ABSTRACT
Fragment-based lead discovery has emerged over the last decades as one of the most powerful techniques for identifying starting chemical matter to target specific proteins or nucleic acids in vitro. However, the use of such low-molecular-weight fragment molecules in cell-based phenotypic assays has been historically avoided because of concerns that bioassays would be insufficiently sensitive to detect the limited potency expected for such small molecules and that the high concentrations required would likely implicate undesirable artifacts. Herein, we applied phenotype cell-based screens using a curated fragment library to identify inhibitors against a range of pathogens including Leishmania, Plasmodium falciparum, Neisseria, Mycobacterium, and flaviviruses. This proof-of-concept shows that fragment-based phenotypic lead discovery (FPLD) can serve as a promising complementary approach for tackling infectious diseases and other drug-discovery programs.
Subject(s)
Anti-Infective Agents/chemistry , Anti-Infective Agents/pharmacology , Drug Discovery , Drug Evaluation, Preclinical , Structure-Activity RelationshipABSTRACT
The re-emergence of tuberculosis in recent years led the World Health Organization (WHO) to launch the Stop TB Strategy program. Beside repurposing the existing drugs and exploring novel molecular combinations, an essential step to face the burden of tuberculosis will be to develop new drugs by identifying vulnerable bacterial targets. Recent studies have focused on decaprenylphosphoryl-D-ribose oxidase (DprE1) of Mycobacterium tuberculosis, an essential enzyme involved in cell wall metabolism, for which new promising molecules have proved efficacy as antitubercular agents. This review summarizes the state of the art concerning DprE1 in terms of structure, enzymatic activity and inhibitors. This enzyme is emerging as one of the most vulnerable target in M. tuberculosis.
Subject(s)
Bacterial Proteins/antagonists & inhibitors , Enzyme Inhibitors/pharmacology , Mycobacterium tuberculosis/enzymology , Oxidoreductases/antagonists & inhibitors , Tuberculosis/drug therapy , Alcohol Oxidoreductases , Animals , Bacterial Proteins/chemistry , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , Cell Wall/drug effects , Cell Wall/genetics , Cell Wall/metabolism , Drug Evaluation, Preclinical , Enzyme Inhibitors/chemistry , Humans , Mycobacterium tuberculosis/chemistry , Mycobacterium tuberculosis/drug effects , Mycobacterium tuberculosis/genetics , Oxidoreductases/chemistry , Oxidoreductases/genetics , Oxidoreductases/metabolism , Tuberculosis/microbiologyABSTRACT
New drugs are required to counter the tuberculosis (TB) pandemic. Here, we describe the synthesis and characterization of 1,3-benzothiazin-4-ones (BTZs), a new class of antimycobacterial agents that kill Mycobacterium tuberculosis in vitro, ex vivo, and in mouse models of TB. Using genetics and biochemistry, we identified the enzyme decaprenylphosphoryl-beta-d-ribose 2'-epimerase as a major BTZ target. Inhibition of this enzymatic activity abolishes the formation of decaprenylphosphoryl arabinose, a key precursor that is required for the synthesis of the cell-wall arabinans, thus provoking cell lysis and bacterial death. The most advanced compound, BTZ043, is a candidate for inclusion in combination therapies for both drug-sensitive and extensively drug-resistant TB.
Subject(s)
Antitubercular Agents/pharmacology , Antitubercular Agents/therapeutic use , Mycobacterium tuberculosis/drug effects , Polysaccharides/biosynthesis , Racemases and Epimerases/antagonists & inhibitors , Spiro Compounds/pharmacology , Spiro Compounds/therapeutic use , Thiazines/pharmacology , Thiazines/therapeutic use , Tuberculosis/drug therapy , Amino Acid Sequence , Animals , Antitubercular Agents/chemical synthesis , Antitubercular Agents/chemistry , Arabinose/metabolism , Cell Wall/metabolism , Drug Resistance, Bacterial , Enzyme Inhibitors/cerebrospinal fluid , Enzyme Inhibitors/chemistry , Enzyme Inhibitors/pharmacology , Enzyme Inhibitors/therapeutic use , Ethambutol/pharmacology , Gene Expression Regulation, Bacterial/drug effects , Genes, Bacterial , Mice , Mice, Inbred BALB C , Microbial Sensitivity Tests , Molecular Sequence Data , Molecular Structure , Mycobacterium/drug effects , Mycobacterium/genetics , Mycobacterium tuberculosis/genetics , Mycobacterium tuberculosis/metabolism , Racemases and Epimerases/metabolism , Spiro Compounds/chemical synthesis , Spiro Compounds/chemistry , Thiazines/chemical synthesis , Thiazines/chemistry , Tuberculosis/microbiologyABSTRACT
Tuberculosis (TB) remains the leading cause of mortality due to a bacterial pathogen, Mycobacterium tuberculosis. Moreover, the recent isolation of M. tuberculosis strains resistant to both first- and second-line antitubercular drugs (XDR-TB) threatens to make the treatment of this disease extremely difficult and becoming a threat to public health worldwide. Recently, it has been shown that azoles are potent inhibitors of mycobacterial cell growth and have antitubercular activity in mice, thus favoring the hypothesis that these drugs may constitute a novel strategy against tuberculosis disease. To investigate the mechanisms of resistance to azoles in mycobacteria, we isolated and characterized several spontaneous azoles resistant mutants from M. tuberculosis and Mycobacterium bovis BCG. All the analyzed resistant mutants exhibited both increased econazole efflux and increased transcription of mmpS5-mmpL5 genes, encoding a hypothetical efflux system belonging to the resistance-nodulation-division (RND) family of transporters. We found that the up-regulation of mmpS5-mmpL5 genes was linked to mutations either in the Rv0678 gene, hypothesized to be involved in the transcriptional regulation of this efflux system, or in its putative promoter/operator region.