ESSENTIAL OIL STUDIES OF THE GENUS VITEX L. (VERBENACEAE)

Rogimon P.Thomas 1 , Asha Ramachandran 2 , Joby Paul 3 and Mahesh Mohan 4 . 1. Department of Botany,CMS College Kottayam (Autonomous),Kottayam,Kerala,India-686001. 2. Department of Botany,Government College Kottayam,Kerala,India. 3. Department of Botany,St.Thomas’ College (Autonomous),Thrissur,Kerala,India. 4. School of Environmental Sciences,Mahatma Gandhi University,Kottayam,Kerala ,India. ...................................................................................................................... Manuscript Info Abstract ......................... ........................................................................ Manuscript History Received: 15 March 2019 Final Accepted: 17 April 2019 Published: May 2019 The present study documents the characterization of essential oils obtained from different species of the genus Vitex L. of the family Verbenaceae. The oils were analyzed by gas chromatography-mass spectrometry (GC-MS). The coeffiecient of similitude, percentage yield and percentage area of occurrence were calculated. The study showed the richness of volatile oils in the genus Vitex.


Results:-
Using a conventional hydro-distillation process with a Clevenger apparatus, the leaves of Vitex trifolia, Vitex altissima, Vitex leucoxylon and Vitex negundo var. negundo yielded mobile, fragrant, pale yellow to light brown oil with pungent spicy fragrance.
Screening for desirable qualities like essential oil yield and composition becomes significant during characterization of essential oils. The essential oil isolated by hydro-distillation of leaves of different species of Vitex showed difference in yield based on the dry weight of the sample while the percentage of essential oil obtained also varied. The percentage yield of essential oil was found to be 0.7 (v/w) for Vitex leucoxylon, 0.4 (v/w) for Vitex altissima, 0.6 (v/w) for Vitex trifolia and 0.9 (v/w) for Vitex negundo var. negundo. The GC-MS pattern was distinctly different in all cases. The area percentage occurrence of the components in the leaf essential oil of selected Vitex sp. are also given. Number of compounds identified in Vitex trifolia is 16, Vitex altissima is 15, Vitex leucoxylon is 10 and Vitex negundo var. negundo is 9. The components identified by GC-MS analysis with their percentage composition are listed (Table 1, 2, 3 & 4 ).
The samples of the oil varied in colour from pale yellow to light brown. Vitex trifolia leaf essential oil was pale yellow, Vitex altissima leaf essential oil was brown, Vitex leucoxylon leaf essential oil was dark yellow and Vitex negundo var. negundo leaf essential oil was light brown in colour. The analysis of the oil samples showed a wide range of variation in their constituents.
The demand of novel anti-infective agents has led to the discovery of new sources of potential antimicrobials (Carson and Riley, 2003). Among them, the plants offer a wide range of molecules of immense value for the pharmaceutical industry. The results of the present study showed that the tested Vitex species contain higher percentage of some different constituents of essential oil and these can be applied to many therapeutic, perfumery and flavoring functions.

Conclusion:-
Essential oils are volatile aromatic compounds isolated from plants and the pharmaceutical properties of aromatic plants are partially attributed to essential oils. They are considered as the 'chemical weapons' since their compounds may have insect deterrent and antimicrobial properties. They are also regarded as 'plant pheromones' and oxygenated molecules of essential oils can serve as chemical messengers for cells. The present study was undertaken to examine the chemical composition of essential oil isolated from the leaves of Vitex species.
The results of the present study indicate that the selected Vitex species are capable of producing essential oils with variable antifungal activity. The essential oils of different species of Vitex showed difference in yield that varied from 0.4-0.9 (v/w). Vitex negundo var. negundo has the best essential oil yield of 0.9 (v/w). The total number of compounds detected in the essential oil from the leaves in four species of Vitex was 39 with a minimum of 9 components in each sample. Maximum number of compounds was found in Vitex trifolia while minimum in Vitex negundo var. negundo. The essential oil of the genus Vitex contains mostly sesquiterpenes. Along with that the essential oil also contains monoterpenes, alcohols and small amount of ketones.
The main components in the essential oil of Vitex species as established by GC-MS analysis were caryophyllene (Vitex trifolia), (+)-epi-bicyclosesquiphellandrene (Vitex altissima), Resorcinol (Vitex leucoxylon) and isoaromadendrene epoxide (Vitex negundo var. negundo). Caryophyllene was present as a common compound in all the species of Vitex with an area percentage range of 6.13% in Vitex leucoxylon and 38.36% in Vitex trifolia. The coefficient of similitude was found to be 2.56%. The chemical composition of all the species indicates that a number of chemicals are present in large percentage, which may find potential use in the pharmaceutical industry.
The type and composition of essential oil, yield and bioavailability and the concentration required to attain efficacy are all aspects that need to be considered for use as a therapeutic molecule. More efforts are necessary for an in vivo study of their single or combinational use as an alternative to antibiotics. Essential oils can also play an important role in determining and solving the taxonomic ambiguities involved in chemo-taxonomic classifications.