Synergistic inhibition of Aβ production by combinations of γ-secretase modulators.

Alzheimer's disease is associated with the accumulation of amyloid-β (Aβ) in the brain. In particular, the 42-amino acid form, Aβ1-42, is thought to play a key role in the disease. It is therefore of interest that diverse compounds, known as γ-secretase modulators (GSM), can selectively decrease Aβ1-42 production without inhibiting the production of other forms of Aβ.

Identification and Preclinical Pharmacology of the γ-Secretase Modulator BMS-869780.

Alzheimer's disease is the most prevalent cause of dementia and is associated with accumulation of amyloid-β peptide (Aβ), particularly the 42-amino acid Aβ1-42, in the brain. Aβ1-42 levels can be decreased by γ-secretase modulators (GSM), which are small molecules that modulate γ-secretase, an enzyme essential for Aβ production. BMS-869780 is a potent GSM that decreased Aβ1-42 and Aβ1-40 and increased Aβ1-37 and Aβ1-38, without inhibiting overall levels of Aβ peptides or other APP processing intermediates.

Heterocyclic modification of a novel bicyclo[3.1.0]hexane NPY1 receptor antagonist.

A convergent synthesis route for the heterocyclic modification of a novel bicyclo[3.1.0]hexane NPY1 antagonist 2 was developed and the structure activity relationship of these modifications on NPY1 binding is reported.

Acyl guanidine inhibitors of β-secretase (BACE-1): optimization of a micromolar hit to a nanomolar lead via iterative solid- and solution-phase library synthesis.

This report describes the discovery and optimization of a BACE-1 inhibitor series containing an unusual acyl guanidine chemotype that was originally synthesized as part of a 6041-membered solid-phase library. The synthesis of multiple follow-up solid- and solution-phase libraries facilitated the optimization of the original micromolar hit into a single-digit nanomolar BACE-1 inhibitor in both radioligand binding and cell-based functional assay formats. The X-ray structure of representative inhibitors bound to BACE-1 revealed a number of key ligand:protein interactions, including a hydrogen bond between the side chain amide of flap residue Gln73 and the acyl guanidine carbonyl group, and a cation-π interaction between Arg235 and the isothiazole 4-methoxyphenyl substituent.

Discovery of a Novel Class of Bicyclo[3.1.0]hexanylpiperazines as Noncompetitive Neuropeptide Y Y1 Antagonists.

A novel class of bicyclo[3.1.0]hexanylpiperazine neuropeptide Y (NPY) Y1 antagonists has been designed and synthesized.

[3H]BMS-599240--a novel tritiated ligand for the characterization of BACE1 inhibitors.

In this report we describe a novel radioligand, [(3)H](S)-2-((S)-3-Acetylamino-3-sec-butyl-2-oxo-pyrrolidin-1-yl)-N-[(1S,2R)-1-benzyl-2-hydroxy-3-(3-methoxy-benzylamino)-propyl]-4-phenyl-butyramide ([(3)H]BMS-599240), that exhibits robust specific binding in homogenates from cell cultures overexpressing beta-site amyloid precursor protein cleaving enzyme-1 (BACE1). Radioligand binding exhibited high affinity, K(d)=2 nM, commensurate with its inhibitory potency against BACE1. Inhibition of radioligand binding in the presence of a range of different BACE1 inhibitors exhibited the same rank order of potency as for inhibition of BACE1 enzymatic activity.

The amyloid-beta rise and gamma-secretase inhibitor potency depend on the level of substrate expression.

The amyloid-beta (Abeta) peptide, which likely plays a key role in Alzheimer disease, is derived from the amyloid-beta precursor protein (APP) through consecutive proteolytic cleavages by beta-site APP-cleaving enzyme and gamma-secretase. Unexpectedly gamma-secretase inhibitors can increase the secretion of Abeta peptides under some circumstances. This "Abeta rise" phenomenon, the same inhibitor causing an increase in Abeta at low concentrations but inhibition at higher concentrations, has been widely observed.

Pharmacological characterization and appetite suppressive properties of BMS-193885, a novel and selective neuropeptide Y(1) receptor antagonist.

Treatment of obesity is still a large unmet medical need. Neuropeptide Y is the most potent orexigenic peptide in the animal kingdom. Its five cloned G-protein couple receptors are all implicated in the regulation of energy homeostasis evidenced by overexpression or deletion of neuropeptide Y or its receptors.

Signal peptide peptidase and gamma-secretase share equivalent inhibitor binding pharmacology.

The enzyme gamma-secretase has long been considered a potential pharmaceutical target for Alzheimer disease. Presenilin (the catalytic subunit of gamma-secretase) and signal peptide peptidase (SPP) are related transmembrane aspartyl proteases that cleave transmembrane substrates. SPP and gamma-secretase are pharmacologically similar in that they are targeted by many of the same small molecules, including transition state analogs, non-transition state inhibitors, and amyloid beta-peptide modulators.

Synthesis and evaluation of 5,5-diphenylimidazolones as potent human neuropeptide Y5 receptor antagonists.

A series of novel 5,5-diphenylimidazolones was synthesized and evaluated for activity against the human neuropeptide Y5 receptor. The 3-pyridyl analog 46 demonstrated an IC(50) of 8.3 nM with a favorable pharmacokinetic profile in rats, but was ineffective in reducing food intake.

