Condensation of ketones 1a-b with deferent aldehydes 2a-e gives chalcones 3a-j. These chalcones on
cyclization with hydrazine hydrate/ phenylhydrazine in the presence of glacial acetic acid give the corresponding
pyrazolines 4a-t. The structures of new compounds have been established by extensive IR, NMR and X-ray crystallographic
studies and were assayed for their antitubercular activity against M. tuberculosis H37Rv and INH resistant M. tuberculosis
strains using agar dilution method. Among the both derivative compounds, 4-hydroxy-3-(5-(4-
trifluoromethyl)phenyl)-4,5-dihydro-1H-pyrazol-3-yl-2H-chromen-2-one 4m produced the highest efficacy, exhibited
>90% inhibition against MTB at a concentration of 4.94 µM and against INHR-MTB at 14.78 µM.
Keywords: Mycobacterium tuberculosis, 3-Acetyl-4-hydroxycoumarins, Chalcones and Pyrazolines.
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