Essential Oil Composition of Juniperus wallichiana from North Western region of Kumaun Himalaya

Abstract

The essential oils isolated from leaves, berries and twigs of Juniperus wallichiana collected from areas near Milam glacier were dominated by sabinene (46.7%), besides α-pinene (6.6%) and terpinen-4-ol (6.5%) in leaf oil, while the berry oil contained higher content of sabinene (50.6%) and α-pinene (8.1%). The twig essential oil contained α-cadinol (9.8%), terpinen-4-ol (8.4%), oplopanone (8.0%) and epi-α-cadinol (5.0%) and almost no monoterpenes. Indian oils revealed a higher percentage of monoterpenoids in the leaf and berry oils while the twig oil contained sesquiterpenoids as major compounds.

Key Word Index

Juniperus wallichiana, Cupressaceae, essential oil composition, sabinene.

Introduction

Juniperus wallichiana Hook. f. et Thorns, ex Brandis, also known as black Juniper, belongs to family Cupressaceae and is a high altitude shrub which occurs at 3,000 to 4,400 m and is distributed in Western Himalayan region (1,2). Juniperus wallichiana is used as incense in Buddhist temples (2). The Indian taxonomists place/, wallichiana Hook. f. et Thorns, ex Brandis synonyms withjuniperus indica Bertol. andjuniperus pseudosabina Fischer et Meyer (2). However, Adams in recent publications on Junipers clearly separates these three taxa as distinct species based on results of both the oil and their DNA studies (3). Farjon (4) has reported/, wallichiana as a synonym of the /. indica but whether these are conspecific is still an open question.

The systematics oí Juniperus wallichiana of the eastern hemisphere has revealed sabinene (31.8%), a-pinene (9.4%), terpinen-4-ol (4.5%) and nezukol (4.0%) as the major constituents (3) while a-pinene (52.1%), cedrol (10.7%) and sabinene (5.8%) have been reported from/, pseudosabina oil (3). Adams et al. (5) reported chemical variations in the leaf oil of/. índica Bertol. from Nepal widi sabinene (19.4^31.3%), ß-diujone (4.5-25.8%), terpinen-4-ol(3.7-13.0%)andtron.s-sabinyl acetate (7.6-24.3%) as the principal constituents. Thus, the above reports confirm that all the diree species viz.,/. wallichiana, J. indica and/, pseudosabina have distinct terpenoid compositions and cannot be marked as synonyms of each otiier.

Adams has reported the / wallichiana oil widi moderate amount of sabinene from East Nepal (3). We compare the chemical composition of/, wallichiana leaf, berry and twig oils collected from near glacier of north western region of Kumaun Himalaya.

Experimental

Plant material: Juniperus wallichiana samples from two shrubs were collected from Bilju village near Milam glacier (3,200 m). The identification of plant material was done separately from Botany Department, Kumaun University and compared with herbarium records of Botanical Survey of India, Dehradun. The voucher specimens CSC 1001- 1002 have been deposited in Phytochemistry lab., Chemistry Department and Botany Department, Kumaun University, Nainital.

Isolation of oils: The plant materials (1.4 kg : leaves; 1.8 kg : berry and 1.2 kg : twig) were subjected to steam distillation for 2 h obtaining 5 L water distillate each. The distillate was saturated with NaCl and die oil was extracted with hexane and mediylene chloride. The organic phase was dien dried over anhydrous Na2SO4 and the solvent distilled off in a thin film rotary vacuum evaporator at 3O0C. The oil yield (calculated as oil w/w of fresh extracted parts) of leaf, berry and twig oils were 1.3%, 0.27% and 0.25%, respectively.

Essential Oil Analysis: The oil samples were analyzed by gas chromatography (GC) and gas chromatography/mass spectrometry ( GC/M S) . The oils were analyzed by using Nucon 5765 gas Chromatograph (Btx-5MS column, 30m ? 0.32 mm, FID), split ratio 1:48, N2 flow of 4 kg/cm2 and ThermoQuest Trace GC 2000 interfaced widi Finnigan MAT Polaris Q Ion Trap Mass spectrometer fitted with Rtx-5 MS (Restek Corp.) fused silica capillary column (30 m ? 0.25 mm; 0.25 pm film coating) . The column temperature 60°-2 210°C was programmed at 3°C/ min using He as carrier gas at 1.0 mL/ min. The injec tor temperature was 2100C, injection size 0.1 pL prepared in n-hexane, split ratio 1:40. MS were taken at 70 eV with mass range of m/z 40-450. Characterization was done on die basis of Retention Index, Library MS Search (NIST & Wiley), by comparing with the mass spectral literature data (6) and NMRof isolates such as terpinen-4-ol, a-terpineol, bornyl acetate, germacrene D-4-ol, epi-a-cadinol, a-cadinol and manool. The relative amounts of individual components were calculated based on GC peak areas without using correction factors.

Results and Discussion

The GC and GC/MS of die oils from/, wallichiana show presence of more than 80 compounds, of which 68, 55 and 74 compounds representing 91.4%, 99.6% and 72.0% in the leaf, berry and twig oils, respectively have been identified. The leaf and berry oils were dominated by sabinene (46.7%), a-pinene (6.6%) and terpinen-4-ol (2.2%). The analysis revealed diat the monoterpenoids were almost exclusive constituents of the / wallichiana leaf oil with sabinene as the major constituent. The total chemical compositions of the leaf, berry and twig essential oils are given in Table I.