Regio Selective Synthesis of Pyrazole Derivatives of 5‐Chloro‐2‐Methoxy Phenyl Hydrazide and Their Biological Evaluation

ABSTRACT Present study involves synthesis of derivatives of (5‐chloro‐2‐methoxyphenyl) (5‐alkyl‐3‐(substituted) (phenyl/alkyl)‐1 H ‐pyrazol‐1‐yl) methanones. Structural elucidation of the synthesized compounds was depicted by the data of 1 H and 13 C NMR, IR, and Mass spectral analysis. The newly synthesized compounds 1a–1d and 2a–2i were screened in vitro against Mycobacterium tuberculosis H37Ra using an established XRMA protocol. Among the screened compounds, 2d, 2f, and 2h showed good percent inhibition against the active stage of M. tuberculosis H37Ra 80.77, 55.70, and 79.54, respectively, at 30 μg/mL of inhibitor concentration. Further in secondary screening, compound 2d exhibited significant antitubercular activity on the active stage of M. tuberculosis H37Ra with IC 50 of 0.208 μg/mL. The synthesized compounds were also screened for antibacterial activity and found no significant activity against Gram‐positive Bacteria Bacillus subtitles and Staphylococcus aureus and Gram negative bacteria Pseudomonas aeruginosa and Escherichia coli at 30 μg/mL, which confirms the specificity of inhibitory activity against M. tuberculosis and more selectively against the active stage. The present study will be helpful for the further development of these molecules into antitubercular lead candidates.