Synthesis and Antimicrobial Screening of Some Novel Cinnoline Derivatives

Cinnoline is a nitrogenous organic base obtained from certain complex diazo compounds. It is an isosteric, relative to either quinoline or iso quinoline. Cinnoline itself is toxic and shows antibacterial activity against Escherichia coli. None of its derivatives have been found in nature. Its condensed bicyclic aromatic heterocycle contains two nitrogen atoms. Sulphamido group is introduced into cinnoline nucleus to get compounds with enhanced potency. Pyrazolocinnolines are obtained by diazotization of sulphanilamide followed by coupling to form corresponding hydrazones which, on intramolecular cyclisation forms 3-acetyl-6-sulphamido-cinnolin-4-ones [CN-I]. Further, treatment with hydrazine hydrate yields the expected 3’-methyl-6-sulphamido-1’substituted-pyrazolo [4, 3-C] cinnoline derivatives. The compounds were characterized by analytical techniques like TLC, UV, IR, NMR Spectral studies. Screening for antimicrobial activity against bacterial organisms like Escherichia coli, Klebsiella aurogeniosea, Micrococcus luteus, Bacillus cereus and fungal organism like Candida albicans using Disc Diffusion Method were performed.