Quinoline and derivatives represent an important class of heterocyclic in the medicinal chemistry field because its wide range of biological activities, including antituberculosis . Machado and coworkers have reported a series of quinoline derivatives with inhibitory activity against a clinical isolate of an MDR-TB strain. Compound (19) (Figure 7) showed a potent MIC90 value of 0.05 μM and activity against macrophage intracellular mycobacteria. Moreover, the authors also performed metabolic stability and drug–drug interaction studies. Compound (19) exhibited moderate metabolic stability in the human S9 fraction, with an in vitro intrinsic clearance (Clint) of 14.3 mL/min/kg and T1/2 of 21.8 min. In addition, this derivative did not alter the enzymatic levels in the liver, suggesting a minimal risk of metabolic drug−drug interactions . Later, the same group has reported a novel series of quinoline derivatives with improved antituberculosis activity. Compound (20) (Figure 7) exhibited a potent MIC90 value of 1 nM against a clinical isolate of an MDR-TB strain with a Clint of 14.8 mL/min/kg and T1/2 of 19.4 min .