David D. Wisnoski

RIP3 Induces Apoptosis Independent of Pronecrotic Kinase Activity

Receptor-interacting protein kinase 3 (RIP3 or RIPK3) has emerged as a central player in necroptosis and a potential target to control inflammatory disease. Here, three selective small-molecule compounds are shown to inhibit RIP3 kinase-dependent necroptosis, although their therapeutic value is undermined by a surprising, concentration-dependent induction of apoptosis. These compounds interact with RIP3 to activate caspase 8 (Casp8) via RHIM-driven recruitment of RIP1 (RIPK1) to assemble a Casp8-FADD-cFLIP complex completely independent of pronecrotic kinase activities and MLKL. RIP3 kinase-dead D161N mutant induces spontaneous apoptosis independent of compound, whereas D161G, D143N, and K51A mutants, like wild-type, only trigger apoptosis when compound is present. Accordingly, RIP3-K51A mutant mice (Rip3(K51A/K51A)) are viable and fertile, in stark contrast to the perinatal lethality of Rip3(D161N/D161N) mice. RIP3 therefore holds both necroptosis and apoptosis in balance through a Ripoptosome-like platform. This work highlights a common mechanism unveiling RHIM-driven apoptosis by therapeutic or genetic perturbation of RIP3.

Broadening the scope of 1,2,4-triazine synthesis by the application of microwave technology

By the application of microwave technology, a general protocol has been developed for the rapid synthesis of diverse 3,5,6-trisubstituted 1,2,4-triazines in excellent yield and purity, including many previously unknown 3-heterocyclic-1,2,4-triazines.

Discovery of 3-Aryl-4-isoxazolecarboxamides as TGR5 Receptor Agonists

A series of 3-aryl-4-isoxazolecarboxamides identified from a high-throughput screening campaign as novel, potent small molecule agonists of the human TGR5 G-protein coupled receptor is described. Subsequent optimization resulted in the rapid identification of potent exemplars 6 and 7 which demonstrated improved GLP-1 secretion in vivo via an intracolonic dose coadministered with glucose challenge in a canine model. These novel TGR5 receptor agonists are potentially useful therapeutics for metabolic disorders such as type II diabetes and its associated complications.

A ‘one pot’ microwave-mediated synthesis of the basic canthine skeleton: expedient access to unnatural β-carboline alkaloids

In a ‘one pot’ microwave reaction, an acyl hydrazide-tethered indole underwent a 3-component condensation to form a triazine, followed by an inverse-electron demand Diels–Alder reaction and subsequent chelotropic expulsion of N2 to deliver novel, unnatural β-carboline alkaloids in good isolated yields.

p38MAP kinase inhibitors. Part 1: design and development of a new class of potent and highly selective inhibitors based on 3,4-dihydropyrido[3,2-d]pyrimidone scaffold.

A new class of p38 antagonists based on 3,4-dihydropyrido[3,2,-d]pyrimidine scaffold has been developed. These inhibitors exhibit unprecedented selectivity towards p38 over other very closely related kinases. Compounds 25, 33, and 34 were identified as benchmark analogues for follow-up studies. They show good potency for enzyme inhibition and excellent functional activity.

Discovery of a First-in-Class Receptor Interacting Protein 1 (RIP1) Kinase Specific Clinical Candidate (GSK2982772) for the Treatment of Inflammatory Diseases

RIP1 regulates necroptosis and inflammation and may play an important role in contributing to a variety of human pathologies, including immune-mediated inflammatory diseases. Small-molecule inhibitors of RIP1 kinase that are suitable for advancement into the clinic have yet to be described. Herein, we report our lead optimization of a benzoxazepinone hit from a DNA-encoded library and the discovery and profile of clinical candidate GSK2982772 (compound 5), currently in phase 2a clinical studies for psoriasis, rheumatoid arthritis, and ulcerative colitis. Compound 5 potently binds to RIP1 with exquisite kinase specificity and has excellent activity in blocking many TNF-dependent cellular responses. Highlighting its potential as a novel anti-inflammatory agent, the inhibitor was also able to reduce spontaneous production of cytokines from human ulcerative colitis explants. The highly favorable physicochemical and ADMET properties of 5, combined with high potency, led to a predicted low oral dose in humans.

Parallel synthesis of N-biaryl quinolone carboxylic acids as selective M1 positive allosteric modulators

An iterative analog library synthesis approach was employed in the exploration of a quinolone carboxylic acid series of selective M(1) positive allosteric modulators, and strategies for improving potency and plasma free fraction were identified.

Synthesis and structure–activity relationships of a series of 3-aryl-4-isoxazolecarboxamides as a new class of TGR5 agonists

A series of 3-aryl-4-isoxazolecarboxamides identified from a high-throughput screening campaign as novel, potent agonists of the human TGR5 G-protein-coupled receptor is described. Many analogues were readily accessible via solution-phase synthesis which resulted in the rapid identification of key structure-activity relationships (SAR), and the discovery of potent exemplars (up to pEC50=9). Details of the SAR and optimization of this series are presented herein.

The synthesis and preclinical evaluation in rhesus monkey of [18F]MK-6577 and [11C]CMPyPB glycine transporter 1 positron emission tomography radiotracers

Two positron emission tomography radiotracers for the glycine transporter 1 (GlyT1) are reported here. Each radiotracer is a propylsulfonamide‐containing benzamide and was labeled with either carbon‐11 or fluorine‐18. [11C]CMPyPB was synthesized by the alkylation of a 3‐hydroxypyridine precursor using [11C]MeI, and [18F]MK‐6577 was synthesized by a nucleophilic aromatic substitution reaction using a 2‐chloropyridine precursor. Each tracer shows good uptake into rhesus monkey brain with the expected distribution of highest uptake in the pons, thalamus, and cerebellum and lower uptake in the striatum and gray matter of the frontal cortex. In vivo blockade and chase studies of [18F]MK‐6577 showed a large specific signal and reversible binding. In vitro autoradiographic studies with [18F]MK‐6577 showed a large specific signal in both rhesus monkey and human brain slices and a distribution consistent with the in vivo results and those reported in the literature. In vivo metabolism studies in rhesus monkeys demonstrated that only more‐polar metabolites are formed for each tracer. Of these two tracers, [18F]MK‐6577 was more extensively characterized and is a promising clinical positron emission tomography tracer for imaging GlyT1 and for measuring GlyT1 occupancy of therapeutic compounds. Synapse, 2011.

Microwave-initiated living free radical polymerization: rapid formation of custom Rasta resins

Abstract Microwave heating of high-loading TEMPO-methyl resin with functionalized styrenyl monomers in a SmithSynthesizer™ affords larger resin beads (>500 μm) via living free radical polymerization. Novel, high-loading Rasta resins (>5.5 mmol/g) are obtained ∼150 times faster than with conventional heating.