Essential Oil Composition of Pimpinella barbata (DC.) Boiss. from Iran

Journal of Essential Oil Research: JEOR, Nov/Dec 2006 by Fakhari, Ali Reza, Sonboli, Ali

Abstract

The essential oil composition from the aerial parts of Pimpinella barbata (DC.) Boiss. (Apiaceae) at full-flowering stage from Iran was studied by GC and GC/MS. A total of 32 compounds have been identified, accounting for 97.0% of the total oil. Analysis of the oil showed that the oil of P. barbata was rich in a phenylpropanoid fraction, in which methyl eugenol (34.0%) and elemicin (6.9%) were the two main constituents. The main compouds of monoterpene fraction were limonene (26.6%), sabinene (6.7%) and perillaldehyde (5.2%).

Key Word Index

Pimpinella barbata, Apiaceae, essential oil composition, methyl eugenol, limonene.

Introduction

The genus Pimpinella L., belongs to the family Apiaceae, subfamily Apioideae, tribe Apieae, and it comprises about 150 species in Europe, Asia and Africa. In the flora of Iran this genus is represented by 20 species growing wild all over Iran. Pimpinella harhata (DC.) Boiss. is one of the annual native species of Pimpinella, which was found to be a wide distribution in west and south provinces of Iran (1-2).

Pimpinella anisum L. has been of great interest to the recent researches, in which the pharmacological (3-4), agricultural (5) and phytochemical (6-8) and biological (9) properties of its oil have been investigated. The effects of fruit essential oil of the P. anisum on acquisition and expression of morphine induced conditioned place preference (3), and also anticonvulsant activity of its oil in mice was studied (4). The oil composition and antimicrobial activity of some other Pimpinella species have already been reported. Estragole (91.9%) and (E)-anethole (7.2%) were found to be the main constituents of the oil of P. aromatica aerial parts from Turkey (10). The oil composition of P. serbica Benth. et Hook, fruits from Yugoslavia, has been studied and β-caryophyllene (>47.0%) reported as the major component (11). Monoterpene hydrocarbons (86.1%) constituted the major fraction of the oil of P. achilleifolia with p-cymene (52.2%) as the principal component (12). Chemical composition of the oils from the roots, fruits, leaves and stems of P. cumbrae Link, growing in the Canary Islands, has also been studied and the major constituents were (13) isokessane (17.0%) and β-dihydroagarofuran (15.0%), α-bisabolol (39.0%) and δ-3-carene (16.0%), α-bisabolol (53.0%) and δ-3-carene (11.0), and α-bisabolol (39.0%) and isokessane (10.0%), respectively. From the oil of P. junoniae, zingiberene (20.6%) and α-pinene (17.9%) were identified as the major components (14). The oil composition and antimicrobial activity of tuberous roots of P. tirupatiens Bal. et Subr. have been investigated, and α-bisabolene (9.2%) and δ-3-carene (8.9%) were determined as main components of the oil (15).

A literature survey revealed that the oil composition of P. barbata has not been investigated before; therefore to the best of our knowledge, here chemical composition of the oil of P. barbata is reported.

Experimental

Plant material: The aerial parts of Pimpinella barbata were collected from Shiraz, mountains near Maharlou Lake (Fars province, Iran), dry open hillside in June 2003 at full flowering stage. A voucher specimen has been deposited in the Medicinal Plants and Drugs Research Institute Herbarium, Shahid Beheshti University, Tehran, Iran.

Oil isolation: Air-dried aerial parts (100 g) were subjected to hydrodistillation for 3 h using a Clevenger-type apparatus. The distillate was dried over anhydrous sodium sulfate and stored at 4°C until analysis. The yield of the oil was calculated based on dry weight of plant.

GC: GC analysis of the oil was performed using a Varian CP-3800 instrument equipped with a capillary fused silica DB-1 column (25 m x 0.25 mm, film thickness 0.25 µm). Nitrogen was used as carrier gas at constant flow of 1.1 mL/min. The oven temperature was held at 60°C for 1 min, then programmed to 250°C at a rate of 4°C/min, and then held for 10 min. The injector and detector (FID) temperatures were kept at 250°C and 280°C, respectively.

GC/MS: GC/MS analysis was performed on a Thermoquest-Finnigan Trace GC/MS equipped with a fused silica DB-1 column (60 m x 0.25 mm, film thickness 0.25 µm). The oven temperature was raised from 60°-250°C at a rate of 5°C/min, then held at 250°C for 10 min; transfer line temperature, 250°C. Helium was used as carrier gas at a flow rate of 1.1 mL/min; split ratio, 1/50. The quadruple mass spectrometer was scanned over the 45-465 amu with an ionizing voltage of 70 eV and an ionization current of 150 µA.

Identification of components: The constituents of the oil were identified by calculation of their retention indices under temperature programmed conditions for n-alkanes (C^sub 6^-C^sub 24^) and the oil on a DB-1 column under the same chromatographic conditions. Identification of individual compounds was made by comparison of their mass spectra with authentic compounds or with those of the internal reference mass spectra library and confirmed by comparison of their retention indices and mass spectra either with data published in the literature. For quantification purposes relative area percentages obtained by FID were used (16-17).

Results and Discussion

The hydrodistillation of aerial parts of P. barbata gave a yellow oil in a yield of 0.5% (w/w), based on the dry weight of the plant. Thirty-two compounds were identified in the oil, representing 97.0% of the total oil. The qualitative and quantitative oil composition is presented in Table I, where the compounds are listed in order of their elution on the DB-1 column. The oil of P. barbata may be divided into monoterpene, phenylpropanoid and sesquiterpene fractions. Among the monoterpene fraction the major compounds were limonene (26.6%), sabinene (6.7%) and perillaldehyde (5.2%). Spathulenol (3.1%), bicyclogermacrene (1.3%) and germacrone (1.2%) were the principal constituents of sesquiterpene fraction. Methyl eugenol (34.0%) and elemicin (6.9%) were the two main components with a phenylpropanoid skeleton. Methyl eugenol has already been reported from the oils of Semenowia tragioldes (Boiss.) Manden (5.0%) (18), Echinophora cinerea (Boiss.) Hedge et Lamond (0.3%) (19), Ducrosia anethijalia (DC.) Boiss. (1.6%) (20) and Ferulago angulata (Schlecht.) Boiss. (4.0%) (21). Elemicin has also been reported as a main compound from the oil of Diplotaenia cachrydifolia aerial parts (22).