Antimycobacterial activity of plant compounds against extensively drug resistant (XDR-TB) Mycobacterium tuberculosis

Abstract

Emergence of multidrug resistant strains of Mycobacterium tuberculosis is globally threatening the world and creating problems for the management of tuberculosis (TB). Traditional medicine and plant secondary metabolites are playing an important role in medicine; they are also useful for developing drugs for the treatment of tuberculosis. The present study was carried out to evaluate in vitro anti-tubercular activity of nine isolated plant compounds (Costunolide, Eremanthine, Chrysophanol, Friedeline, Plumbagin, Lupeol, Bergenin, karanjin and Flindersine) against M. tuberculosis H37Rv and M. tuberculosis XDR-1 (extensively drug resistant). The antimycobacterial activity of the nine natural compounds was evaluated by broth dilution method against H37Rv and XDR-1strains of M. tuberculosis. The concentrations employed were in the range of 0.5––64.0 µg/ml. Rifampicin was used as the standard control. MIC values of all the compounds were evaluated by using dose response curve. The results showed that out of the nine compounds tested Eremanthine, chrysophanol and karanjin showed the lowest MIC value of 08 µg/ml while Costunolide, Friedeline and plumbagin showed MIC value of 16 µg/ml against H37Rv strain. Lupeol showed MIC value of 32.0 µg/ml while Bergenin and flindersine showed MIC value of > 64.0 µg/ml. However, the tested compounds showed lesser activity against XDR-1 strain; the MIC values were in the range of 16.0 to 32.0 µg/ml. In this communication, the anti-TB activity of nine natural compounds have been reported against standard H37Rv strain and XDR-1 strain. The tested compounds showed appreciable activity against the standard H37Rv strain (MIC, 8.0 to 32.0 µg/ml). The compounds showed lesser activity towards the XDR-1 strain. Further work may be carried out on derivatives of these compounds which may lead to more potent compounds with lower toxicity.

Keywords

• Mycobacterium tuberculosis
• Plant compounds
• MIC
• Costunolide
• Eremanthin
• Chrysophanol