Biological Evaluation of Esters of 4-Carboxylate-1,2,3-triazine and Analogs as New Potential Anti-Mycobacterium tuberculosis Agents.

In searching for novel molecules to act as antibacterial agents, particularly against Mycobacterium tuberculosis bacteria, three series of C5- and C6-substituted 1,2,3-triazine compounds were investigated: 1,2,3-triazine-4-carboxylate 1-oxide (series 1), 1,2,3-triazine-4-carboxylate (series 2), and 3,6-dihydro-1,2,3-triazine-4-carboxylate 1-oxide derivatives (series 3). Their structural elucidation was confirmed by 1H-NMR, 13C-NMR, and HRMS. We determined their antibacterial activity (MIC value) using the MABA against the M. tuberculosis H37Rv strain, as well as their physicochemical and pharmacokinetic properties. Finally, to determine their potential mode of action, an inhibition assay against M. tuberculosis DNA gyrase was performed. Compounds 4-ethoxycarbonyl-5-(3-methoxyphenyl)-1,2,3-triazine (2l) and 4-ethoxycarbonyl-5 -(n-propyl)-1,2,3-triazine (3s) exhibited high activity against M. tuberculosis with MIC values < 5.90 µg/mL and selectivity index of 18.56 and 8.36, respectively. Additionally, compound 2m also exhibited anti-mycobacterial activity with MIC values < 10.0 µg/mL. However, none of the selected compounds inhibited the activity of M. tuberculosis DNA gyrase, suggesting that another drug target may be involved as a mode of action. These results encourage exploring the use of 1,2,3-triazine as a scaffold for the development of new anti-mycobacterium agents.