Intramacrophage potential of a tetrahydropyridine: A promising compound in combating Mycobacterium tuberculosis.

Due to several obstacles in treating tuberculosis (TB), the search for new therapeutic alternatives remains a global priority. The nitrogenous heterocyclic compounds are promising in searching for new anti-Mycobacterium tuberculosis molecules, and our previous results highlight the potential of tetrahydropyridines. After exploring the antimycobacterial potential and putative mechanism of action of a tetrahydropyridine derivative (NUNL02), we seek to measure the oxidative stress caused by NUNL02 inside the extracellular replicating M. tuberculosis since it could be the reason for the NUNL02 bactericidal effect against replicating and starved M. tuberculosis; and to evaluate the anti-M. tuberculosis activity of NUNL02 against the intracellular bacillus (even combined with an anti-TB drug) to explore the potential of this tetrahydropyridine as a promising adjuvant for TB therapy. Briefly, we assessed the activity of NUNL02 against the H37Rv strain and evaluated the combination of NUNL02 and rifampicin (RIF), at previously defined subinhibitory concentrations, against intramacrophage M. tuberculosis. NUNL02, in addition to promote the oxidative stress inside the extracellular replicating M. tuberculosis as a possible indirect mechanism of action, also presented bactericidal potential as promising as RIF against intracellular bacilli. Thus, our findings reinforce NUNL02 as a promising scaffold for the development of new options for TB.

2,2,2-trifluoro-1-(1,4,5,6-tetrahydropyridin-3-yl)ethanone derivative as efflux pump inhibitor in Mycobacterium tuberculosis.

Although the administration of combined therapy is efficient to tuberculosis (TB) treatment caused by susceptible Mycobacterium tuberculosis strains, to overcome the multidrug resistance is still a challenge. Some studies have reported evidence about tetrahydropyridines as a putative efflux pump inhibitor, including in mycobacteria, being a promising strategy against M. tuberculosis. Thus, we investigated the biological potential of 2,2,2-trifluoro-1-(1,4,5,6-tetrahydropyridin-3-yl)ethanone derivative (NUNL02) against two strains of M. tuberculosis. NUNL02 was able to increase the susceptibility of the multidrug resistant strain to the anti-TB drugs, resulting in synergism with rifampicin. Still, we assume that this compound plays a role in the efflux mechanism in M. tuberculosis, besides, to be able to kill the bacillus under the deprivation of essential nutrients. Thus, our findings highlight NUNL02 as a promising prototype to develop a new adjuvant for TB treatment, mainly as EPI.