Hybrid molecules between benzenesulfonamides and active antimicrobial benzo[d]isothiazol-3-ones.

Novel hybrid molecules between benzenesulfonamides and active antimicrobial 2-amino-benzo[d]isothiazol- 3-ones were synthesized and characterised and their in vitro antimicrobial activity was evaluated by the minimal inhibitory concentration (MIC). The compounds exhibit moderate antibacterial properties against Gram-positive bacteria (MIC 6–100 microg ml-1) such as several bacilli, staphylococci and streptococci, including methicillin-resistant Staphylococcus aureus and Staphylococcus epidermidis strains, while no inhibition of Gram-negative Escherichia coli is detected up to the concentration of 100 microg ml-1. Synergistic inhibitory activity occurs when sulfanilamides 4a and 4c are tested in combination with trimethoprim against S. aureus. Concerning antifungal properties, only compound 4c is able to inhibit the growth of Saccharomyces cerevisiae and Cryptococcus neoformans yeasts and several dermatophytes. Structure–activity relationships are discussed.