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Amid the global health crisis instigated by COVID-19, the resurgence of tuberculosis (TB) has underscored the urgent need for innovative solutions. With TB claiming 1.6 million lives in 2021, it remains a formidable challenge, particularly in underdeveloped regions. Central to Mycobacterium tuberculosis (Mtb) pathogenesis is the decaprenylphosphoryl-β-D-ribose oxidase (DprE1)/decaprenylphosphoryl-2-keto-β-D-erythropentose reductase (DprE2) complex, pivotal for synthesizing decaprenylphosphoryl-arabinofuranose (DPA), a critical component of mycobacterial cell walls. DprE1 has emerged as a prime therapeutic target, with several inhibitors in clinical trials. This review elucidates the indispensability of DprE1, examines existing ligands, and delineates key considerations for the development of next-generation anti-TB therapeutics. Our analysis highlights the potential of DprE1 inhibitors to revolutionize TB treatment, emphasizing the need for continued research and development in this area to address the evolving landscape of TB and drug resistance.

Tuberculosis (TB) is a disease that plagues the frailest members of society. We have developed a family of N-alkyl nitrobenzamides that exhibit promising antitubercular activities and can be considered a structural simplification of known inhibitors of decaprenylphosphoryl-β-D-ribofuranose 2′-oxidase (DprE1), an essential Mycobacterium tuberculosis (Mtb) enzyme and an emergent antitubercular target. Hereby, we report the development of these compounds via a simple synthetic methodology as well as their stability, cytotoxicity, and antitubercular activity. Studying their in vitro activity revealed that the 3,5-dinitro and the 3-nitro-5-trifluoromethyl derivatives were the most active, and within these, the derivatives with intermediate lipophilicities presented the best activities (MIC of 16 ng/mL). Additionally, in an ex vivo macrophage model of infection, the derivatives with chain lengths of six and twelve carbon atoms presented the best results, exhibiting activity profiles comparable to isoniazid. Although the proof is not definite, the assessment of susceptibility over multiple mycobacterial species, together with the structure similarities with known inhibitors of this enzyme, support DprE1 as a likely target of action for the compounds. This idea is also reinforced by the docking studies, where the fit of our more active compounds to the DprE1 binding pocket is very similar to what was observed for known inhibitors like DNB1.

Tuberculosis (TB) continues to be a major global health challenge and a leading cause of death from infectious diseases. Inspired by the results from a previous work by our group on antimycobacterial N-alkylnitrobenzamides, which are structurally related to the nitrobenzamide family of decaprenylphosphoryl-β-d-ribose oxidase (DprE1) inhibitors, the present study explored a broad array of substituted benzamides. We particularly focused on previously unexplored 3,5-dinitrobenzamide derivatives. Starting with 3,5-dinitrobenzoic acid, we synthesized a diverse library of amides, incorporating both linear and cyclic amine moieties and also assessed the impact of terminal aromatic groups connected through ether, ester, or amide bonds on the bioactivity of the compounds. The synthesis primarily utilized nucleophilic addition/elimination, SN2, and Mitsunobu reactions. The activity was impacted mainly by two structural features, the addition of an aromatic moiety as a terminal group and the type of linker. The most interesting compounds (c2, d1, and d2, MIC = 0.031 μg/mL) exhibited activities against Mycobacterium Tuberculosis (Mtb) H37Rv comparable to isoniazid. Complementary computational studies helped elucidate potential interactions with DprE1, enhancing our understanding of the molecular basis of their action. Our findings suggest that the most active compounds provide a promising foundation for the continued development of new antimycobacterial agents.

Decaprenylphosphoryl-β-d-ribose oxidase (DprE1) is the flavoprotein subunit of decaprenylphosphoryl-d-ribose epimerase involved in cell wall synthesis in Mycobacterium tuberculosis and catalyzes the conversion of decaprenylphosphoryl ribose to decaprenylphosphoryl arabinose. DprE1 is a potential target against tuberculosis, including multidrug-resistant tuberculosis. We identified potential DprE1 inhibitors from the ChemDiv dataset through virtual screening based on pharmacophore and molecular docking. Thirty selected compounds were subjected to absorption, distribution, metabolism, excretion, and toxicity prediction with the Discovery Studio software package. Two compounds were obtained as hits for inhibiting DprE1 activity in M. tuberculosis and are suitable for further in vitro and in vivo evaluation.

Pyrazinamide, the first-line antitubercular drug, has been regarded the basic component of tuberculosis treatment for over sixty years. Researchers have investigated its effect on Mycobacterium tuberculosis for this long time, and as a result, new potential targets of pyrazinamide or its active form, pyrazinoic acid, have been found. We have designed and prepared 3-(phenyl-carbamoyl)pyrazine-2-carboxylic acids as more lipophilic derivatives of pyrazinoic acid. We also prepared methyl and propyl derivatives as prodrugs with further increased lipophilicity. Antimycobacterial, antibacterial and antifungal growth inhibiting activity was investigated in all prepared compounds. 3-[(4-Nitrophenyl)carbamoyl]pyrazine-2-carboxylic acid (16) exerted high antimycobacterial activity against Mycobacterium tuberculosis H37Rv with MIC = 1.56 μg·mL−1 (5 μM). Propyl 3-{[4-(trifluoromethyl)phenyl]carbamoyl}pyrazine-2-carboxylate (18a) showed also high antimycobacterial activity against Mycobacterium tuberculosis H37Rv with MIC = 3.13 μg·mL−1. In vitro cytotoxicity of the active compounds was investigated and no significant cytotoxic effect was observed. Based to structural similarity to known inhibitors of decaprenylphosphoryl-β-d-ribose oxidase, DprE1, we performed molecular docking of the prepared acids to DprE1. These in silico experiments indicate that modification of the linker connecting aromatic parts of molecule does not have any negative influence on the binding.