Evaluation of terpene-rich extract of Lantana camara L. leaves for antimicrobial activity against mycobacteria using Resazurin Microtiter Assay (REMA)

Abstract

Background: Lantana camara L. (Verbenaceae) is notorious weed, leaves of which are rich in terpenes, in the form of essential oil. Terpenes have potent antimicrobial and antimycobacterial activities. Depending upon saponification characteristic of lipids and waxes; unsaponified petroleum ether extract which contain only terpenes, can be prepared. Terpene-rich extract (TRE) of L. camara L. leaves has exhibited higher antioxidant and antimicrobial activities as compared to any solvent extract. Aim: Present attempt was aimed towards preparation of terpene-rich extract (TRE) of L. camara L. leaves; its phytochemical analysis by NMR and evaluation of its anti-mycobacterial activity. Methods: In order to retain only terpenes in extract, in present study, petroleum ether extract of L. camara L. leaves was saponified using aqueous potassium hydroxide and remaining unsaponified extract (TRE) was phytochemically analyzed using chromatographic and NMR techniques. Further, TRE was screened for its anti-mycobacterial potential against Mycobacterium tuberculosis (H37Ra) by Resazurin Microtiter Assay (REMA) method. Results: Detail phytochemical analysis reflected successful preparation of extract rich in terpenes. H1-NMR analysis proved the presence of various terpenes and triterpenoids, reported earlier for their presence in the plant. TRE was then found to have significant anti-mycobacterial activity with MIC90 value up to 50 µg/ml. Conclusion: TRE contains different terpenes in specific proportion which makes it significantly potent antimycobacterial with minimum MIC90 value up to 50 µg/ml. REMA found to be economic and easier as compared to other techniques. Keywords: Lantana camara L., Terpene-rich extract, REMA, Antimycobacterial