Synthesis, characterization and evaluation of in vitro antimicrobial activity of carbonyl derivatives of sulphonamide compounds

Sulphonamide compounds (1-4) were synthesized by simple condensation of sulphanilamide with carbonyl derivatives. The compounds were characterized by elemental analysis, IR, H-1 and C-13 NMR spectroscopy. All the carbonyl derivatives form Schiff base compounds (2-4) with sulphanilamide while with acetylacetone; the Schiff base compound formed undergoes keto-enol tautomer and then crystallized as 4-(4-oxopent-2-en-2-ylamino)benzene sulfonamide compound (1) in which azomethine nitrogen atom is protonated. The H-1 and C-13 NMR spectroscopy data indicates the formation of the compounds and reveals the protonation of azomethine nitrogen atom in compound 1 which has also been confirmed by X-ray crystal structure. All the compounds were screened for antibacterial and antifungal activities against different microbes. Compound 1 and 2 were found to be effective antifungal agents against C. albicans while 3 and 4 shown antibacterial activities against Escherichia coli and Salmonella paratyphi. The minimum inhibition concentration of all the compounds were also determined and compared with standard drugs.