Synthesis and anti-tubercular activity of novel pyrazol-5(H)-one derivatives

In the present investigation, a series of 1-isonicotinoyl-3-methyl-4-(2-(substituted-phenyl)hydrazono)-1H-pyrazol-5(H)-ones were synthesized by the reaction between isonicotinohydrazide with substituted ethylacetoacetate derivatives using acetic acid as solvent which yielded substituted pyrazol-5(H)-one derivatives. Newly synthesized compounds were tested for their in vitro anti-tubercular activity against Mycobacterium tuberculosis H37Rv using the BACTEC 460 radiometric system. Among the synthesized compounds, 4-(2-(2,6-dichlorophenyl)hydrazono)-1-isonicotinoyl-3-methyl-1H-pyrazol-5(4H)-one and 4-(2-(1-isonicotinoyl-3-methyl-5-oxo-1H-pyrazol-4(5H)-ylidene)hydrazinyl) benzene-sulfonamide were found to be more active agent against M. tuberculosis H37Rv with minimum inhibitory concentration of 0.0034, 0.0032 μM at actual MIC 1.66 and 1.64 μg/mL, respectively.