ABSTRACT
Fluorination of metabolic hotspots in a molecule is a common medicinal chemistry strategy to improve in vivo half-life and exposure and, generally, this strategy offers significant benefits. Here, we report the application of this strategy to a series of poly-ADP ribose glycohydrolase (PARG) inhibitors, resulting in unexpected in vivo toxicity which was attributed to this single-atom modification.
Subject(s)
Cyclopropanes/pharmacology , Glycoside Hydrolases/toxicity , Microsomes, Liver/drug effects , Administration, Oral , Animals , Cyclopropanes/administration & dosage , Cyclopropanes/chemistry , Cyclopropanes/pharmacokinetics , Glycoside Hydrolases/administration & dosage , Glycoside Hydrolases/chemistry , Glycoside Hydrolases/pharmacokinetics , Half-Life , Humans , Mice , Microsomes, Liver/metabolismABSTRACT
DNA damage repair enzymes are promising targets in the development of new therapeutic agents for a wide range of cancers and potentially other diseases. The enzyme poly(ADP-ribose) glycohydrolase (PARG) plays a pivotal role in the regulation of DNA repair mechanisms; however, the lack of potent drug-like inhibitors for use in cellular and in vivo models has limited the investigation of its potential as a novel therapeutic target. Using the crystal structure of human PARG in complex with the weakly active and cytotoxic anthraquinone 8a, novel quinazolinedione sulfonamides PARG inhibitors have been identified by means of structure-based virtual screening and library design. 1-Oxetan-3-ylmethyl derivatives 33d and 35d were selected for preliminary investigations in vivo. X-ray crystal structures help rationalize the observed structure-activity relationships of these novel inhibitors.
Subject(s)
DNA Repair , Drug Design , Glycoside Hydrolase Inhibitors/chemistry , Glycoside Hydrolase Inhibitors/pharmacology , Glycoside Hydrolases/antagonists & inhibitors , Quinazolinones/chemistry , Quinazolinones/pharmacology , Administration, Oral , Animals , Biological Availability , Catalytic Domain , Glycoside Hydrolase Inhibitors/administration & dosage , Glycoside Hydrolase Inhibitors/pharmacokinetics , Glycoside Hydrolases/chemistry , Glycoside Hydrolases/metabolism , HeLa Cells , Humans , Male , Mice , Models, Molecular , Quinazolinones/administration & dosage , Quinazolinones/pharmacokinetics , Structure-Activity RelationshipABSTRACT
A series of reversible inhibitors of lysine specific demethylase 1 (LSD1) with a 5-hydroxypyrazole scaffold have been developed from compound 7, which was identified from the patent literature. Surface plasmon resonance (SPR) and biochemical analysis showed it to be a reversible LSD1 inhibitor with an IC50 value of 0.23µM. Optimisation of this compound by rational design afforded compounds with Kd values of <10nM. In human THP-1 cells, these compounds were found to upregulate the expression of the surrogate cellular biomarker CD86. Compound 11p was found to have moderate oral bioavailability in mice suggesting its potential for use as an in vivo tool compound.
Subject(s)
Histone Demethylases/antagonists & inhibitors , Pyrazoles/chemistry , Animals , B7-2 Antigen/metabolism , Binding Sites , Catalytic Domain , Cell Differentiation/drug effects , Cell Line , Half-Life , Histone Demethylases/metabolism , Humans , Inhibitory Concentration 50 , Mice , Molecular Docking Simulation , Pyrazoles/chemical synthesis , Pyrazoles/pharmacokinetics , Pyrazoles/pharmacology , Structure-Activity Relationship , Surface Plasmon ResonanceABSTRACT
We have previously reported a series of anilinoquinazoline derivatives as potent and selective biochemical inhibitors of the RET kinase domain. However, these derivatives displayed diminished cellular potency. Herein we describe further optimisation of the series through modification of their physicochemical properties, delivering improvements in cell potency. However, whilst cellular selectivity against key targets could be maintained, combining cell potency and acceptable pharmacokinetics proved challenging.
