Synthesis and Evaluation of New 5-methylisoxazole-3-carboxamide Derivatives as Antitubercular Agents

Background: Tuberculosis is responsible for the world’s leading cause of death affecting one third of the world’s population by the latent or dormant form despite the current chemotherapy. For the effective management of MDR or XDR-TB, new lead compounds or novel therapeutic targets are urgently needed. The present investigation is aimed at creating a new and hitherto unreported molecular framework encompassing isoxazole moiety with carboxamide derivatives for the antitubercular activity. Methods: 5-methylisoxazole-3-carboxamide derivatives (4-20) were synthesized in good yield and were characterised by, spectral studies. In vitro antitubercular activity of the synthesized compounds was determined against Mycobacterium tuberculosis H37Rv by MABA method and in vitro antibacterial activity against Bacillus subtilis and Escherichia coli by serial dilution method. Results: The titled compounds, 10 and 14 showed significant antitubercular activity with MIC of 3.125 μM and 9 and 13 with MIC of 6.25 μM among the tested compounds. The active compounds have shown good safety profile against Vero and HepG2 Cell lines. The compounds 9, 13, 19 and 20 showed significant antibacterial activity with MIC of 6.25 μM and 15 and 17 showed activity with MIC of 12.5 μM among the tested compounds. Conclusion: In conclusion, we reported the convenient synthetic method for the 5-methylisoxazole-3-carboxamides. The results of antitubercular activity were encouraging. With structure base drug design approach and suitable molecular modifications of the synthesized compounds 9, 10, 13 and 14, it is possible to develop lead molecule with better antitubercular potential.