ABSTRACT
Isoniazid (INH) remains one of the cornerstones of antitubercular chemotherapy for drug-sensitive strains of M. tuberculosis bacteria. However, the increasing prevalence of multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains containing mutations in the KatG enzyme, which is responsible for the activation of INH into its antitubercular form, have rendered this drug of little or no use in many cases of drug-resistant tuberculosis. Presented herein is a novel family of antitubercular direct NADH-dependent 2-trans enoyl-acyl carrier protein reductase (InhA) inhibitors based on an N-benzyl-4-((heteroaryl)methyl)benzamide template; unlike INH, these do not require prior activation by KatG. Given their direct InhA target engagement, these compounds should be able to circumvent KatG-related resistance in the clinic. The lead molecules were shown to be potent inhibitors of InhA and showed activity against M. tuberculosis bacteria. This new family of inhibitors was found to be chemically tractable, as exemplified by the facile synthesis of analogues and the establishment of structure-activity relationships. Furthermore, a co-crystal structure of the initial hit with the enzyme is disclosed, providing valuable information toward the design of new InhA inhibitors for the treatment of MDR/XDR tuberculosis.
Subject(s)
Antitubercular Agents/pharmacology , Benzamides/pharmacology , Enzyme Inhibitors/pharmacology , Inhibins/antagonists & inhibitors , Mycobacterium tuberculosis/drug effects , NAD/metabolism , Tuberculosis, Multidrug-Resistant/drug therapy , Animals , Antitubercular Agents/chemical synthesis , Antitubercular Agents/chemistry , Benzamides/chemical synthesis , Benzamides/chemistry , Dose-Response Relationship, Drug , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/chemistry , Female , Inhibins/metabolism , Mice , Mice, Inbred C57BL , Microbial Sensitivity Tests , Molecular Structure , Mycobacterium tuberculosis/enzymology , Structure-Activity Relationship , Tuberculosis, Multidrug-Resistant/enzymologyABSTRACT
One way to speed up the TB drug discovery process is to search for antitubercular activity among compound series that already possess some of the key properties needed in anti-infective drug discovery, such as whole-cell activity and oral absorption. Here, we present MGIs, a new series of Mycobacterium tuberculosis gyrase inhibitors, which stem from the long-term efforts GSK has dedicated to the discovery and development of novel bacterial topoisomerase inhibitors (NBTIs). The compounds identified were found to be devoid of fluoroquinolone (FQ) cross-resistance and seem to operate through a mechanism similar to that of the previously described NBTI GSK antibacterial drug candidate. The remarkable in vitro and in vivo antitubercular profiles showed by the hits has prompted us to further advance the MGI project to full lead optimization.
Subject(s)
Antitubercular Agents/pharmacology , Enzyme Inhibitors/pharmacology , Mycobacterium tuberculosis/drug effects , Mycobacterium tuberculosis/enzymology , Animals , Drug Discovery , Female , Fluoroquinolones/pharmacology , Mice , Mice, Inbred C57BL , Microbial Sensitivity Tests , Models, Molecular , Mycobacterium bovis/drug effects , Topoisomerase I Inhibitors/pharmacology , Tuberculosis/drug therapy , Tuberculosis/microbiologyABSTRACT
With the aim of fuelling open-source, translational, early-stage drug discovery activities, the results of the recently completed antimycobacterial phenotypic screening campaign against Mycobacterium bovis BCG with hit confirmation in M. tuberculosis H37Rv were made publicly accessible. A set of 177 potent non-cytotoxic H37Rv hits was identified and will be made available to maximize the potential impact of the compounds toward a chemical genetics/proteomics exercise, while at the same time providing a plethora of potential starting points for new synthetic lead-generation activities. Two additional drug-discovery-relevant datasets are included: a) a drug-like property analysis reflecting the latest lead-like guidelines and b) an early lead-generation package of the most promising hits within the clusters identified.
