Publications by authors named "Ralph P Robinson"

The 2020 SARS-CoV-2 coronavirus pandemic highlighted the urgent need for novel small molecule antiviral drugs. (S)- DNDI-6510 is a non-covalent SARS-CoV-2 main protease inhibitor developed by the open science collaboration COVID Moonshot. Here, we report on the metabolic and toxicologic optimization of the lead series previously disclosed by the COVID Moonshot Initiative, leading up to the selection of (S)- DNDI-6510 as the preclinical candidate.

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  • - The COVID Moonshot was a collaborative, open-science effort focused on finding a new drug to inhibit the SARS-CoV-2 main protease, which is crucial for the virus's survival.
  • - Researchers developed a novel noncovalent, nonpeptidic inhibitor that stands out from existing drugs targeting the same protease, employing advanced techniques like machine learning and high-throughput structural biology.
  • - Over 18,000 compound designs, 490 ligand-bound x-ray structures, and extensive assay data were generated and shared openly, creating a comprehensive and accessible knowledge base for future drug discovery efforts against coronaviruses.
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Sickle cell disease (SCD) is a genetic disorder caused by a single point mutation (β6 Glu → Val) on the β-chain of adult hemoglobin (HbA) that results in sickled hemoglobin (HbS). In the deoxygenated state, polymerization of HbS leads to sickling of red blood cells (RBC). Several downstream consequences of polymerization and RBC sickling include vaso-occlusion, hemolytic anemia, and stroke.

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Ongoing interest in the discovery of selective JAK3 inhibitors led us to design novel covalent inhibitors that engage the JAK3 residue Cys909 by cyanamide, a structurally and mechanistically differentiated electrophile from other cysteine reacting groups previously incorporated in JAK3 covalent inhibitors. Through crystallography, kinetic, and computational studies, interaction of cyanamide 12 with Cys909 was optimized leading to potent and selective JAK3 inhibitors as exemplified by 32. In relevant cell-based assays and in agreement with previous results from this group, 32 demonstrated that selective inhibition of JAK3 is sufficient to drive JAK1/JAK3-mediated cellular responses.

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  • Janus kinases (JAKs) are key enzymes that play a role in managing the body's immune response, inflammation, and blood cell formation by mediating cytokine and growth factor signaling.
  • * Researchers focused on developing a selective JAK1 inhibitor to target inflammatory cytokines while sparing other functions regulated by JAK2, starting from the existing drug tofacitinib.
  • * Modifications to the chemical structure of tofacitinib led to the discovery of new JAK1 inhibitors, like PF-04965842, which showed strong effectiveness in models of autoimmune disease and have been proposed for clinical trials.
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  • - This text discusses the use of irreversible enzyme inhibitors and covalent probes that typically target cysteine residues in proteins, highlighting the need for alternatives when cysteine is unavailable.
  • - The authors previously focused on targeting tyrosine residues in a specific protein (DcpS) with sulfonyl fluoride inhibitors, paving the way for new probe technologies in living cells.
  • - They introduce a new compound, aryl fluorosulfate (FS-p1), which selectively reacts with a noncatalytic serine in DcpS and shows promise for developing new covalent inhibitors and chemical probes.
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Sulfonyl fluoride (SF)-based activity probes have become important tools in chemical biology. Herein, exploiting the relative chemical stability of SF to carry out a number of unprecedented SF-sparing functional group manipulations, we report the chemoselective synthesis of a toolbox of highly functionalized aryl SF monomers that we used to quickly prepare SF chemical biology probes. In addition to SF, the monomers bear an embedded click handle (a terminal alkyne that can perform copper(I)-mediated azide-alkyne cycloaddition).

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New advances in synthetic methodologies that allow rapid access to a wide variety of functionalized heterocyclic compounds are of critical importance to the medicinal chemist as it provides the ability to expand the available drug-like chemical space and drive more efficient delivery of drug discovery programs. Furthermore, the development of robust synthetic routes that can readily generate bulk quantities of a desired compound help to accelerate the drug development process. While established synthetic methodologies are commonly utilized during the course of a drug discovery program, the development of innovative heterocyclic syntheses that allow for different bond forming strategies are having a significant impact in the pharmaceutical industry.

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  • Photoaffinity labeling (PAL) is a useful technique in biology for studying protein interactions, but it's hard to create effective photoaffinity probes.
  • The authors developed a chemoproteomic library specifically to find a new photoaffinity probe for DcpS, an enzyme linked to Spinal Muscular Atrophy.
  • This method not only speeds up the discovery of probes but also enhances the available tools for studying RNA cap-binding proteins.
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A significant improvement in agonist activity of the previously described 2-aryloctahydrophenanthrene-2,3,7-triol series of dissociated glucocorticoid receptor agonists (DAGRs) was achieved by modifying the substitution at C3 from (S)-3-hydroxy to (R)-3-hydroxy-3-methyl. The IC50 of the prototype 13 in the efficacy assay measuring repression of IL-1 induced MMP-13 expression was 3.5 nM, exhibiting 87% of the maximal effect of dexamethasone (DEX).