Subject(s)
Aniline Compounds/pharmacology , Protein Kinase Inhibitors/pharmacology , Proto-Oncogene Proteins c-ret/antagonists & inhibitors , Quinazolines/pharmacology , Aniline Compounds/chemical synthesis , Aniline Compounds/chemistry , Dose-Response Relationship, Drug , Humans , Models, Molecular , Molecular Structure , Protein Kinase Inhibitors/chemical synthesis , Protein Kinase Inhibitors/chemistry , Proto-Oncogene Proteins c-ret/metabolism , Quinazolines/chemical synthesis , Quinazolines/chemistry , Structure-Activity RelationshipABSTRACT
Deregulation of the receptor tyrosine kinase RET has been implicated in medullary thyroid cancer, a small percentage of lung adenocarcinomas, endocrine-resistant breast cancer and pancreatic cancer. There are several clinically approved multi-kinase inhibitors that target RET as a secondary pharmacology but additional activities, most notably inhibition of KDR, lead to dose-limiting toxicities. There is, therefore, a clinical need for more specific RET kinase inhibitors. Herein we report our efforts towards identifying a potent and selective RET inhibitor using vandetanib 1 as the starting point for structure-based drug design. Phenolic anilinoquinazolines exemplified by 6 showed improved affinities towards RET but, unsurprisingly, suffered from high metabolic clearance. Efforts to mitigate the metabolic liability of the phenol led to the discovery that a flanking substituent not only improved the hepatocyte stability, but could also impart a significant gain in selectivity. This culminated in the identification of 36; a potent RET inhibitor with much improved selectivity against KDR.
Subject(s)
Piperidines/chemistry , Piperidines/pharmacology , Protein Kinase Inhibitors/chemistry , Protein Kinase Inhibitors/pharmacology , Proto-Oncogene Proteins c-ret/antagonists & inhibitors , Quinazolines/chemistry , Quinazolines/pharmacology , Animals , Cell Line , Drug Design , Humans , Mice , Molecular Docking Simulation , Piperidines/pharmacokinetics , Protein Kinase Inhibitors/pharmacokinetics , Proto-Oncogene Proteins c-ret/metabolism , Quinazolines/pharmacokineticsABSTRACT
The recently discovered enzyme tyrosyl-DNA phosphodiesterase 2 (TDP2) has been implicated in the topoisomerase-mediated repair of DNA damage. In the clinical setting, it has been hypothesized that TDP2 may mediate drug resistance to topoisomerase II (topo II) inhibition by etoposide. Therefore, selective pharmacological inhibition of TDP2 is proposed as a novel approach to overcome intrinsic or acquired resistance to topo II-targeted drug therapy. Following a high-throughput screening (HTS) campaign, toxoflavins and deazaflavins were identified as the first reported sub-micromolar and selective inhibitors of this enzyme. Toxoflavin derivatives appeared to exhibit a clear structure-activity relationship (SAR) for TDP2 enzymatic inhibition. However, we observed a key redox liability of this series, and this, alongside early in vitro drug metabolism and pharmacokinetics (DMPK) issues, precluded further exploration. The deazaflavins were developed from a singleton HTS hit. This series showed distinct SAR and did not display redox activity; however low cell permeability proved to be a challenge.
Subject(s)
Phosphoric Diester Hydrolases/drug effects , Pyrimidinones/pharmacology , Topoisomerase II Inhibitors/pharmacology , Triazines/pharmacology , Structure-Activity Relationship , Topoisomerase II Inhibitors/chemistryABSTRACT
Novel derivatives of the steroid DHEA 1, a known uncompetitive inhibitor of G6PD, were designed, synthesized, and tested for their ability to inhibit this dehydrogenase enzyme. Several compounds with approximately 10-fold improved potency in an enzyme assay were identified, and this improved activity translated to efficacy in a cellular assay. The SAR for steroid inhibition of G6PD has been substantially developed; the 3ß-alcohol can be replaced with 3ß-H-bond donors such as sulfamide, sulfonamide, urea, and carbamate. Improved potency was achieved by replacing the androstane nucleus with a pregnane nucleus, provided a ketone at C-20 is present. For pregnan-20-ones incorporation of a 21-hydroxyl group is often beneficial. The novel compounds generally have good physicochemical properties and satisfactory in vitro DMPK parameters. These derivatives may be useful for examining the role of G6PD inhibition in cells and will assist the future design of more potent steroid inhibitors with potential therapeutic utility.
