FtsZ is a crucial prokaryotic protein involved in bacterial cell replication. It recently arose as a promising target in the search for antimicrobial agents able to fight antimicrobial resistance. In this work, going on with our structure‐activity relationship (SAR) study, we developed variously 7‐substituted 1,4‐benzodioxane compounds, linked to the 2,6‐difluorobenzamide by a methylenoxy bridge. Compounds exhibit promising antibacterial activities not only against multidrug‐resistant Staphylococcus aureus, but also on mutated Escherichia coli strains, thus enlarging their spectrum of action toward Gram‐negative bacteria as well. Computational studies elucidated, through a validated FtsZ binding protocol, the structural features of new promising derivatives as FtsZ inhibitors.

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Binary fission is the most common mode of bacterial cell division and is mediated by a multiprotein complex denominated the divisome. The constriction of the Z-ring splits the mother bacterial cell into two daughter cells of the same size. The Z-ring is formed by the polymerization of FtsZ, a bacterial protein homologue of eukaryotic tubulin, and it represents the first step of bacterial cytokinesis. The high grade of conservation of FtsZ in most prokaryotic organisms and its relevance in orchestrating the whole division system make this protein a fascinating target in antibiotic research. Indeed, FtsZ inhibition results in the complete blockage of the division system and, consequently, in a bacteriostatic or a bactericidal effect. Since many papers and reviews already discussed the physiology of FtsZ and its auxiliary proteins, as well as the molecular mechanisms in which they are involved, here, we focus on the discussion of the most compelling FtsZ inhibitors, classified by their main protein binding sites and following a medicinal chemistry approach.

Filamentous temperature-sensitive Z (FtsZ) is a prokaryotic protein with an essential role in the bacterial cell division process. It is widely conserved and expressed in both Gram-positive and Gram-negative strains. In the last decade, several research groups have pointed out molecules able to target FtsZ in Staphylococcus aureus, Bacillus subtilis and other Gram-positive strains, with sub-micromolar Minimum Inhibitory Concentrations (MICs). Conversely, no promising derivatives active on Gram-negatives have been found up to now. Here, we report our results on a class of benzamide compounds, which showed comparable inhibitory activities on both S. aureus and Escherichia coli FtsZ, even though they proved to be substrates of E. coli efflux pump AcrAB, thus affecting the antimicrobial activity. These surprising results confirmed how a single molecule can target both species while maintaining potent antimicrobial activity. A further computational study helped us decipher the structural features necessary for broad spectrum activity and assess the drug-like profile and the on-target activity of this family of compounds.

A wide variety of drug‐resistant microorganisms are continuously emerging, restricting the therapeutic options for common bacterial infections. Antimicrobial agents that were originally potent are now no longer helpful, due to their weak or null activity toward these antibiotic‐resistant bacteria. In addition, none of the recently approved antibiotics affect innovative targets, resulting in a need for novel drugs with innovative antibacterial mechanisms of action. The essential cell division protein filamentous temperature‐sensitive Z (FtsZ) has emerged as a possible target, thanks to its ubiquitous expression and its homology to eukaryotic β‐tubulin. In the latest years, several compounds were shown to interact with this prokaryotic protein and selectively inhibit bacterial cell division. Recently, our research group developed interesting derivatives displaying good antibacterial activities against methicillin‐resistant Staphylococcus aureus, as well as vancomycin‐resistant Enterococcus faecalis and Mycobacterium tuberculosis. The aim of the present study was to summarize the structure–activity relationships of differently substituted heterocycles, linked by a methylenoxy bridge to the 2,6‐difluorobenzamide, and to validate FtsZ as the real target of this class of antimicrobials.