Design, synthesis and biological evaluation of novel oxindole analogs as antitubercular agents

To design, synthesize and evaluate oxindole derivatives for antitubercular activity. We synthesized the derivatives, confirmed their structures by H/ C NMR and mass spectrometry, and evaluated them for antitubercular activity against H37Rv strain using the microplate alamarBlue™ assay. Among all the synthesized derivatives, , and exhibited excellent antitubercular activity (minimum inhibitory concentration [MIC]: 0.78 μg/ml). Compounds with a MIC ≤1.56 were tested for cytotoxicity against human embryonic kidney cells and were found to be relatively nontoxic. Molecular docking analysis of , and was performed to determine their binding patterns at the active site of DNA topoisomerase II (PDB-5BS8). In drug combination studies, , and showed synergism with isoniazid. The obtained results reveal that oxindole derivatives exhibit potent antitubercular activity.