Synthesis and anti-tubercular activity of 6-Substtitutedaryl-4-Arylidene-4,5-dihydropyridazin-3(2H)-one derivatives against Mycobacterium tuberculosis

Pyridazine plays a significant role in pharmaceuticals particularly in the field of medicinal chemistry. Several 4-substituted-benzylidene-6-substituted-phenyl-dihydro-pyridazin-3(2H)-one derivatives (3a-q) were synthesized and evaluated for their antimicrobial activities with an aim to obtain promising antitubercular agents. In the first step, 6-aryl-tetrahydro-pyridazin-3-ones (2) were prepared by reacting 4-aryl-4-oxobutanoic acids (1) with hydrazine hydrate. Then, aryl-aldehydes were reacted with compounds 2 to furnish pyridazinones (3a-q). Finally, the synthesized compounds were evaluated for their in vitro antitubercular activities against mycobacterium strains and compared to reference drugs streptomycin (MIC value of 6.25μg/mL) and pyrizinamide (MIC value of 3.125μg/mL). Compound 3m and 3n was found to have most significant action. Identity of these compounds was ascertained using IR, NMR and mass spectral data results. Pyridazinone nucleus can be exploited for development of various synthetic compounds and their substituted pyridazinone derivatives to improved pharmacological activities From the antitubercular data, it could be concluded that compound bearing electron withdrawing group appeared most active against bacteria, whereas compound bearing electron releasing group exhibited less potent activity.