ABSTRACT

In this study, the chemical compositions of the leaves, berries and twigs essential oils of J. oxycedrus L. subsp. oxycedrus, collected in Turkey, were determined. The oils were analyzed by GC and GC-MS. 15-21 volatile compounds were identified of the leaves, berries and twigs essential oils representing 82.4-98.0% of the total oils. The essential oils were obtained from leaves, berries and twigs by yielding 0.02%, 2.12% and 0.01%, resp. The major compounds were determined manoyl oxide (32.8%) and caryophyllene oxide (11.9%) in leaf oil, myrcene (44.6%), α-pinene (19.9%) and germacrene D (15.5%) in berry oil, manoyl oxide (35.4%) and caryophyllene oxide (16.8%) in twig oil.

INTRODUCTION

The genus Juniperus L. belongs to the Cupressaceae family, representing about 70 species all over the world, and widely distributed throughout the forests of the temperate and cold regions of the northern Hemisphere, from the far north to the Mediterranean. Juniperus L. is represented in Turkey by 7 species and 14 taxa. Juniperus oxycedrus has two subspecies – subsp. oxycedrus and subsp. macrocarpa – in Turkey (1,2).

Several studies have reported the chemical composition of leaves, berries and twigs and their the essential oils (EOs) of J. oxycedrus L. subsp. oxycedrus (Table 1) (3-16).

In the present work, leaves, berries and twigs EOs of J. oxycedrus subsp. oxycedrus were investigated to chemical compositions of plants collected from Eskişehir: Hekimdağ in Turkey. In the study, the oils were obtained by hydrodistillation. The oils were analyzed by gas chromatography (GC) and gas chromatography/ mass spectrometry (GC/MS).

EXPERIMENTAL

Plant material

J. oxycedrus subsp. oxycedrus was collected from Eskişehir: Hekimdağ, in Turkey on 15 March 2015. Voucher specimens are kept at the Herbarium of Pharmacy Faculty, Anadolu University, Turkey (ESSE 14987).

Isolation of essential oils

The oils were obtained by hydrodistillation for 3 hours using Clevenger apparatus. The essential oils were stored at 4°C in the dark until analyzed. The oils were analyzed by capillary GC and GC/MS using a Agillent GC-MSD system.

Gas Chromatography (GC) and Gas Chromatography - Mass Spectrometry (GC/MS) analysis

The GC/MS analysis was carried out with an Agilent 5975 GC-MSD system. Innowax FSC column (60 m x 0.25 mm, 0.25 mm film thickness) was used with helium as carrier gas (0.8 mL/min). GC oven temperature was kept at 60°C for 10 minutes and programmed to 220°C at a rate of 4°C/min, and kept constant at 220°C for 10 minutes and then programmed to 240°C at a rate of 1°C/minutes. Split ratio was adjusted 40:1. The injector temperature was at 250°C. MS were taken at 70 eV. Mass range was from m/z 35 to 450.

The GC analysis was carried out using an Agilent 6890 N GC system. In order to obtain the same elution order with GC/MS, simultaneous injection was done by using the same column and appropriate operational conditions. FID temperature was 300°C.

Identification of compounds

The components of essential oils were identified by comparison of their mass spectra with those in the Baser Library of Essential Oil Constituents, Wiley GC/MS Library, Adams Library, MassFinder Library and confirmed by comparison of their retention indices. Alkanes were used as reference points in the calculation of relative retention indices (RRI). Relative percentage amounts of the separated compounds were calculated from FID chromatograms.

RESULTS AND DISCUSSION

The EOs were obtained from leaves, berries and twigs by yielding 0.02%, 2.12% and 0.01%, respectively. The list of compounds identified in the hydrodistilled leaves, berries and twigs of J. oxycedrus L. subsp. oxycedrus with their relative percentages and retention indices are given in Table 2.

In our study, 15-21 volatile compounds were identified of the leaves, berries and twigs EOs representing 82.4-98.0% of the total oils. Twig oil composition was not found in previous studies. Manoyl oxide (35.4%) and caryophyllene oxide (16.8%) were identified as major contituents in twig oil (Figure 1), myrcene (44.6%), α-pinene (19.9%) and germacrene D (15.5%) in berry oil (Figure 2), manoyl oxide (32.8%) and caryophyllene oxide (11.9%) in leaf oil (Figure 3).

As seen in previous studies Table 1, the leaf oils were characterized by the presence of α-pinene, t-pinocarveol and limonene as main contituents (3-10). But, in our study, the occurrence of manoyl oxide and caryophyllene oxide was interesting. While some contituents like α-pinene and myrcene were found in berry oil samples (11-15), germacrene D was only in one sample (16).

Medini et al. have reported α-pinene, germacrene D, myrcene, abietadiene and cis-calamenene as main constituents of the EOs of the berries of Juniperus oxycedrus L. subsp. rufescens (L.K.) and Juniperus oxycedrus L. subsp. macrocarpa (S. & M.) Ball. (17).

Sezik et al. have reported manoyl oxide (21.9%) and α-pinene (11.3%) as main constituents in leaf oil of J. oxycedrus subsp. macrocarpa from Eskişehir (18).

Variability of the oil composition in different populations of the same plant species might be attributed mainly to genetic diversity (19). Chemical composition and the main components of EOs J. oxycedrus have differentiate chemotype due to containing different climatic conditions of a large geographical diversity.