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This work describes the first rational targeting of tyrosine residues in a protein binding site by small-molecule covalent probes. Specific tyrosine residues in the active site of the mRNA-decapping scavenger enzyme DcpS were modified using reactive sulfonyl fluoride covalent inhibitors. Structure-based molecular design was used to create an alkyne-tagged probe bearing the sulfonyl fluoride warhead, thus enabling the efficient capture of the protein from a complex proteome.

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A novel GPR119 agonist based on the 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazole scaffold was designed through lead optimization starting from pyrazole-based GPR119 agonist 1. The design is centered on the conformational restriction of the core scaffold, while minimizing the change in spatial relationships of two key pharmacophoric elements (piperidine-carbamate and aryl sulfone).

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Sodium-glucose co-transporter-2 (SGLT2) inhibitors are an emerging class of agents for use in the treatment of type 2 diabetes mellitus (T2DM). Inhibition of SGLT2 leads to improved glycemic control through increased urinary glucose excretion (UGE). In this study, a biologically based pharmacokinetic/pharmacodynamic (PK/PD) model of SGLT2 inhibitor-mediated UGE was developed.

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(1S,2S,3S,4R,5S)-5-[4-Chloro-3-(4-ethoxybenzyl)phenyl]-1-hydroxymethyl-6,8-dioxabicyclo[3.2.1]octane-2,3,4-triol (PF-04971729), a potent and selective inhibitor of the sodium-dependent glucose cotransporter 2, is currently in phase 2 trials for the treatment of diabetes mellitus.

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Analogues related to dirlotapide (1), a gut-selective inhibitor of microsomal triglyceride transfer protein (MTP) were prepared with the goal of further reducing the potential for unwanted liver MTP inhibition and associated side-effects. Compounds were designed to decrease active metabolite load: reducing MTP activity of likely human metabolites and increasing metabolite clearance to reduce exposure. Introduction of 4'-alkyl and 4'-alkoxy substituents afforded compounds exhibiting improved therapeutic index in rats with respect to liver triglyceride accumulation and enzyme elevation.

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Compound 4 (PF-04971729) belongs to a new class of potent and selective sodium-dependent glucose cotransporter 2 inhibitors incorporating a unique dioxa-bicyclo[3.2.1]octane (bridged ketal) ring system.

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The synthesis and properties of the bridged piperidine (oxaazabicyclo) compounds 8, 9, and 11 are described. A conformational analysis of these structures is compared with the representative GPR119 ligand 1. These results and the differences in agonist pharmacology are used to formulate a conformation-based hypothesis to understand activation of the GPR119 receptor.

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The design and synthesis of a GPR119 agonist bearing a 2-(2,3,6-trifluorophenyl)acetamide group is described. The design capitalized on the conformational restriction found in N-β-fluoroethylamide derivatives to help maintain good levels of potency while driving down both lipophilicity and oxidative metabolism in human liver microsomes. The chemical stability and bioactivation potential are discussed.

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Isopropyl 9-anti-[5-cyano-6-(2-methyl-pyridin-3-yloxy)-pyrimidin-4-yloxy]-3-oxa-7-aza-bicyclo[3.3.1]nonane-7-carboxylate (1) represents a prototypic compound from a lead chemical series of G protein-coupled receptor 119 agonists, intended for treatment of type 2 diabetes.

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Modifications to the sugar portion of C-aryl glycoside sodium glucose transporter 2 (SGLT2) inhibitors were explored, including systematic deletion and modification of each of the glycoside hydroxyl groups. Based on results showing activity to be quite tolerant of structural change at the C-5 position, a series of novel C-5 spiro analogues was prepared. Some of these analogues exhibit low nanomolar potency versus SGLT2 and promote urinary glucose excretion (UGE) in rats.

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As exemplified by the lead compound 2, octahydrophenanthrene-2,7-diol analogues exhibit the profile of a pathway-selective or "dissociated" agonist of the glucocorticoid receptor (GR), retaining the potent activity that glucocorticoids have for transrepression (as measured by inhibition of IL-1 induced MMP-13 expression) but showing an attenuated capacity for transactivation (as measured in an MMTV luciferase reporter assay). With the guidance of a homology model of the GR ligand binding domain, structural modifications to 2 were carried out that were successful in replacing the allyl and propynyl side chains with groups likely to be more chemically stable and less likely to produce toxic metabolites. Key to success was the introduction of an additional hydroxyl group onto the tricyclic carbon framework of the series.

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Through the use of computational modeling, a series of pyrimidinetrione-based inhibitors of MMP-13 was designed based on a lead inhibitor identified through file screening. Incorporation of a biaryl ether moiety at the C-5 position of the pyrimidinetrione ring resulted in a dramatic enhancement of MMP-13 potency. Protein crystallography revealed that this moiety binds in the S(1)(') pocket of the enzyme.

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The SAR of a series of sterically hindered sulfonamide hydroxamic acids with relatively large P1' groups is described. The compounds typically spare MMP-1 while being potent inhibitors of MMP-13. The metabolically more stable compounds in the series contain either a monocyclic or bicyclic pyran ring adjacent to the hydroxamate group.

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