Synthesis, Characterization and Evaluation of Biological Properties of Pyrazolo- and Oxazolo-pyridocarbazoles and Pyridoazacarbazoles as Potent Anti-microbial Agents

Aims: Fused carbazoles, azacarbazoles and quinolines are endowed with a wide array of pharmacological properties. Keeping these properties in the mind, the study was undertaken to seek structural modifications to generate novel synthetic analogues of carbazoles, azacarbazoles and quinolines and to examine their biological properties.

Methodology: Pyrazole and isoxazole condensed pyridocarbazoles and pyridoazacarbazoles were synthesized by the cyclo-condensation reactions of corresponding enol ethers, chalcones, oxoketenedithio acetals and dimethyl aminomethylene ketones with hydroxylamine hydrochloride and hydrazine hydrate respectively.

Results: Pyrazoles and isoxazoles were synthesized. The structures of all the compounds have been established on the basis of their elemental analysis and spectral (IR, 1H NMR and MS) data. Formation of the compounds were also confirmed by the spectral data.

Conclusion: Compound 8-methyl-4,5-dihydroisoxazolo[4,3-i]pyrido[2,3-a]carbazol-10-ol (12b) and 5-N-benzyl-8-methyl-3-methylthio-4H-pyrrazolo[4,3-i]pyrido[2,3-a]azacarbazol-10-ol (14a) were screened for the anti-bacterial (against E. coli and B. cereus) and anti-fungal (against M. phaseolina and F. solani) activities. Both the compounds showed moderate activities as compared to standards (Ciprofloxacin for anti-bacterial and Fluconazole for anti-fungal activity) used.