Discovery and Lead-Optimization of 4,5-Dihydropyrazoles as Mono-Kinase Selective, Orally Bioavailable and Efficacious Inhibitors of Receptor Interacting Protein 1 (RIP1) Kinase.

RIP1 kinase regulates necroptosis and inflammation and may play an important role in contributing to a variety of human pathologies, including inflammatory and neurological diseases. Currently, RIP1 kinase inhibitors have advanced into early clinical trials for evaluation in inflammatory diseases such as psoriasis, rheumatoid arthritis, and ulcerative colitis and neurological diseases such as amyotrophic lateral sclerosis and Alzheimer's disease. In this paper, we report on the design of potent and highly selective dihydropyrazole (DHP) RIP1 kinase inhibitors starting from a high-throughput screen and the lead-optimization of this series from a lead with minimal rat oral exposure to the identification of dihydropyrazole 77 with good pharmacokinetic profiles in multiple species. Additionally, we identified a potent murine RIP1 kinase inhibitor 76 as a valuable in vivo tool molecule suitable for evaluating the role of RIP1 kinase in chronic models of disease. DHP 76 showed efficacy in mouse models of both multiple sclerosis and human retinitis pigmentosa.

Pharmacological properties of acid N-thiazolylamide FFA2 agonists.

FFA2 is a receptor for short-chain fatty acids. Propionate (C3) and 4-chloro-α-(1-methylethyl)-N-2-thiazolyl-benzeneacetamide (4-CMTB), the prototypical synthetic FFA2 agonist, evoke calcium mobilization in neutrophils and inhibit lipolysis in adipocytes via this G-protein-coupled receptor. 4-CMTB contains an N-thiazolylamide motif but no acid group, and 4-CMTB and C3 bind to different sites on FFA2 and show allosteric cooperativity. Recently, FFA2 agonists have been described that contain both N-thiazolylamide and carboxylate groups, reminiscent of bitopic ligands. These are thought to engage the carboxylate-binding site on FFA2, but preliminary evidence suggests they do not bind to the same site as 4-CMTB even though both contain N-thiazolylamide. Here, we describe the characterization of four FFA2 ligands containing both N-thiazolylamide and carboxylate. (R)-3-benzyl-4-((4-(2-chlorophenyl)thiazol-2-yl)(methyl)amino)-4-oxobutanoic acid (compound 14) exhibits allosteric agonism with 4-CMTB but not C3. Three other compounds agonize FFA2 in [(35)S]GTPγS-incorporation or cAMP assays but behave as inverse agonists in yeast-based gene-reporter assays, showing orthosteric antagonism of C3 responses but allosteric antagonism of 4-CMTB responses. Thus, the bitopic-like FFA2 ligands engage the orthosteric site but do not compete at the site of 4-CMTB binding on an FFA2 receptor molecule. Compound 14 activates FFA2 on human neutrophils and mouse adipocytes, but appears not to inhibit lipolysis upon treatment of human primary adipocytes in spite of the presence of a functional FFA2 receptor in these cells. Hence, these new ligands may reveal differences in coupling of FFA2 between human and rodent adipose tissues.

Discovery of novel indazole derivatives as dual angiotensin II antagonists and partial PPARγ agonists.

Identification of indazole derivatives acting as dual angiotensin II type 1 (AT1) receptor antagonists and partial peroxisome proliferator-activated receptor-γ (PPARγ) agonists is described. Starting from Telmisartan, we previously described that indole derivatives were very potent partial PPARγ agonists with loss of AT1 receptor antagonist activity. Design, synthesis and evaluation of new central scaffolds led us to the discovery of pyrrazolopyridine then indazole derivatives provided novel series possessing the desired dual activity. Among the new compounds, 38 was identified as a potent AT1 receptor antagonist (IC50=0.006 µM) and partial PPARγ agonist (EC50=0.25 µM, 40% max) with good oral bioavailability in rat. The dual pharmacology of compound 38 was demonstrated in two preclinical models of hypertension (SHR) and insulin resistance (Zucker fa/fa rat).

Synthesis and biological activities of novel indole derivatives as potent and selective PPARgamma modulators.

Starting from the structure of Telmisartan, a new series of potent and selective PPARgamma modulators was identified. The synthesis, in vitro and in vivo evaluation of the most potent compounds are reported and the X-ray structure of compound 7b bound to the PPARgamma ligand binding domain is described.

The discovery of equipotent PPARalpha/gamma dual activators.

We report the design and synthesis of equipotent PPARalpha/gamma dual agonists starting from selective PPAR alpha agonist 1. In vivo data for 7 in the Zucker fa/fa rat are presented.

Design, synthesis and evaluation of trifluoromethane sulfonamide derivatives as new potent and selective peroxisome proliferator-activated receptor alpha agonists.

Starting from the structure of 5, a two-step strategy was applied to identify a new generation of trifluoromethane sulfonamides as potent PPARalpha agonists. Synthesis, in vitro and in vivo evaluation of the most potent compound are reported.

An isosparteine derivative for stereochemical assignment of stereogenic (chiral) methyl groups using tritium NMR: theory and experiment.

(N-CHDT)-(alpha)-isosparteinium ditosylamide can be used in conjunction with tritium NMR spectroscopy to assign the configuration of an intact stereogenic (chiral) methyl group. The S-CHDT group has a (3)H chemical shift that is 49 ppb downfield of the R-CHDT resonance. The sign and magnitude of this chemical shift difference of these diastereotopic tritium nuclei are found to be in agreement with predictions made via a purely ab initio computational approach. The chemical shift difference is due to an equilibrium isotope effect originating from a novel CH(3)(...)N hydrogen bond. Despite the improved tritium chemical shift dispersion, this method is not useful for determining the enantiopurity of CHDTN(Tos)(2) due to partial racemization that occurs during the derivatization step. Milder methylation conditions are described for reactions using methyl p-toluenesulfonate or methyl-d(3) triflate. These studies suggest that (-)-(alpha)-isosparteine is a potential new reagent for chirality analysis of methyl groups originating from suitably reactive electrophiles.

Synthesis and DNA binding properties of saturated distamycin analogues.

A series of saturated heterocyclic analogues of distamycin were prepared and examined. A fluorescent intercalator displacement (FID) assay conducted on p[dA]-p[dT] DNA to obtain C(50) values and a hairpin deoxyoligonucleotide containing an A/T-rich binding site was used to evaluate DNA binding affinity. It is observed that saturated heterocycles greatly reduce the DNA binding relative to distamycin.

Highly chemoselective hydrogenolysis of iodoarenes.

The catalytic hydrodehalogenation reaction using molecular hydrogen and Pd/C has been revisited. It is shown that the speed of removal of halogen increases with increasing electronegativity I < Br < Cl. Nevertheless, selective dehydrohalogenation in compounds containing other reducible functions can be achieved only with iodine and not with bromine or chlorine. Selective deiodination of iodobenzophenone could be accomplished without reducing the carbonyl group. Hydrogenolysis of azidoiodoaromatic compounds to the corresponding azido compounds is high yielding. This selectivity was exploited for the labeling of benzophenone- and azido-containing compounds by deuterium and tritium.