Chemical Constituents of Essential Oil of Lantana camara Linn. Leaves

The determination of the chemical profile of essential oil of the leaves of Lantana camara Linn. was undertaken in this study. Essential oil was extracted from the dried leaf sample using hydro distillation method. Gas Chromatograph coupled with Mass Spectrometer (GC-MS) was used for chemical analysis of the extracted essential oil. Eighteen constituents were identified, representing 100% composition of the oil. The constituents were mainly monoterpenes and sesquiterpenes. The major constituents were found to be caryophllene oxide (21.75%), (-) spathulenol (14.95%), D-nerolidol (10.39%) and (-) -β-caryophyllene (9.90%). The yield of essential oil obtained was 0.19%. Some of the identified constituents of the essential oil have proven pharmacological activities, uses in food, drink and cosmetic industries. The essential oil of L. camara leaves is worth exploiting for use by relevant industries.


INTRODUCTION
Lantana camara is a native of the American tropics. It has become naturalized in suitable habitats in tropical regions worldwide. L. camara is an erect or subs cadent aromatic branching shrub with prickles. It belongs to the Verbenaceae family. The stems are quadrangular, armed with hooked prickles. The leaves are simple, opposite and oval-shaped with serrated margins and green in color. The flowers are born in flat-topped clusters, small, tubular and white, yellows, orange, red or purple. The fruits are produced in clusters, green in color and turn black when ripe (Ivan, 2003).
L. camara Linn. has several uses, different parts of the plant are used for medicinal and non-medicinal purposes. It has been listed among the useful plants of West Tropical Africa by Burkill (2000). In Nigeria, the leaves have been used in folk medicine as antibiotic, febrifuge, for treatment of chest diseases and high blood pressure (NNMDA, 2006).
This study was undertaken to determine the chemical profile of the essential oil of the leaves of L. camara Linn.

Essential oil extraction:
The collected leaves of the plant L. camara were air-dried at room temperature under shade for 28 days. The dried leaves were pounded to powdery form using local mortar and pestle. The powdery form was then subjected to hydro distillation. The extracted essential oil was dried over anhydrous sodium sulphate. The percentage yield was calculated based on the dry weight of the leaf.

Chemical analysis of essential oil:
The chemical analysis of the oil was carried out on a GC-MS instrument (GCMS-QP 2010 Plus Shimadzu, Japan). The analysis was done under the following conditions: RTX-5 ms (30 m×0.25 mm; 0.25 µm film thickness) fused-silica capillary column; programmed column oven temperature 60°C (2 min), 180°C (3 min) and 280°C (5 min); injection temperature 250°C; carrier gas: helium; flow control mode: linear velocity of 36.2 cm/sec; injection mode; split; split ratio: 50.0; pressure: 56.2 pka; total flow: 53.2 mL/min; column flow: 0.99 mL/min; purge flow: 3.0 mL/min; Ion source temperature: 200°C; interface temperature: 25°C; solvent cut time: 2.50 min; detector gain mode: relative; detector gain: 0.00 kv; threshold: 2000. The quantitative data of the specific constituents of volatile  oil were obtained by peak area normalization using a GC/FID. The identification of specific components was done by comparison of both mass spectra and GCretention data with authentic compounds previously analyzed and stored in the data system. Other identifications were carried out by comparison of the mass spectra with those existing in the data system libraries and cited in the literature (Adams, 2007;Mclafferty et al., 1974;NIST, 2005).

DISCUSSION AND CONCLUSION
The serrated leaves of Lantana camara are aromatic and result has shown that they contain highly volatile oil. This oil is responsible for its essence. The extracted essential oil was bright yellow in color. A yield of 0.19% was obtained.
Caryophllene oxide has been reported as having analgesic, anti-inflammatory activity and antifungal activity against dermatophytes (Yang et al., 1999;Chavan et al., 2010). It is also well known as a preservative in food, drugs and cosmetics (Yang et al., 1999).
Terpenes such as nerolidol, eucalyptol have been used as chemical enhancer to improve skin penetration for transdermal delivery of therapeutic drugs (Denise et al., 2005). D-nerolidol is also used as a food flavoring agent.
(-) -β-Caryophyllene, a natural bicyclic sesquiterpene that is a constituent of many essential oil especially clove oil, rosemary, hops, among others (Ghelardini et al., 2001;Glenn, 1993). (-) -βcaryophyllene has been demonstrated to have antiinflammatory effects in mice (Gertsch et al., 2008). It is an FDA approved food additive and ingested daily with food. It is the first dietary cannabinoid.
Spathulenol has an earthly-aromatic odor and a bitter herbal flavor. It has been found in various types of Artemisia (Juell, 1976). Spathulenol is used as fragrance and flavoring agents for drinks.
α-Caryophyllene (α-humulene) is a naturally occurring monocyclic sesquiterpene found in essential oil of Humulus lupulus (hops) from which it derived its name (Glenn, 1993). The anti-inflammatory effects of α-humulene has been reported (Fernandes et al., 2007). α-Pinene oxide is used in fragrance industry. 1-Naphthalenol (1-Naphthol) is a precursor to a variety of insecticides including carbaryl and pharmaceuticals including nadolol (Meeker et al., 2006;Gerald, 2005). Nadolol is a non-selective beta blocker used in the treatment of high blood pressure, migraine headaches and chest pain.
Results from this study have shown that the essential oil of L. camara leaves contains compounds with proven pharmacological effects. The continued demand for preparation of synthetic flavorings and fragrances for use in pharmaceutical, food, drink and cosmetic industries makes the essential oil of L .camara worth exploiting for use by relevant industries.

ACKNOWLEDGMENT
Dr. Zakari Ladan of National Research Institute of Chemical Technology, Basawa, Zaria, Kaduna state, Nigeria is acknowledged for his contribution and technical assistance to this research study.