Essential Oil Constituents of Leaves of the Male and Female Shrubs of Juniperus chinensis L. from Isfahan

     Leaves of the male and female shrubs were collected in May 2004 from populations growing in Isfahan (Iran). The shrubs were identified by the Botany Department of the Faculty of Sciences at the University of Isfahan (Iran). Voucher specimens of the leaves (no.1773) were deposited in the Herbarium of the Pharmacognosy Department, Faculty of Pharmacy and Pharmaceutical Sciences at the Isfahan University of Medical Sciences (Iran).

2.2. Isolation of the essential oil

     Powdered air-dried leaves of the male and female shrubs were separately hydrodistilled for 4 h. Pale yellow oils (1.29% and 0.66% v/w) were obtained having the refractive indices of 1.4475 and 1.4476 measured at 25 °C.

2.3. GC analysis

     Gas chromatographic determinations were run on a Perkin Elmer 8500 instrument using a BP1 capillary column (30 m×0.25 mm; film thickness: 0.25 μm). The carrier gas was nitrogen with a flow rate of 2 ml/min. The oven temperature was programmed from 60-275 °C at 4 °C/min. Injector and detector temperatures were 275 °C and 280 °C, respectively.

2.4. GC/MS analysis

     Analysis of the oils was performed on a Hewlett Packard 6890 GC/MS instrument under the following conditions: Injection of 0.1 μl samples, HP-5 MS capillary column (30 m×0.25 mm ; film thickness 0.25 μm); carrier gas He, flow rate 2 ml/min., injector temperature 250 °C, temperature program: 60-275 °C at 4 °C/min.; mass spectra: electronic impact, ionization potential 70 eV, ion source temperature 250 °C, ionization current 1000 μA, resolution 1000, and mass range 30-300.

    Identification of the constituents was based on computer matching against the library spectra (Library Database Wiley 275), their retention indices with reference to an n-alkane series in a temperature programmed run, interpreting their fragmentation pattern and comparison of the mass spectra with the literature data [4].

3. Results and discussion

    Forty-one constituents in the male shrub leaf oil (representing 96.2% of the total oil) and thirty nine components in the female shrub leaf oil (representing 95.4% of the total oil) were identified (Table 1). Bornyl acetate (26.1%), sabinene (18.3%), trans-sabinyl acetate (11.1%), myrcene (9.2%), limonene (6.1%), elemol (5.5%), α-cadinol (2.3%), δ-cadinene (2.2%), α-thujone (1.6%), α-pinene (1.3%) and α-muurolol (1.1%) were the main constituents of the leaf oil of male shrub; while the major constituents of leaf oil of the female shrub were sabinene (18.0%), bornyl acetate (12.3%), carotol (11.4%), elemol (9.9%), myrcene (8.8%), α-pinene (6.4%), α-cadinol (4.8%), limonene (3.9%), δ-cadinene (3.4%) and α-muurolol (2.7%). In a previous work which has been done by other workers, ethyl acetate was reported to be one of the major constituents of leaf oils of Juniperus chinensis growing in China (three samples: 20.65%, 12.55% and 19.6%), but it was absent in the leaf oil of Juniperus chinensis var. kaizuca [5]. The lattermentioned compound could not be detected in our analyzed leaf oils as well. As in case of of J. chinensis cv. pyramidalis and J. chinensis var. kaizuca leaf oils, our examined leaf oils did not contain the cedrene/cedrol components [5].

    The amount of essential oil obtained from the leaf of the male shrub (1.29% v/w) was about twice the amount of that produced by the leaf of the female shrub (0.66%). As it is obvious from Table 1, the relative percentage production of sabinene and myrcene in both leaf oils is about the same, while the production of bornyl acetate by the leaf of the male shrub (26.1%) is higher than that produced by the leaf of the female shrub (12.3%). On the other hand, the leaf of the male shrub produces 11.1% trans-sabinyl acetate, while the leaf of the female shrub doesn't produce this monoterpenoid.

Table 1. Percentage composition of leaf essential oils of the male and female shrubs of Juniperus chinensis from Isfahan.

 t = trace (less than 0.1%)

Acknowledgement

    We are grateful to Mr. Akbar Akoochekian for his help to prepare the voucher specimens of the plant materials and Mrs. Armita Jamshidi for her help in analyzing the oil samples by GC and GC/MS methods.