Bacterial DNA gyrase and topoisomerase IV control the topological state of DNA during replication and are validated targets for antibacterial drug discovery. Starting from our recently reported 4,5,6,7-tetrahydrobenzo[1,2-d]thiazole-based DNA gyrase B inhibitors, we replaced their central core with benzothiazole-2,6-diamine scaffold and interchanged substituents in positions 2 and 6. This resulted in equipotent nanomolar inhibitors of DNA gyrase from Escherichia coli displaying improved inhibition of Staphylococcus aureus DNA gyrase and topoisomerase IV from both bacteria. Compound 27 was the most balanced inhibitor of DNA gyrase and topoisomerase IV from both E. coli and S. aureus. The crystal structure of the 2-((2-(4,5-dibromo-1H-pyrrole-2-carboxamido)benzothiazol-6-yl)amino)-2-oxoacetic acid (24) in complex with E. coli DNA gyrase B revealed the binding mode of the inhibitor in the ATP-binding pocket. Only some compounds possessed weak antibacterial activity against Gram-positive bacteria. These results provide a basis for structure-based optimization toward dual DNA gyrase and topoisomerase IV inhibitors with antibacterial activity.

Numerous compounds with a benzothiazole scaffold that have been described in the literature show promising activities against several Gram-positive and Gram-negative bacteria, and also against Mycobacterium tuberculosis. Benzothiazole-based antibacterial compounds bind to different biological targets in bacterial cells and have been shown to be inhibitors of enzymes that are important for essential processes in the bacterial cells, such as cell-wall synthesis, cell division, and DNA replication, or are important for different biosynthetic pathways of essential compounds in bacterial cells, such as the biosynthesis of histidine and biotin. This review focuses on the antibacterial potential of benzothiazole-based compounds, in terms of their specific interactions with targets in bacterial cells. We assess the importance of the benzothiazole scaffold in the discovery of new antibacterial compounds, the potential of benzothiazole-based compounds against resistant bacterial strains, optimization of their antibacterial activity, and the future perspectives of benzothiazole-based antibacterials.

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