Pyrrolo[3,4-c]pyridine-1,3(2H)-diones: A Novel Antimycobacterial Class Targeting Mycobacterial Respiration.
van der Westhuyzen R, Winks S, Wilson CR, Boyle GA, Gessner RK, Soares de Melo C, Taylor D, de Kock C, Njoroge M, Brunschwig C, Lawrence N, Rao SP, Sirgel F, van Helden P, Seldon R, Moosa A, Warner DF, Arista L, Manjunatha UH, Smith PW, Street LJ, Chibale K.
High-throughput screening of a library of small polar molecules against Mycobacterium tuberculosis led to the identification of a phthalimide-containing ester hit compound (1), which was optimized for metabolic stability by replacing the ester moiety with a methyl oxadiazole bioisostere. A route utilizing polymer-supported reagents was designed and executed to explore structure-activity relationships with respect to the N-benzyl substituent, leading to compounds with nanomolar activity. The frontrunner compound (5h) from these studies was well tolerated in mice. A M. tuberculosis cytochrome bd oxidase deletion mutant (ΔcydKO) was hyper-susceptible to compounds from this series, and a strain carrying a single point mutation in qcrB, the gene encoding a subunit of the menaquinol cytochrome c oxidoreductase, was resistant to compounds in this series. In combination, these observations indicate that this novel class of antimycobacterial compounds inhibits the cytochrome bc1 complex, a validated drug target in M. tuberculosis.