8 research outputs found
Structurally diverse mitochondrial branched chain aminotransferase (BCATm) leads with varying binding modes identified by fragment screening
Inhibitors of mitochondrial branched chain aminotransferase (BCATm), identified using fragment screening, are described. This was carried out using a combination of STD-NMR, thermal melt (Tm), and biochemical assays to identify compounds that bound to BCATm, which were subsequently progressed to X-ray crystallography, where a number of exemplars showed significant diversity in their binding modes. The hits identified were supplemented by searching and screening of additional analogues, which enabled the gathering of further X-ray data where the original hits had not produced liganded structures. The fragment hits were optimized using structure-based design, with some transfer of information between series, which enabled the identification of ligand efficient lead molecules with micromolar levels of inhibition, cellular activity, and good solubility
Development of a Series of Kynurenine 3-Monooxygenase Inhibitors Leading to a Clinical Candidate for the Treatment of Acute Pancreatitis
Recently,
we reported a novel role for KMO in the pathogenesis
of acute pancreatitis (AP). A number of inhibitors of kynurenine 3-monooxygenase
(KMO) have previously been described as potential treatments for neurodegenerative
conditions and particularly for Huntingtonâs disease. However,
the inhibitors reported to date have insufficient aqueous solubility
relative to their cellular potency to be compatible with the intravenous
(iv) dosing route required in AP. We have identified and optimized
a novel series of high affinity KMO inhibitors with favorable physicochemical
properties. The leading example is exquisitely selective, has low
clearance in two species, prevents lung and kidney damage in a rat
model of acute pancreatitis, and is progressing into preclinical development
Kynurenineâ3âmonooxygenase inhibition prevents multiple organ failure in rodent models of acute pancreatitis
Acute pancreatitis (AP) is a common and devastating inflammatory condition of the pancreas that is considered to be a paradigm of sterile inflammation leading to systemic multiple organ dysfunction syndrome (MODS) and death1,2 Acute mortality from AP-MODS exceeds 20%3 and for those who survive the initial episode, their lifespan is typically shorter than the general population4. There are no specific therapies available that protect individuals against AP-MODS. Here, we show that kynurenine-3-monooxygenase (KMO), a key enzyme of tryptophan metabolism5, is central to the pathogenesis of AP-MODS. We created a mouse strain deficient for Kmo with a robust biochemical phenotype that protected against extrapancreatic tissue injury to lung, kidney and liver in experimental AP-MODS. A medicinal chemistry strategy based on modifications of the kynurenine substrate led to the discovery of GSK180 as a potent and specific inhibitor of KMO. The binding mode of the inhibitor in the active site was confirmed by X-ray co-crystallography at 3.2 Ă
resolution. Treatment with GSK180 resulted in rapid changes in levels of kynurenine pathway metabolites in vivo and afforded therapeutic protection against AP-MODS in a rat model of AP. Our findings establish KMO inhibition as a novel therapeutic strategy in the treatment of AP-MODS and open up a new area for drug discovery in critical illness
Supporting Information Homotrimerization Approach in the Design of Thrombospondin-1 Mimetic Peptides with Improved Potency in Triggering Regulated Cell Death of Cancer Cells
International audienceIn order to optimize the potency of the first serum-stable peptide agonist of CD47 (PKHB1) in triggering regulated cell death of cancer cells, we designed a maturation process aimed to mimic the trimeric structure of the thrombospondin-1/CD47 binding epitope. For that purpose, an N-methylation scan of the PKHB1 sequence was realized to prevent peptide aggregation. Structural and pharmacological analyses were conducted in order to assess the conformational impact of these chemical modifications on the backbone structure and the biological activity. This structureâactivity relationship study led to the discovery of a highly soluble N-methylated peptide that we termed PKT16. Afterward, this monomer was used for the design of a homotrimeric peptide mimic that we termed [PKT16]3, which proved to be 10-fold more potent than its monomeric counterpart. A pharmacological evaluation of [PKT16]3 in inducing cell death of adherent (A549) and nonadherent (MEC-1) cancer cell lines was also performed
The discovery of in vivo active mitochondrial branched-chain aminotransferase (BCATm) inhibitors by hybridizing fragment and HTS hits
The hybridization of hits, identified by complementary fragment and high throughput screens, enabled the discovery of the first series of potent inhibitors of mitochondrial branched-chain aminotransferase (BCATm) based on a 2-benzylamino-pyrazolo[1,5-a]pyrimidinone-3-carbonitrile template. Structure-guided growth enabled rapid optimization of potency with maintenance of ligand efficiency, while the focus on physicochemical properties delivered compounds with excellent pharmacokinetic exposure that enabled a proof of concept experiment in mice. Oral administration of 2-((4-chloro-2,6-difluorobenzyl)amino)-7-oxo-5-propyl-4,7-dihydropyrazolo[1,5-a]pyrimidine-3-carbonitrile 61 significantly raised the circulating levels of the branched-chain amino acids leucine, isoleucine, and valine in this acute study
Discovery and Optimization of Potent, Selective, and <i>in Vivo</i> Efficacious 2âAryl Benzimidazole BCATm Inhibitors
To
identify BCATm inhibitors suitable for <i>in vivo</i> study,
Encoded Library Technology (ELT) was used to affinity screen
a 117 million member benzimidazole based DNA encoded library, which
identified an inhibitor series with both biochemical and cellular
activities. Subsequent SAR studies led to the discovery of a highly
potent and selective compound, 1-(3-(5-bromothiophene-2-carboxamido)Âcyclohexyl)-<i>N</i>-methyl-2-(pyridin-2-yl)-1<i>H</i>-benzoÂ[d]Âimidazole-5-carboxamide
(<b>8b</b>) with much improved PK properties. X-ray structure
revealed that <b>8b</b> binds to the active site of BACTm in
a unique mode via multiple H-bond and van der Waals interactions.
After oral administration, <b>8b</b> raised mouse blood levels
of all three branched chain amino acids as a consequence of BCATm
inhibition
Discovery, SAR, and Xâray Binding Mode Study of BCATm Inhibitors from a Novel DNA-Encoded Library
As a potential target for obesity,
human BCATm was screened against
more than 14 billion DNA encoded compounds of distinct scaffolds followed
by off-DNA synthesis and activity confirmation. As a consequence,
several series of BCATm inhibitors were discovered. One representative
compound (<i>R</i>)-3-((1-(5-bromothiophene-2-carbonyl)Âpyrrolidin-3-yl)Âoxy)-<i>N</i>-methyl-2âČ-(methylsulfonamido)-[1,1âČ-biphenyl]-4-carboxamide
(<b>15e</b>) from a novel compound library synthesized via on-DNA
SuzukiâMiyaura cross-coupling showed BCATm inhibitory activity
with IC<sub>50</sub> = 2.0 ÎŒM. A protein crystal structure of <b>15e</b> revealed that it binds to BCATm within the catalytic site
adjacent to the PLP cofactor. The identification of this novel inhibitor
series plus the establishment of a BCATm protein structure provided
a good starting point for future structure-based discovery of BCATm
inhibitors