Synthesis of new pyrazole and pyrazolin-5-one bearing 2-(quinolin-8-yloxy) acetohydrazide analogs as potential antimicrobial agents

2-(quinolin-8-yloxy)acetohydrazide (3) was prepared using ethyl 2-(quinolin-8-yloxy)acetate (2) and hydrazine hydrate. The acetohydrazide (3) derivative was used as a precursor for the preparation of 1-(3,5-dimethyl-4- (substitutedphenyldiazenyl)-1H-pyrazol-1-yl)-2-(quinolin-8-yloxy)ethanone (8a-d) and 3-methyl-4-(2- substitutedphenyl hydrazono)-1-(2-(quinolin-8-yloxy)acetyl)-1H-pyrazol-5(4H)-one (9a-e). The newly synthesized pyrazoles and pyrazolin-5-ones have been characterized by elemental analysis, IR, 1H NMR, 13C NMR and mass spectral data. The newly synthesized compounds have been screened for their antimicrobial activity against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi and fungi Aspergillus niger, Ustilago maydis, as compared to the standard drugs Gentamicin and Nystatin for bacterial and fungal growth respectively, using the agar disc diffusion method. All the compounds showed significant activity against both the strains.

Author(s): GajulaBheemaraju, GadhamshettyManjunath, Mallela Maheshand Peddakotla V. Ramana

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