- Efficient analoging around ethionamide to explore thioamides bioactivation pathways triggered by boosters in Mycobacterium tuberculosis
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Ethionamide is a key antibiotic prodrug of the second-line chemotherapy regimen to treat tuberculosis. It targets the biosynthesis of mycolic acids thanks to a mycobacterial bioactivation carried out by the Baeyer-Villiger monooxygenase EthA, under the control of a transcriptional repressor called EthR. Recently, the drug-like molecule SMARt-420, which triggers a new transcriptional regulator called EthR2, allowed the derepression a cryptic alternative bioactivation pathway of ethionamide. In order to study the bioactivation of a collection of thioisonicotinamides through the two bioactivation pathways, we developed a new two-step chemical pathway that led to the efficient synthesis of eighteen ethionamide analogues. Measurements of the antimycobacterial activity of these derivatives, used alone and in combination with boosters BDM41906 or SMARt-420, suggest that the two different bioactivation pathways proceed via the same mechanism, which implies the formation of similar metabolites. In addition, an electrochemical study of the aliphatic thioisonicotinamide analogues was undertaken to see whether their oxidation potential correlates with their antitubercular activity measured in the presence or in the absence of the two boosters.
- Prieri, Marion,Frita, Rosangela,Probst, Nicolas,Sournia-Saquet, Alix,Bourotte, Marilyne,Déprez, Benoit,Baulard, Alain R.,Willand, Nicolas
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- Diarylthiazole: An antimycobacterial scaffold potentially targeting PrrB-PrrA two-component system
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Diarylthiazole (DAT), a hit from diversity screening, was found to have potent antimycobacterial activity against Mycobacterium tuberculosis (Mtb). In a systematic medicinal chemistry exploration, we demonstrated chemical opportunities to optimize the potency and physicochemical properties. The effort led to more than 10 compounds with submicromolar MICs and desirable physicochemical properties. The potent antimycobacterial activity, in conjunction with low molecular weight, made the series an attractive lead (antibacterial ligand efficiency (ALE) >0.4). The series exhibited excellent bactericidal activity and was active against drug-sensitive and resistant Mtb. Mutational analysis showed that mutations in prrB impart resistance to DAT compounds but not to reference drugs tested. The sensor kinase PrrB belongs to the PrrBA two component system and is potentially the target for DAT. PrrBA is a conserved, essential regulatory mechanism in Mtb and has been shown to have a role in virulence and metabolic adaptation to stress. Hence, DATs provide an opportunity to understand a completely new target system for antimycobacterial drug discovery.
- Bellale, Eknath,Naik, Maruti,Vb, Varun,Ambady, Anisha,Narayan, Ashwini,Ravishankar, Sudha,Ramachandran, Vasanthi,Kaur, Parvinder,McLaughlin, Robert,Whiteaker, James,Morayya, Sapna,Guptha, Supreeth,Sharma, Sreevalli,Raichurkar, Anandkumar,Awasthy, Disha,Achar, Vijayshree,Vachaspati, Prakash,Bandodkar, Balachandra,Panda, Manoranjan,Chatterji, Monalisa
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supporting information
p. 6572 - 6582
(2014/10/15)
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