4-Substituted anilides as selective melatonin MT2 receptor agonists.

A series of 4-substituted anilides with human melatonergic affinity is reported. Butyramides 26, 39, 42, 52, 57, and 58 all demonstrated subnanomolar MT(2) binding affinity and MT(2) selectivity of at least 70-fold over the MT(1) receptor. Compound 26 demonstrated full agonism at the MT(2) receptor.

Differentially functionalized diamines as novel ligands for the NPY2 receptor.

The synthesis of novel ligands for the NPY(2) receptor using solid phase split pool methodology is described. One of the analogues, diamine 16, was found to be a potent NPY(2) binder.

Dihydropyridine neuropeptide Y Y(1) receptor antagonists.

Dihydropyridine 5a was found to be an inhibitor of neuropeptide Y(1) binding in a high throughput (125)I-PYY screening assay. Structure-activity studies around certain portions of the dihydropyridine chemotype identified BMS-193885 (6e) as a potent and selective Y(1) receptor antagonist. In a forskolin-stimulated c-AMP production assay using CHO cells expressing the human Y(1) receptor, 6e demonstrated full functional antagonism (K(b)=4.

Structural organization and chromosomal localization of three human galanin receptor genes.

Human galanin receptor subtypes GALR1, GALR2, and GALR3 are encoded by separate genes that are located on human chromosomes 18q23, 17q25.3, and 22q13.1, respectively.

Molecular characterization, pharmacological properties and chromosomal localization of the human GALR2 galanin receptor.

The neuropeptide galanin mediates a diverse spectrum of biological activities by interacting with specific G protein-coupled receptors. We have used homology genomic library screening and polymerase chain reaction (PCR) techniques to isolate both genomic and cDNA clones encoding the human homolog of the recently cloned rat GALR2 galanin receptor. By fluorescence in situ hybridization, the gene encoding human GALR2 (GALNR2) has been localized to chromosome 17q25.

Cloning, pharmacological characterization and distribution of a novel galanin receptor.

The neuropeptide galanin mediates a diverse spectrum of biological activities by interacting with specific G-protein-coupled receptors. Through expression cloning, human and rat GALR1 receptor cDNA clones have previously been isolated and characterized. In this study, we have used homology screening to isolate a rat brain cDNA clone encoding a second galanin receptor subtype, the GALR2 receptor.

Cloning and characterization of the rat GALR1 galanin receptor from Rin14B insulinoma cells.

Galanin is a ubiquitous neuropeptide that regulates a wide array of physiological processes via interaction with specific G protein-coupled receptors. A rat galanin receptor cDNA was cloned from the Rin14B insulinoma cell line. The isolated cDNA encodes a 346 amino acid G protein-coupled receptor that is 92% identical to the recently reported human GALR1 galanin receptor.

Cloning, expression, and tissue distribution of a fifth melanocortin receptor subtype.

The melanocortin (MC) peptides mediate a diverse spectrum of biological activities in both the central nervous system and peripheral tissues by interacting with specific guanine nucleotide binding (G protein)-coupled receptors. Previously, four human melanocortin receptor subtypes have been cloned and characterized. In this study, we have isolated mouse complementary DNA (cDNA) and human genomic clones encoding a fifth melanocortin receptor subtype, MC5.

Differential sensitivity of 3H-agonist binding to pre- and postsynaptic 5-HT1A receptors in bovine brain.

1. The full and weak partial 5-HT1A agonist ligands [3H]-8-OH-DPAT and [3H]-BMY-7378 were used to characterize the binding parameters of pre- and postsynaptic 5-HT1A binding sites in bovine dorsal raphe and hippocampal membranes, respectively. The Kd and Bmax values for the individual radioligands were indistinguisable across the regions tested, as were the Ki values generated by a series of agents acting at 5-hydroxytryptamine (5-HT) receptors.

Characterization of human 5-HT1 receptors expressed in Sf9 insect cells.

Four human 5-HT receptor subtypes (5-HT1A, 5-HT1D alpha, 5-HT1D beta and 5-HT1E) have been expressed in Sf9 insect cells. All four human 5-hydroxytryptamine receptors produced by Sf9 cells had the expected pharmacological properties. Surprisingly, levels of expression of these receptors were relatively low (1-5 pmol/mg protein).

A single amino acid difference accounts for the pharmacological distinctions between the rat and human 5-hydroxytryptamine1B receptors.

Molecular cloning of the rat and human 5-hydroxytryptamine1B (5-HT1B) receptors has revealed that the primary amino acid sequence of these two receptors is > 90% identical. Despite this high degree of primary sequence homology, these two receptors have significantly different pharmacological properties. A mutant human 5-HT1B receptor was constructed in which Thr355 was replaced by Asn, the corresponding residue at this position in the rat 5-HT1B receptor.

Effect of encainide, ODE, MODE, and flecainide on ADP/5-HT induced platelet aggregation and in the anesthetized dog coronary artery stenosis-occlusion model of intravascular thrombosis.

Encainide is a class 1C antiarrhythmic agent that is indicated for the treatment of life-threatening arrhythmias, such as sustained ventricular tachycardia. Furthermore, encainide possesses a moderate degree of antiserotonin activity, which was quantitated in this present study by determining displacement of [3H]spiperone binding from rat cortical 5-HT2 binding sites. The Ki for encainide in this model was 66.