Chemical characterization of aroma compounds in essential oil isolated from "Holy Basil" (Ocimum tenuiflorum L.) grown in India

Ocimum tenuiflorum L. ("Holy Basil"/"Tulsi") is an indigenous Ayurvedic medicinal plant of India, widely distributed in tropical and warm temperate regions. Plant is well known for its enormous therapeutic activities and prevention against diseases. In the present study, thirty-two accessions of O. tenuiflorum germplasm collected from different regions of Northern India were evaluated for their essential oil content and composition. Essential oil obtained by hydrodistillation was analyzed by GC and GC/MS for aroma compounds. Essential oil content in O. tenuiflorum germplasm showed wide range of variation from 0.13 to 0.45 % on FWB. GC and GC/MS profile of O. tenuiflorum oil showed phenylpropanoids, mainly eugenol constituted the major proportion of essential oil. The range of major chemical constituents identified were eugenol (1.94-60.20 %), methyl eugenol (0.87-82.98 %), beta-caryophyllene (4.13-44.60 %), beta-elemene (0.76-32.41 %). Eugenol and methyl eugenol rich two chemotypes were identified in O. tenuiflorum germplasm. The accessions, IC583281, IC583285 and IC583322 were found to contain high eugenol content (> 55 %), while three accessions IC583279, IC583284 and IC583278 were found to possess high methyl eugenol content (> 70 %). Eugenol has been reported to be largely responsible for the therapeutic potentials of tulsi, while methyl eugenol is a high value aroma chemical used as flavouring agent. The results suggest holy basil have a potential as a new essential oil crops and can provide oil yields and composition typical for the respective species.