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.

Multidrug resistant Staphylococcus aureus is a severe threat, responsible for most of the nosocomial infections globally. This resistant strain is associated with a 64% increase in death compared to the antibiotic-susceptible strain. The prokaryotic protein FtsZ and the cell division cycle have been validated as potential targets to exploit in the general battle against antibiotic resistance. Despite the discovery and development of several anti-FtsZ compounds, no FtsZ inhibitors are currently used in therapy. This work further develops benzodioxane-benzamide FtsZ inhibitors. We seek to find more potent compounds using computational studies, with encouraging predicted drug-like profiles. We report the synthesis and the characterization of novel promising derivatives that exhibit very low MICs towards both methicillin-susceptible and -resistant S. aureus, as well as another Gram positive species, Bacillus subtilis, while possessing good predicted physical-chemical properties in terms of solubility, permeability, and chemical and physical stability. In addition, we demonstrate by fluorescence microscopy that Z ring formation and FtsZ localization are strongly perturbed by our derivatives, thus validating the target.

More than 1 billion people live in areas endemic for leishmaniasis, which is a relevant threat for public health worldwide. Due to the inadequate treatments, there is an urgent need to develop novel alternative drugs and to validate new targets to fight this disease. One appealing approach is the selective inhibition of protein kinases (PKs), enzymes involved in a wide range of processes along the life cycle of Leishmania. Several PKs, including glycogen synthase kinase 3 (GSK-3), have been validated as essential for this parasite by genetic or pharmacological methods. Recently, novel chemical scaffolds have been uncovered as Leishmania GSK-3 inhibitors with antiparasitic activity. In order to find new inhibitors of this enzyme, a virtual screening of our in-house chemical library was carried out on the structure of the Leishmania GSK-3. The virtual hits identified were experimentally assayed both for leishmanicidal activity and for in vitro inhibition of the enzyme. The best hits have a quinone scaffold. Their optimization through a medicinal chemistry approach led to a set of new compounds, provided a frame to establish biochemical and antiparasitic structure–activity relationships, and delivered molecules with an improved selectivity index. Altogether, this study paves the way for a systemic search of this class of inhibitors for further development as potential leishmanicidal drugs.

FtsZ is an essential bacterial protein abundantly studied as a novel and promising target for antimicrobials. FtsZ is highly conserved among bacteria and mycobacteria, and it is crucial for the correct outcome of the cell division process, as it is responsible for the division of the parent bacterial cell into two daughter cells. In recent years, the benzodioxane–benzamide class has emerged as very promising and capable of targeting both Gram-positive and Gram-negative FtsZs. In this study, we explored the effect of including a substituent on the ethylenic linker between the two main moieties on the antimicrobial activity and pharmacokinetic properties. This substitution, in turn, led to the generation of a second stereogenic center, with both erythro and threo isomers isolated, characterized, and evaluated. With this work, we discovered how the hydroxy group slightly affects the antimicrobial activity, while being an important anchor for the exploitation and development of prodrugs, probes, and further derivatives.

Antibiotic resistance is spreading worldwide and it has become one of the most important issues in modern medicine. In this context, the bacterial RNA degradation and processing machinery are essential processes for bacterial viability that may be exploited for antimicrobial therapy. In Staphylococcus aureus, RnpA has been hypothesized to be one of the main players in these mechanisms. S. aureus RnpA is able to modulate mRNA degradation and complex with a ribozyme (rnpB), facilitating ptRNA maturation. Corresponding small molecule screening campaigns have recently identified a few classes of RnpA inhibitors, and their structure activity relationship (SAR) has only been partially explored. Accordingly, in the present work, using computational modeling of S. aureus RnpA we identified putative crucial interactions of known RnpA inhibitors, and we used this information to design, synthesize, and biologically assess new potential RnpA inhibitors. The present results may be beneficial for the overall knowledge about RnpA inhibitors belonging to both RNPA2000-like thiosemicarbazides and JC-like piperidine carboxamides molecular classes. We evaluated the importance of the different key moieties, such as the dichlorophenyl and the piperidine of JC2, and the semithiocarbazide, the furan, and the i-propylphenyl ring of RNPA2000. Our efforts could provide a foundation for further computational-guided investigations.