Chibale and coworkers have identified the compound pyrrolo[3,4-c]pyridine-1,3(2H)-dione (27) (Figure 10) through a phenotypic screening with potent antituberculosis activity; however, this compound presented drawbacks regarding its metabolic stability. The optimization of this molecule leads to compound (28) (Figure 10), which demonstrated MIC90 values below 0.6 μM against several clinical isolates and good metabolic stability in liver microsomes. The mycobacterial respiratory cytochrome bc1 complex was identified as the target for these compounds. Nevertheless, mouse pharmacokinetics studies showed high clearance and low plasma exposure for compound (28) . In another study, a series of twenty-seven benzo[d]oxazol-2(3H)-one derivatives were synthesized. Specifically, compound (29) (Figure 10) exhibited a promising antituberculosis activity against an XDR-TB clinical isolate, with MIC90 of 11.47 μM. The authors also demonstrated that compound (29) acts through the inhibition of the mycobacterial 2-trans-enoyl-acyl carrier protein reductase (InhA), a key enzyme involved in the mycolic acid biosynthesis in Mtb . Shuyi Si and coworkers have discovered several disubstituted oxazole analogues as potent antituberculosis agents. Among the twenty-five compounds evaluated, compound (30) (Figure 10) showed promising activity with MIC90 values of 2.2 and 4.3 μM against XDR-TB and MDR-TB, respectively. Moreover, compound (30) proved to be selective for Mtb because no activity against other bacteria was observed .