Composition of essential oils from five endemic Sideritis species**

Journal of Essential Oil Research: JEOR, Jul/Aug 2003 by Kirimer, N, Tabanca, N, Ozek, T, Baser, K H C, Et al

Received: February 2001

Revised: April 2001

Accepted: June 2001

Abstract

S. argyrea P.H. Davis, S. armeniaca Bornm., S. hololeuca Boiss. et Heldr. Apud Bentham, S. stricta Boiss. et Heldr. Apud Bentham and S. taurica Stephan ex Willd., are endemic species in Turkey. Water-distilled essential oils from the flowering spikes of these plants were analyzed by GC/MS . Major components characterized in the oils of S. argyrea, S. armeniaca, S. hololeuca and S. stricta were [beta]-pinene (20%, 39%, 35% and 30%, respectively) and [alpha]-pinene (14%, 17%, 16% and 13%, respectively). The oil of S. taurica was characterized by [alpha]-bisabolol (10%) and [alpha]-pinene (9%) as main constituents.

Key Word Index

Sideritis argyrea, Sideritis armeniaca, Sideritis hololeuca, Sideritis stricta, Sideritis taurica, Lamiaceae, [alpha]-pinene, [beta]-pinene, [alpha]-bisabolol.

Introduction

The genus Sideritis (Lamiaceae) is represented in Turkey by 46 species, and altogether 53 taxa, 39 taxa being endemic (1-6). Several Sideritis species are used in folk medicine. Pharmacological and antimicrobial activities of Sideritis species have been reported (7).

The oil of S. argyrea was reported to exhibit antimicrobial activity (8). The extracts of some Sideritis species of Turkey, including S. argyrea, have been shown to have antibacterial activity (9). Six Sideritis species, including S. argyrea, have been reported to have antiinflammatory activity against carrageenan-induced oedema in mice (10). The oil of S. argyrea was previously reported to contain [alpha]-pinene as main constituent (11). Diversity and antifeedant activity of diterpenes from some Turkish Sideritis species have also been reported (12).

Here, we report on the oil composition of S. argyrea P.H. Davis, S. armeniaca Bornm., S. hololeuca Boiss. et Heldr. Apud Bentham, S. stricta Boiss. et Heldr. Apud Bentham and S. taurica Stephan ex Willd., which are endemic species in Turkey. S. argyrea is locally known as "Esekcayi" and "Aci cay" in Antalya, Alanya, while S. stricta is locally known as "Dag cayi" and "Tosbaga otu" in Antalya. These species are used as herbal tea in the areas where they grow. The former two are traded in the Antalya province.

This is the first report on the oil compositions of S. armeniaca, S. hololeuca, S. stricta and S. taurica.

Experimental

Plant material: Aerial parts of the plants were collected from the localities shown in Table I. Voucher specimens are kept at the Herbarium of the Faculty of Pharmacy of Anadolu University in Eskisehir, Turkey (Acronym: ESSE).

Oil isolation: Plants materials were hydrodistilled for 3 h using a Clevenger-type apparatus. Percentage yields of the oils calculated on moisture-free basis were as follows: S. argyrea (0.45%), S. armeniaca (0.54%), S. hololeuca (0.02%), S. stricta (0.63%) and S. taurica (0.08%).

Analysis: The essential oils were analyzed by Gas Chromatography/Mass Spectrometry systems. GC/MS analysis was carried out using a Hewlett-Packard GCD system. Innowax FSC column (60 m x 0.25 mm, 0.25 [mu]m film thickness) was used with helium as a carrier gas (1 mL/min). GC oven temperature was kept at 60[degrees]C for 10 min and programmed to 220[degrees]C at a rate of 4[degrees]C/min and then kept constant at 220[degrees]C for 10 min to 240[degrees]C at rate of 1[degrees]C/min. Alkanes were used as reference points in the calculation of relative retention indices (RI). Split ratio was adjusted at 50:1. The injector temperature was at 250[degrees]C. MS were taken at 70 eV. Mass range was from m/z 35-425. Library search was carried out using Wiley GC/MS Library and TBAM Library of Essential Oil Constituents. Relative percentage amounts of the separated compounds were calculated from Total Ion Chromatograms by the computerized integrator.

Results and Discussion

Sideritis is an important genus in Turkey because of the high percentage of endemism and the wide use of its members as herbal tea. Those Sideritis species used as herbal tea generally contain [alpha]- and [beta]-pinene in their oils (13). Although Sideritis species are poor in essential oil, dried Sideritis flowers impart a pleasant characteristic aroma to infusions which are consumed especially in southern Turkey.

The results of GC/MS analyses of the oils are given Table II. Eighty-six compounds were characterized in the oil of S. argyrea making up 95.4% of the oil. The oil of S. armeniaca, yielded 86 compounds representing 93.7% of the oil. In the oil of S. hololeuca 47 compounds were characterized representing 93.2% of the oil. Eighty-seven compounds were identified in the oil of S. stricta, representing 92.7% of the oil. In the oil of S. taurica, 91 compounds were characterized representing 90.8% of the oil. Major components characterized in the oils of S. argyrea, S. armeniaca, S. hololeuca and S. stricta were [beta]-pinene (20%, 39%, 35% and 30%, respectively) and [alpha]-pinene (14%, 17%, 16% and 13%, respectively). The oil of S. taurica was characterized with [alpha]-bisabolol (10%) and [alpha]-pinene (9%) as major constituents.