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

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 . We have identified a pyridine carboxamide derivative, MMV687254, as a promising hit. This molecule is specifically active against and Bacillus Calmette-Guérin ( BCG) but inactive against , , , , , and pathogens. We demonstrate that MMV687254 inhibits growth in liquid cultures in a bacteriostatic manner. Surprisingly, MMV687254 was as active as isoniazid in macrophages and inhibited growth in a bactericidal manner. Mechanistic studies revealed that MMV687254 is a prodrug and that its anti-mycobacterial activity requires AmiCdependent hydrolysis. We further demonstrate that MMV687254 inhibits 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 BCG and clinical strains. Finally, we demonstrate that in contrast to MMV687254, the lead molecule was able to inhibit 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.