Metabolomics using Gas chromatography-mass spectrometry and antibacterial activity of nine Ocimum taxa of Dakshin Dinajpur district, West Bengal, India

Abstract

Ocimum traditionally known as Holy Basil or Tulsi is an available herb plenty across the country. Traditionally, it is used against a number of human diseases. In this present study, the metabolites present in the ethanolic extracts of nine Ocimum taxa, O. tenuiflorum L. (Green and purple type) two morphotypes of O. basilicum L., (Babu and Marua tulsi) two morphotypes of O. gratissimum L. (Ram and Ajowan tulsi) and each one from O. americanum L. (Bon tulsi), O. × africanum Lour. (Lebu tulsi), and O. kilimandscharicum Guerke.grown naturally in Dakshin Dinajpur district, West Bengal, India were identified using Gas chromatography–mass spectrometry (GC-MS). Among the identified metabolites, carbohydrates, aliphatic alcohols, aliphatic acids, fused ring aromatic hydrocarbon, amino acids, phenolic compounds, quinone, steroids, terpenoids and vitamin E were the chief constituents. The occurrence of these metabolites describes the high biological activity of Ocimum species. Furthermore, in vitro antibacterial activities were also identified against four bacterial strains, Staphylococcus aureus (MTCC 96), Bacillus cereus (MTCC 1305), Proteus vulgaris (MTCC 1771) and Escherichia coli (MTCC 2939). Tested bacterial strains were taken from the Institute of Microbial Technology, Chandigarh, India The results indicated that the ethanolic extracts of all the nine Ocimum taxa have satisfactory minimum inhibitory concentration (MIC) values against the tested microorganisms. O. tenuiflorum has the highest (91.03 %) metabolic content whereas O. × africanum has the minimum. This would definitely serve as a scientific basis of the traditional use of basil against human ailments.