260°C, injector temperature 250°C, carrier gas He with a linear velocity of 31.5 cm/s, split ratio 1/60 , flow rate 1.1 mL/min, Ionization energy 70 eV; scan time 1 s ; mass Range 40-350 amu.

Identification of Components: The components of die oil were identified by comparison of their mass spectra with those of a computer library or with authentic compounds and confirmed by comparison of their retention indices either with those of authentic compounds or with data published in the literature (9). The retention indices were calculated for all volatile constituents using a homologous series of n-alkanes on the non- polar column.

Results and Discussion

Sixteen compounds were identified in the oil of T. polycephalum subsp. argyrophyllum, before flowering, representing 92.8% of the oil. The major components of the od were camphor (36.1% ), pinocarvone (20.1% ), p-cymene (9.2%), bornyl acetate (8.8%) and α-pinene (8.6%).

Nineteen components were identified in the oil of T.polycephalum subsp. argyrophyllum, at the full flowering stage, representing 97.9% of die od. The main constituents of the oil were pinocarvone (31.4%), camphor (18.5%), 1,8-cineole (18.5%), α-pinene .(9.5%) and bornyl acetate (5.5%).

Chemical composition of the T. polycephalum subsp. argyrophyllum oils can be seen in Table I. The components are fisted in order of their elution from DB-5 column. Comparison of the oil composition showed that the amounts of the main and some minor components were different in the oils before flowering (BF) and at the full flowering (FF) stages. For example 1,8-cineole (18.5%) was found only in the FF oil.

The percentage of camphorin BF (36. 1%) od was about twice that of FF (18.5%) oil, whereas the percentage of pinocarvone in the od of BF (20.1%) was lower than FF(31.4%).p-Cymene was found in the oil of BF (9.2%) as major compound but it was present in FF stage at 0.5%. Some minor components like sabinene, β-pinene, limonene, γ-terpinene, cis-p-mendi-2-enl-ol, borneol, germacrene-D and bicyclogermacrene were found just in the od of FF stage whde some other components like camphene, α-terpinene, artemisia ketone, myrcenol and sabinyl acetate were found only in BF stage.