Analysis of the oil of Hippomarathrum microcarpum (M. B.) B. Fedtsch. from Iran

Journal of Essential Oil Research: JEOR, Jul/Aug 2003 by Sefidkon, F, Shaabani, A

Received: March 2001

Revised: May 2001

Accepted: June 2001

Abstract

The oils obtained by steam distillation of the leaves and flowers of Hippomarathrum microcarpum (M. B.) B. Fedsch. growing wild in Iran were investigated by a combination of GC and GC/MS. Thirty-one compounds in the leaf oil, and 28 compounds in the flower oil have been identified. The main constituents of the leaf oil were [beta]-caryophyllene (26.4%), [gamma]-muurolene (19.0%) and linalool (6.1%); the major components of the flower oil were [beta]-caryophyllene (18.5%), [gamma]-muurolene (19.2%), thymol (6.9%), camphene (6.4%) and linalool (5.9%).

Key Word Index

Hippomarathrum microcarpum, Umbelliferae, essential oil composition, [beta]-caryophyllene, [gamma]-muurolene.

Introduction

The genus of Hippomarathrum, with the common Persian name of horse fennel, possess only one species found in Iran, namely H. microcarpum, which is found wild in many mountainous regions of Iran (1).

The oil of H. microcarpum has not been the subject of previous study, but there are some references about coumarins and furocoumarins in its root and fruits (2-4). The purpose of this investigation was to analyze the chemical composition of the leaf and flower oils of H. microcarpum from Iran.

Experimental

Plant material: The aerial parts of H. microcarpum were collected in May and August 1998, respectively, from Velenjak at the north of Tehran. The herbarium specimens have been deposited in the Herbarium of the Research Institute of Forests and Rangelands (TARI).

Isolation of the oil: The oils were prepared by steam distillation of leaves and flowers separately. The oils, which were pale yellow in color, were dried over anhydrous calcium chloride and stored in sealed vials at low temperature prior to analysis.

Qualitative and quantitative analysis: The oils were investigated by capillary GC and GC/MS. GC analysis were performed using Shimadzu GC-9A equipped with a DB-1 column (60 m x 0.25 mm, film thickness 0.25 [mu]m). Oven temperature was held at 50[degrees]C for 5 min and then programmed to 250[degrees]C at a rate of 4[degrees]C/min; injector and detector (FID) temperature were 260[degrees]C, carrier gas: helium with a linear velocity of 32 cm/s. GC/MS analysis were carried out on a Varian 3400 GC/MS system equipped with a DB-1 fused silica column (60 m x 0.25 mm, film thickness 0.25 [mu]m); oven temperature, 50[degrees]-250[degrees]C at a rate of 4[degrees]C/min, transfer line temperature 260[degrees]C, carrier gas, helium with a linear velocity of 31.5 cm/s; split ratio 1/60; ionization energy 70 eV; scan time 1 s; mass range 40-300.

Peak areas and retention times were measured by electronic integration. The relative amounts of individual components were based on the peak areas obtained, without FID response factor correction. Temperature programmed retention indices of the compounds were determined relative to the retention times of a series of n-alkanes. The constituents were identified by comparison of their mass spectra with those in the computer library or with authentic compounds and confirmed by comparison of their retention indices either with those of authentic compounds or with data in literature (5,6).

Results and Discussion

The oils isolated by steam distillation from the leaves and flowers of H. microcarpum were obtained in yields of 0.18% and 0.24% (w/w), respectively, based on dry weights. Thirty-one components were identified in the leaf oil and 28 components were identified in the flower oil of H. microcarpum.

The components identified in both oils are listed in order of their elution on the DB-1 column. From Table I, it is evident that the compositions of the leaf and flower oils do not differ sharply. The main components of leaf and flower oils were [beta]-caryophyllene (26.4% and 18.5%), [gamma]-muurolene (19.0% and 19.2%), linalool (6.1% and 5.9%), thymol (3.6% and 6.9%), camphene (4.3% and 6.4%), and bornyl acetate (2.8% and 5.4%). Some of components in the leaf oil were not found in the flower oil like limonene, (Z)- and (E)-[beta]-ocimene and [beta]-sesquiphellandrene. The sesquiterpenes, [gamma]-cadinene (2.6%), spathulenol (0.2%) and [alpha]-cubebene (0.2%) were found only in the flower oil.

Comparing these results with that of H. boissieri from Turkey (7) showed, the main component of the oils from both species is [beta]-caryophyllene (26.4% for leaf oil and 18.5% for flower oil of H. microcarpum and 25.6% for aerial parts oil of H. boissieri).

Some of the other main components of H. microcarpum oil, such as [gamma]-muurolene, camphene and thymol, were also found in the oil of H. boissieri in trace amounts (less than 0.5%). Linalool was not found in H. boissieri oil. The other main components of H. boissieri oil, such as caryophyllene oxide (9.4%) and [alpha]-pinene (8.8%), were found in H. microcarpum oils in lower amounts.

Acknowledgments

The authors would like to acknowledge the financial support given by the Shahid Beheshti University for this work. We are grateful to Dr. Mirza and Ms. Barazandeh for injection of the oils to GC/MS and GC.