Linking High-Throughput Screens to Identify MoAs and Novel Inhibitors of <i>Mycobacterium tuberculosis</i> Dihydrofolate Reductase

Though phenotypic and target-based high-throughput screening approaches have been employed to discover new antibiotics, the identification of promising therapeutic candidates remains challenging. Each approach provides different information, and understanding their results can provide hypotheses for a mechanism of action (MoA) and reveal actionable chemical matter. Here, we describe a framework for identifying efficacy targets of bioactive compounds. High throughput biophysical profiling against a broad range of targets coupled with machine learning was employed to identify chemical features with predicted efficacy targets for a given phenotypic screen. We validate the approach on data from a set of 55 000 compounds in 24 historical internal antibacterial phenotypic screens and 636 bacterial targets screened in high-throughput biophysical binding assays. Models were built to reveal the relationships between phenotype, target, and chemotype, which recapitulated mechanisms for known antibacterials. We also prospectively identified novel inhibitors of dihydrofolate reductase with nanomolar antibacterial efficacy against <i>Mycobacterium tuberculosis</i>. Molecular modeling provided structural insight into target–ligand interactions underlying selective killing activity toward mycobacteria over human cells

Stimulation of Glucose-Dependent Insulin Secretion by a Potent, Selective sst₃ Antagonist

This letter provides the first pharmacological proof of principle that the sst₃ receptor mediates glucose-stimulated insulin secretion (GSIS) from pancreatic β-cells. To enable these studies, we identified the selective sst₃ antagonist (1<i>R</i>,3<i>R</i>)-3-(5-phenyl-1<i>H</i>-imidazol-2-yl)-1-(tetrahydro-2<i>H</i>-pyran-4-yl)-2,3,4,9-tetrahydro-1<i>H</i>-β-carboline (<b>5a</b>), with improved ion channel selectivity and mouse pharmacokinetic properties as compared to previously described tetrahydro-β-carboline imidazole sst3 antagonists. We demonstrated that compound <b>5a</b> enhances GSIS in pancreatic β-cells and blocks glucose excursion induced by dextrose challenge in ipGTT and OGTT models in mice. Finally, we provided strong evidence that these effects are mechanism-based in an ipGTT study, showing reduction of glucose excursion in wild-type but not sst₃ knockout mice. Thus, we have shown that antagonism of sst₃ represents a new mechanism with potential in treating type 2 diabetes mellitus

Discovery of a Potent and Selective ROMK Inhibitor with Pharmacokinetic Properties Suitable for Preclinical Evaluation

A new subseries of ROMK inhibitors exemplified by <b>28</b> has been developed from the initial screening hit <b>1</b>. The excellent selectivity for ROMK inhibition over related ion channels and pharmacokinetic properties across preclinical species support further preclinical evaluation of <b>28</b> as a new mechanism diuretic. Robust pharmacodynamic effects in both SD rats and dogs have been demonstrated

The Discovery of MK-4256, a Potent SSTR3 Antagonist as a Potential Treatment of Type 2 Diabetes

A structure–activity relationship study of the imidazolyl-β-tetrahydrocarboline series identified MK-4256 as a potent, selective SSTR3 antagonist, which demonstrated superior efficacy in a mouse oGTT model. MK-4256 reduced glucose excursion in a dose-dependent fashion with maximal efficacy achieved at doses as low as 0.03 mg/kg po. As compared with glipizide, MK-4256 showed a minimal hypoglycemia risk in mice