Inhibition of mycobacterial growth by plumbagin derivatives.

Electron transport and respiratory pathways are active in both latent and rapidly growing mycobacteria and remain conserved in all mycobacterial species. In mycobacteria, menaquinone is the sole electron carrier responsible for electron transport. Menaquinone biosynthesis pathway is found to be essential for the growth of mycobacteria. Structural analogs of the substrate or product of this pathway are found to be inhibitory for the growth of Mycobacterium smegmatis and M. tuberculosis. Several plumbagin [5-hydroxy-2-methyl-1, 4-naphthaquinone] derivatives have been analyzed for their inhibitory effects of which butyrate plumbagin was found to be most effective on M. smegmatis mc(2)155, whereas crotonate plumbagin showed greater activity on M. tuberculosis H37Rv. Effect on electron transport and respiration was demonstrated by butyrate plumbagin inhibiting oxygen consumption in M. smegmatis. Structural modifications of these molecules can further be improved upon to generate new molecules against mycobacteria.