Volatile Constituents of Essential Oils Isolated from Different Parts of Alpinia calcarata Rosc.

Journal of Essential Oil Research: JEOR, Jan/Feb 2005 by Kaul, Pran N, Rao, Bhaskaruni R Rajeswara, Singh, Kamla, Bhattacharya, Arun K, Et al

Abstract

The essential oils isolated from different parts of Alpinia calcarata Rosc., (family: Zingiberaceae) growing in Hyderabad, south India, were analyzed by capillary GC and GC/MS. The oil yields were: flower 0.06%, leaf sheath 0.03%, stem 0.05% and root 0.18%. Sixty-two compounds accounting for 92.3-98.3% of the oils were identified. The flower oil contained β-pinene (12.5%), 1,8-cineole (12.8%) and (E)-methyl cinnamate (12.3%) as the major constituents. The important components of the leaf sheath oil were 1,8-cineole (23.2%) and humulene epoxide I (10.6%). The stem oil had β-pinene (11.2%) and 1,8-cineole (33.2%) as the major compounds. On the other hand, the root oil showed camphene (13.6%), 1,8-cineole (15.6%) and α-fenchyl acetate (37.6%) as the main constituents.

Key Word Index

Alpinia calcarata, Zingiberaceae, essential oil composition, 1,8-cineole, α-fenchyl acetate, β-pinene, (E)-methyl cinnamate, camphene.

Introduction

Alpinia calcarata Rosc. (family: Zingiberaceae), a medicinal plant is one of the seven species of Alpinia that occur in India, Myanmar, Indonesia, Thailand, New Guinea and the Bismark Archipelago (1,2). The rhizome extract of A. calcarata is used as an expectorant in the treatment of bronchitis and asthma; for purifying blood; stimulating digestion and improving voice (3). In addition, anti-inflammatory activity has also been reported (4). While the rhizome extract of A. calcarata has been reported to contain methyl cinnamate and 1,8-cineole as the major compounds (5), the rhizome and leaf oils contained camphene, β-pinene, 1,8-cineole and camphor as the major constituents (6). The physico-chemical characteristics of the oil have also been studied (7). However, the compositions of flower, leaf sheath, stem and root oils were not investigated earlier.

Experimental

Alpinia calcarata plants were grown on the Experimental Farm of Central Institute of Medicinal and Aromatic Plants, Field Station, Hyderabad, India. The experimental location experiences semi-arid tropical climate. The experiment was conducted when the plants were flowering. Samples of different plant parts (flower, leaf sheath, stem and roots) were harvested from healthy, well-grown, two-year-old plants. Freshly harvested samples (500 g each) in triplicate were subjected to hydrodistillation using a modified Clevenger-type glass apparatus for 4 h for isolation of oils separately from different parts. The oil samples were stored at 0°C in air-tight containers after drying them over anhydrous sodium sulfate for GC and GC/MS analyses.

GC: GC analyses of oil samples were performed employing Perldn Elmer gas Chromatograph (Model 8500) fitted with flame ionization detector (FID), GP-100printer-plotterandan electronic integrator, using a bonded phase fused silica capillary column BP-I (25 m × 0.5 mm, film thickness 0.25 µm) coated with polydimethylsiloxane and BP-20 column (25 m length × 0.5 mm, film thickness 0.25 µm) coated with Carbowax 20 M. Nitrogen at a flow rate of 40 mL/inin (linear velocity: 34 cm/s) and 10 psi inlet pressure was the carrier gas employed. Temperature programming was performed from 60°-220°C at 5°C/min for BP-I column and from 60°-200°C at 5°C/min for BP-20 column. The split ratio used was 1:80. The samples (0.1-0.2 µm) were injected neat.

GC/MS: GC/MS analyses of oil samples were carried out on a Hewlett Packard 5890 gas Chromatograph coupled to HP 5970 mass-selective detector (MSD) using a fused silica ultra performance cross linked methyl silicone HP-I column (50 m length × 0.2 mm, film thickness 0.25 µm). Temperature programming was done from 100°-280°C at 4°C/min. Helium was used as the carrier gas at 1 mL/min flow rate. Mass spectra were recorded over 40-400 amu range at 1 scan/s with ionization energy 70 eV and ion source temperature 250°C.

Identification of the compounds: Compound identification was done by comparing the retention indices of the peaks with those reported in literature (8-10), mass spectra of the peaks with literature data (9-11) and by peak enrichment with authentic standards, wherever possible. Percentage composition was computed from GC peak areas on BP-I column without applying correction factors.

Results and Discussion

The oil yields from different plant parts were: flower 0.06%, leaf sheath 0.03%, stem 0.05% and root 0.18%. Out of the 82 peaks, 62 constituents accounting for 92.3-98.3% of the oils were identified and are presented in Table I. There were similarities and differences amongthe oils. 1,8-CineoIe ( 12.8-33.2%) was one of the main components of all the oils. The flower oil was richerin β-pinene, (E)-methylcinnamate, Ct-gurjunene, β-caryophyllene, (E)-β-farnesene, β-caryophyllene oxide and bulnesol. The leaf sheath oil resembled that of leaf oil in its major constituents (6) and was richerin (Z)-allyl cinnamate, β-patchoulene, humulene epoxide I and β-bisabolol. The stem oil was richer in limonene, 1,8-cineole, camphor and α-terpineol. The root oil was richerin α-pinene, camphene, myrcene, borneol and α-fenchyl acetate. Variations in compositions of oils isolated from different plant parts of A. breviligulata and A. chinensis were reported from Vietnam (12,13). α-Fenchyl acetate was found to be one of the major constituents in the root oil of these two species (12,13) and rhizome oil of A. calcarata (6) also.