Chemical Composition of Essential Oil of Lantana indica Roxb. Leaves

Journal of Essential Oil Research: JEOR, Nov/Dec 2006 by Akhtar, M Sohail, Ali, Mohammed, Mir, Showkat R

Abstract

A steam-distilled essential oil obtained from the leaves of Lantana indica Roxb. (Verbenaceae), infesting large areas in India and used variously in Indian system of medicine, was analyzed by capillary GC and GC/MS. Quantitatively, the oil contained about 42% monoterpenes and 51% sesquiterpenes. The predominant component was α-humulene (17.8%) followed by δ-3-carene (15.6%), sabinene (14.8%), (E)-nerolidol (9.2%), β-selinene (8.6%) and globulol (7.7%).

Key Word Index

Lantana indica, verbenaceae, essential oil composition, α-humulene, δ-3-carene.

Introduction

Lantana, belonging to family Verbenaceae, is a genus of about 150 species, mostly native to subtropical and tropical America, but a few taxa are indigenous to tropical Asia and Africa. The genus is a difficult one to classify taxonomically since species are not stable as hybridization is widespread (1-3). Lantana indica Roxb. is a wild shrub, native to India, with bunches of light purple flowers and opposite and whorled pubescent leaves. It is regarded both as notorious weed and a popular ornamental garden plant and is used as a sudorific, intestinal antiseptic, diaphoretic, and in treatment of tetanus and rheumatism and malaria in Indian medicine (2-5). Phytochemically, the plant revealed the presence of several triterpenes (5-7) and sterols (8).

Given that there are large areas infested with this plant, it is reasonable to consider if large scale use could be made of its biomass. The fact that there are few reports of analysis of essential oil of L. indica in comparison to other species (3,9-11) lured us to examine its leaf volatile oil. As a part of our investigation on aromatic and medicinal plants of India, we describe in this communication the chemical composition of essential oil of L. indica by means of modern techniques.

Experimental

The fresh leaves of L. indica were collected from Herbal Garden, Hamdard University, New Delhi, India, in March 2004. The plant material was identified and authenticated by M.P. Sharma, taxonomist, Department of Botany, Hamdard University. A voucher specimen (No. DBT-04-02) was retained in the departmental Herbarium for further reference.

Oil isolation: The fresh leaves (900 g) were chopped and hydrodistilled in an all glass apparatus according to British Pharmacopoeia 1988. The pale yellow oil possessed pleasant and characteristic odor. It was dried over anhydrous sodium sulfate and stored at 4°C in the dark. The yield was 0.33% (w/v) on the dry weight basis.

GC analysis: The GC analysis of the oil was performed on a Perkin-Elmer Auto XL system, using PE-5 capillary column (50 m x 0.32 mm, film thickness 0.25 µm). the carrier gas used was hydrogen at 10 psi flow pressure; temperature programmed from 100°-280°C at 3°C/min; injector temperature was 220°C and injection volume was 0.1µl. Detector used was FID; detector temperature 290°C. Quantitative data was obtained from FID area percentages without the use of correction factors.

GC/MS analysis: Analytical GC/MS was carried out on a Shimadzu QP-2000 instrument at 70 eV and 250°C. GC column: Ulbon HR-1, fused silica capillary (50 m x 0.25 mm, film thickness 0.25 µm). The carrier gas was He with flow rate of 2 mL/min. The initial temperature was 100°C for 6 min and then heated at a rate of 10°C/min to 250°C.

Identification: Most constituents were identified by GC, comparing their retention indices with those of authentic standards available in the authors' laboratory or with retention indices in the close agreement with the literature (12,13). Further identification patterns were achieved by GC/MS. Other constituents were tentatively identified by means of GC/MS. The fragmentation patterns of mass spectra were compared with those stored in spectrometer database using NBS 54 K.L and Wiley in-built libraries and with those published in the literature. (12-19)

Results and Discussion

The volatile components of L. indica leaves, their percentage composition and retention indices are listed in Table I. Components are arranged in order of GC elution on ulbon HR-1 fused silica capillary column. Analysis of oil by GC and GC/MS resulted in complete identification of 25 components of the total 28 detected comprising 99.7% of total volatiles. Quantitatively, the oil was characterized by 42% and 51% monoterpenes and sesquiterpenes, respectively. Three components, comprising 2.1% of the total, were tentatively identified on the basis of their mass spectra. Among 11 monoterpenes, there were eight monoterpenes hydrocarbons (39.1%) and three oxygenated monoterpenes (3%) and out of 10 sesquiterpenes, there were seven sesquiterpene hydrocarbon (31%) and three oxygenated sesquiterpenes (19.6%). Four aliphatic constituted 4.9% of total volatiles. The characteristics components of the oil were found to be α-humulene (17.8%), δ-3-carene (15.6%), sabinene (14.8%), (E)-nerolidol (9.2%) and globulol (7.7%).

The notable presence of pleasant smelling selinene isomers such as β-selinene (8.6%) and α-selinene (2.5%), is an important fact as these are valuable aroma volatiles, frequently encountered in celery oil (20) and promises an unexplored potential of the oil of this wide spread biomass, infesting large areas in India.