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In search of novel drugs against tuberculosis, we previously discovered and profiled a novel hydantoin-based family that demonstrated highly promising in vitro potency against M. tuberculosis. The compounds were found to be non-covalent inhibitors of DprE1, a subunit of decaprenylphosphoryl-β-D-ribose-2′-epimerase. This protein, localized in the periplasmic space of the mycobacterial cell wall, was shown to be an essential and vulnerable antimycobacterial drug target. Here, we report the further SAR exploration of this chemical family through more than 80 new analogues. Among these, the most active representatives combined sub-micromolar cellular potency and nanomolar target affinity with balanced physicochemical properties and low human cytotoxicity. Moreover, we demonstrate in vivo activity in an acute Mtb infection model and provide further proof of DprE1 being the target of the hydantoins. Overall, the hydantoin family of DprE1 inhibitors represents a promising non-covalent lead series for the discovery of novel antituberculosis agents.

Screening of a GSK-proprietary library against intracellular Mycobacterium tuberculosis identified 1, a thioalkylbenzoxazole hit. Biological profiling and mutant analysis revealed that this compound is a prodrug that is bioactivated by the mycobacterial enzyme MymA. A hit-expansion program including design, synthesis, and profiling of a defined set of analogues with optimized drug-like properties led to the identification of an emerging lead compound, displaying potency against intracellular bacteria in the low micromolar range, high in vitro solubility and permeability, and excellent microsomal stability.

Shiga toxin is an AB5 toxin produced by Shigella species, while related toxins are produced by Shiga toxin-producing Escherichia coli (STEC). Infection by Shigella can lead to bloody diarrhea followed by the often fatal hemolytic uremic syndrome (HUS). In the present paper, we aimed for a simple and effective toxin inhibitor by comparing three classes of carbohydrate-based inhibitors: glycodendrimers, glycopolymers, and oligosaccharides. We observed a clear enhancement in potency for multivalent inhibitors, with the divalent and tetravalent compounds inhibiting in the millimolar and micromolar range, respectively. However, the polymeric inhibitor based on galabiose was the most potent in the series exhibiting nanomolar inhibition. Alginate and chitosan oligosaccharides also inhibit Shiga toxin and may be used as a prophylactic drug during shigella outbreaks.

Screening of a GSK-proprietary library against intracellular

Tuberculosis is the leading cause of death worldwide from infectious diseases. With the development of drug-resistant strains of Mycobacterium tuberculosis, there is an acute need for new medicines with novel modes of action. Herein, we report the discovery and profiling of a novel hydantoin-based family of antimycobacterial inhibitors of the decaprenylphospho-β-d-ribofuranose 2-oxidase (DprE1). In this study, we have prepared a library of more than a 100 compounds and evaluated them for their biological and physicochemical properties. The series is characterized by high enzymatic and whole-cell activity, low cytotoxicity, and a good overall physicochemical profile. In addition, we show that the series acts via reversible inhibition of the DprE1 enzyme. Overall, the novel compound family forms an attractive base for progression to further stages of optimization and may provide a promising drug candidate in the future.

In this study, a new series of more than 60 quinoline derivatives has been synthesized and evaluated against Mycobacterium tuberculosis (H37Rv). Apart from the SAR exploration around the initial hits, the optimization process focused on the improvement of the physicochemical properties, cytotoxicity, and metabolic stability of the series. The best compounds obtained exhibited MIC values in the low micromolar range, excellent intracellular antimycobacterial activity, and an improved physicochemical profile without cytotoxic effects. Further investigation revealed that the amide bond was the source for the poor blood stability observed, while some of the compounds exhibited hERG affinity. Compound 83 which contains a benzoxazole ring instead of the amide group was found to be a good alternative, with good blood stability and no hERG affinity, providing new opportunities for the series. Overall, the obtained results suggest that further optimization of solubility and microsomal stability of the series could provide a strong lead for a new anti-TB drug development program.