Chemical Composition of the Essential Oil from the Leaves of Curcuma zedoaria Rosc. of Indian Origin

Journal of Essential Oil Research: JEOR, Jan/Feb 2005 by Garg, S N, Naquvi, A A, Bansal, R P, Bahl, J R, Kumar, Sushil

Abstract

The essential oil, which was produced by hydrodistillation of Curcuma zedoaria (Zingiberaceae) leaves, was investigated by GC and GC/MS. Twenty-three compounds were identified, accounting for 75% of the oil. The oil of C. zedoaria was made up mainly of mono- and sesquiterpenoids, monoterpene hydrocarbons (2.3%), oxygenated monoterpenes (26%), sesquiterpene hydrocarbons (38%), and oxygenated sesquiterpenes (13.5%). α-Terpinyl acetate (8.4%), isoborneol (7%), dehydrocurdione (9%) and selina-4(15),7(11)-dien-8-one (9.4%) were the major constituents of the leaf oil.

Key Word Index

Curcuma zedoaria, Zingiberaceae, essential oil composition.

Introduction

Curcuma zedoaria, family Zingiberaceae, a species growing wild in the eastern Himalayas and cultivated throughout India, Ceylon and China. The plant closely resembles Curcuma longa in appearance and grows to a height of about 0,4 m and bears green leaves with brownish purple veins. The rhizomes of C. zedoaria are used in the traditional system of medicine for the treatment of cervical cancer. The essential oil of C. zedoaria exhibits antimicrobial activity against Staphylococcus aureus, Vibrio comma and Escherichia coli, and also shows antimutagenic activity against benzo(α)pyrene-induced mutations in the Selmonella/microsomal system (2). The constituents of C. zedoaria rhizome oil has been investigated extensively and recognized as a rich source of terpenoids (3-11). Much of the work has been focused on C. zedoaria rhizome oil produced in Vietnam (12-14), Japan (15-16) and China (17-18). Very little work has so far been reported on

the oil of rhizomes (19-20) or leaves of plants grown in India. The present authors wish to report here the GC/MS analysis of the C. zedoaria leaf oil.

Experimental

Plant material: Fresh leaves of C. zedoaria Rose, were collected from the Central Institute of Medicinal and Aromatic Plants' research farm, Lucknow. A voucher specimen was deposited at the Institute's Herbarium. The fresh plant material (5 kg) was cut into pieces and hydrodistilled for 4 h using a Clevenger-type apparatus. The oil obtained was dried over anhydrous sodium sulfate in a yield of 0.2% v/w on fresh weight basis.

Oil fractionation: The oil (10 inL) was chromatographed over SiO^sub 2^ (200 g) column eluting with hexane and various proportion of hexane-diethyl ether yielding 20 fractions (100 mL). These fractions were combined according to their composition as assessed by TLC, rechromatographed over a SiO^sub 2^ column from which pure constituents were obtained.

Chromatographic analysis (GC and GC/MS): The GC on the oil sample was performed using a Varian gas Chromatograph (F.D.) Model CX-3400 under the following conditions: carrier gas hydrogen, injector and detector temperatures 220°C and 225°C, respectively, using a capillary column (Supelcowax-10, 30 m × 0.30 mm, film thickness 0.2 µm), and oven temperatures programmed from 80°-150°C at 5°C/min, then to 215°C at 7°C/min. The area percentage was obtained on Varian 4400 integrator. GC/MS was recorded on a Shimadzu QP-2000 instrument at 70 eV with a capillary column (50 m × 0.25 mm) OV-1, film thickness 0.25 µm. The carrier gas used was helium at a flow rate 2 mL/min and the column was programmed as follows: 100°C (6 min), 100°-250°C at 10°C/min.

Identification of the constituents: The constituents were identified by comparing their GC retention time with those of authentic samples as well as of the components of other oils which had been identified earlier and by matching their GC/MS fragmentation pattern with those reported in the literature (21,22) and the library established by the authors.

NMR methods: ^sup 1^H-NMR spectras were recorded on Bruker DRX- 300 (300 MHz) and ^sup 13^C-NMR was recorded on 75 MHz in CDCl^sub 3^. Chemical shifts were recorded in ppm (δ) relative to (CH^sub 3^)^sub 4^Si, (TMS; δ-0.0 ppm).

Dehydrocurdione (1): ^sup 1^H-NMR (300 MHz, CDCl^sub 3^): δ 5.12 (1H, t,J=7.5Hz, H-1), 3.23 (1H, d, J=18 Hz, H-9a), 3.18 (1H, d, J=18Hz, H-9b), 3.12(1H,d,J=11Hz, H-6a), 2.85(1H, d, J=11Hz, H-Gb), 1.85 (3H,s,H-13), 1.80 (3H,s,H-12), 1.60 (3H,d, J=1.5Hz,H-14), 0.97 (3H,dJ=7Hz,H-15).

Selina-4(15),7(11)-dien-8-one(2): ^sup 1^H-NMR (300 MHz1CDCl^sub 3^) : δ 4.75 (1H brs,H-15a), 4.55 (1H, br s, H-15b),2.2 (2H,s,H-9), 1.95 (3H,s,H-12), 1.75(3H,s,H-13), 1.68 (1H.brd, H-5), 0.75 (3H,s,H-14), ^sup 13^C-NMR (75 MHz ,CDCl^sub 3^) δ 203.7 (C-8), δ 149.0 (C-4), δ 142.6 (C-11), δ 131.5 (C-7), δ 106.9 (C-15), δ 57.6 (C-9), δ 46.99 (C-5), δ 41.20 (C-3), δ 38.20 (C-10), δ 36.80 (C-1), δ 29.20 (C-6), δ 23.17 (C-2 & C-12), δ 22.25 (C-13), δ 17.26 (C-14).

Results and Discussion

Under the auspices of a screening program to search for new sources of essential oils, the leaves of C. zedoaria yielded pale yellow oil (0.2% v/w) on hydrodistillation. This oil was examined by GC and GC/MS. In India no work has so far been reported on the leaf oil of C. zedoaria, and a very little work was reported on the rhizome oil. Ethyl p-methoxycinnamate, a major antifungal principle, was isolated and identified from the rhizomes of C. zedoaria by Gupta et al. (1976) and later on by Joshi et al. (1989). Twenty-three constituents were identified representing 75% of the oil and are shown in Table I. The major constituents of the oil, which were isolated in pure form and confirmed by 1H-NMR, were isoborneol, a-terpinyl acetate, dehydrocurdione and selina 4(15),7(11)-dien-8-one. Ethyl p-methoxycinnamate, which was isolated and identified from the rhizome oil, was not found in the leaf oil. This is the first report of the investigation of C. zedoaria leaf oil in India.