Looking for new targets: simple coumarins as antibacterial agents.

The dramatic worldwide increase of dangerous infections by resistant and multi-resistant microbes makes the search of new molecules and new chemical entities an important topic in Medicinal Chemistry. As the ideal drug candidate has not been attained, an intensive search for new and innovative antimicrobials is still needed. A small series of 3-amino/nitrocoumarins without substitutions or substituted by methyl or methoxy groups at different positions were synthesized and evaluated for their antibacterial and antifungal activities against clinical isolates of Staphylococcus aureus, Escherichia coli and Candida albicans strains. Some of these structurally simple molecules exhibited antibacterial activity. The preliminary SAR study showed that the antibacterial activity against E. coli and S. aureus was dependent on the kind and position of the substitution pattern at the coumarin moiety.