Expanding Benzoxazole-Based Inosine 5′-Monophosphate Dehydrogenase (IMPDH) Inhibitor Structure–Activity As Potential Antituberculosis Agents

• Published in: Journal of medicinal chemistry Vol. 61; no. 11; pp. 4739 - 4756
• Main Authors: Chacko, Shibin, Boshoff, Helena I. M, Singh, Vinayak, Ferraris, Davide M, Gollapalli, Deviprasad R, Zhang, Minjia, Lawson, Ann P, Pepi, Michael J, Joachimiak, Andrzej, Rizzi, Menico, Mizrahi, Valerie, Cuny, Gregory D, Hedstrom, Lizbeth
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 14.06.2018; Amer Chemical Soc; American Chemical Society (ACS)
• Subjects: BASIC BIOLOGICAL SCIENCES; Chemistry, Medicinal; Life Sciences & Biomedicine; Pharmacology & Pharmacy; Science & Technology; MYCOBACTERIUM-TUBERCULOSIS; IN-VITRO; MECHANISM; MONOPHOSPHATE DEHYDROGENASE; 5'-MONOPHOSPHATE DEHYDROGENASE; CRYPTOSPORIDIUM-PARVUM; COMPLEXES; BATEMAN DOMAIN; SELECTIVITY; DISCOVERY
• ISSN: 0022-2623; 1520-4804
• DOI: 10.1021/acs.jmedchem.7b01839

New drugs and molecular targets are urgently needed to address the emergence and spread of drug-resistant tuberculosis. Mycobacterium tuberculosis (Mtb) inosine 5′-monophosphate dehydrogenase 2 (MtbIMPDH2) is a promising yet controversial potential target. The inhibition of MtbIMPDH2 blocks the biosynthesis of guanine nucleotides, but high concentrations of guanine can potentially rescue the bacteria. Herein we describe an expansion of the structure–activity relationship (SAR) for the benzoxazole series of MtbIMPDH2 inhibitors and demonstrate that minimum inhibitory concentrations (MIC) of ≤1 μM can be achieved. The antibacterial activity of the most promising compound, 17b (Q151), is derived from the inhibition of MtbIMPDH2 as demonstrated by conditional knockdown and resistant strains. Importantly, guanine does not change the MIC of 17b, alleviating the concern that guanine salvage can protect Mtb in vivo. These findings suggest that MtbIMPDH2 is a vulnerable target for tuberculosis.