Identification and optimization of pyridine carboxamide-based scaffold as a drug lead for Mycobacterium tuberculosis

Abstract

New drugs with novel mechanisms of action are urgently needed to tackle the issue of drug-resistant tuberculosis. Here, we have performed phenotypic screening using the Pathogen Box library obtained from the Medicines for Malaria Venture against Mycobacterium tuberculosis in vitro . We have identified a pyridine carboxamide derivative, MMV687254, as a promising hit. This molecule is specifically active against M. tuberculosis and Mycobacterium bovis Bacillus Calmette-Guérin ( M. bovis BCG) but inactive against Enterococcus faecalis , Staphylococcus aureus , Klebsiella pneumoniae , Acinetobacter baumanii , Pseudomonas aeruginosa , and Escherichia coli pathogens. We demonstrate that MMV687254 inhibits M. tuberculosis growth in liquid cultures in a bacteriostatic manner. Surprisingly, MMV687254 was as active as isoniazid in macrophages and inhibited M. tuberculosis growth in a bactericidal manner. Mechanistic studies revealed that MMV687254 is a prodrug and that its anti-mycobacterial activity requires AmiC - dependent hydrolysis. We further demonstrate that MMV687254 inhibits M. tuberculosis growth in macrophages by inducing autophagy. In the present study, we have also carried out a detailed structure-activity relationship study and identified a promising novel lead candidate. The identified novel series of compounds also showed activity against drug-resistant M. bovis BCG and M. tuberculosis clinical strains. Finally, we demonstrate that in contrast to MMV687254, the lead molecule was able to inhibit M. tuberculosis growth in a chronic mouse model of infection. Taken together, we have identified a novel lead molecule with a dual mechanism of action that can be further optimized to design more potent anti-tubercular agents.

α-Aminooxyacetic acid derivatives acting as pro-drugs againstMycobacterium tuberculosis

“…17 Furthermore, MMV687254, a pyridine carboxamide derivative, also requires AmiC-dependent hydrolysis for antibacterial activity against M. tuberculosis , although the antimycobacterial mechanism following hydrolysis remained unknown. 18 Therefore, we hypothesized that the KSKs are pro-drugs that are hydrolyzed by intracellular amidohydrolases, Rv0552 or AmiC, to bioactive metabolites.…”

“…AmiC has recently been discovered to mediate the activation of two other classes of amide-containing pro-drug compounds, indole-4-carboxamides and pyridine carboxamides. 17,18 However, for these compounds, monoactivation only by AmiC occurs, while the studied α-aminooxyacetic acid derivatives differ by involving alternative activation by AmiC and Rv0552. To our knowledge, Rv0552 has not previously been reported to be involved in activation of, or resistance to, antimycobacterial compounds.…”