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Abstract: A series of N-fluoroalkyl-8-(6-methoxy-2-methylpyridin-3-yl)-2,7-dimethyl-N-alkylpyrazolo[1,5-a][1,3,5]triazin-4-amines were prepared and evaluated as potential CRF1R PET imaging agents. Optimization of their CRF1R binding potencies and octanol–phosphate buffer phase distribution coefficients resulted in discovery of analog 7e (IC50 =6.5nM, log D =3.5). [Copyright &y& Elsevier]

Abstract: Substituted 1-tosyl-3-vinylindoles undergo [3+2] dipolar cycloaddition with cyclic nitrones to afford substituted isoxazoles in good yield and high diastereoselectivity. The cycloadducts were readily converted in 4 steps into ring constrained homotryptamine analogs. These analogs exhibited excellent binding affinity for the human serotonin transporter (hSERT). Indoles bearing a 5-cyano group and a pendent ethyl(tetrahydroisoquinoline) moiety at the 3-position displayed the best potency for hSERT and high selectivity versus hDAT and hNET. [Copyright &y& Elsevier]

The present studies have identified a series of aminotriazines as novel 5-HT7 receptor antagonists. Compounds 10 and 17 have high affinity for the 5-HT7 receptor and do not bind to either the 5-HT2C or 5-HT6 receptors. These compounds produce no agonist effects by themselves, and shift the dose–response curve of 5-CT to the right in the manner of an antagonist. [Copyright &y& Elsevier]

Optimization of a benzyl piperazine pharmacophore produced N-acyl-4-indanyl-piperazines that bind with high affinity to melatonergic MT2 receptors. (R)-4-(2,3-dihydro-6-methoxy-1H-inden-1-yl)-N-ethyl-1-piperazine-carboxamide fumarate (13) is a water soluble, selective MT2 agonist, which produces advances in circadian phase in rats at doses of 1–56 mg/kg that are no different from those of melatonin at 1 mg/kg. Unlike melatonin, 13 produced only weak contractile effects in rat tail artery. [Copyright &y& Elsevier]

A new 5-HT1A silent antagonist 14 (5-HT1A IC50=2.2 nM) antagonizes the effects of agonists on reciprocal forepaw treading behavior, on neuronal firing in the rat dorsal raphe´, and on 5-HT1A release in the raphe´ and hippocampus. While 14 alone was inactive in the social interaction paradigm, it completely reversed the social interaction activity of the serotonergic compounds (buspirone, 1, and 2). [Copyright &y& Elsevier]

A method is presented for the one-pot synthesis of homotryptamines by the MacMillan reaction of indoles with acrolein followed by reductive amination. [Copyright &y& Elsevier]

Abstract: Based on a favorable balance between CRF-R1 affinity, lipophilicity and metabolic stability, compound 10 was evaluated for potential development as PET radioligand. Compound [18F]10 was prepared with high radiochemical purity and showed promising binding properties in rat brain imaging experiments. [Copyright &y& Elsevier]

A series of chiral heterocyclic aminopyrrolidine derivatives was synthesized as novel melatoninergic ligands. Binding affinity assays were performed on cloned human MT1 and MT2 receptors, stably expressed in NIH3T3 cells. Compound 16 was identified as an orally bioavailable agonist at MT1 and MT2 melatonin receptors with low vasoconstrictive activity. [Copyright &y& Elsevier]

Abstract: Introduction: A radioligand for measuring the density of corticotropin-releasing factor subtype-1 receptors (CRF1 receptors) in living animal and human brain with positron emission tomography (PET) would be a useful tool for neuropsychiatric investigations and the development of drugs intended to interact with this target. This study was aimed at discovery of such a radioligand from a group of CRF1 receptor ligands based on a core 3-(phenylamino)‐pyrazin-2(1H)-one scaffold. Methods: CRF1 receptor ligands were selected for development as possible PET radioligands based on their binding potency at CRF1 receptors (displacement of [125I]CRF from rat cortical membranes), measured lipophilicity, autoradiographic binding profile in rat and rhesus monkey brain sections, rat biodistribution, and suitability for radiolabeling with carbon-11 or fluorine-18. Two identified candidates (BMS-721313 and BMS-732098) were labeled with fluorine-18. A third candidate (BMS-709460) was labeled with carbon-11 and all three radioligands were evaluated in PET experiments in rhesus monkey. CRF1 receptor density (B max) was assessed in rhesus brain cortical and cerebellum membranes with the CRF1 receptor ligand, [3H]BMS-728300. Results: The three ligands selected for development showed high binding affinity (IC 50 values, 0.3–8nM) at CRF1 receptors and moderate lipophilicity (LogD, 2.8–4.4). [3H]BMS-728300 and the two 18F-labeled ligands showed region-specific binding in rat and rhesus monkey brain autoradiography, namely higher binding density in the frontal and limbic cortex, and cerebellum than in thalamus and brainstem. CRF1 receptor B max in rhesus brain was found to be 50–120 fmol/mg protein across cortical regions and cerebellum. PET experiments in rhesus monkey showed that the radioligands [18F]BMS-721313, [18F]BMS-732098 and [11C]BMS-709460 gave acceptably high brain radioactivity uptake but no indication of the specific binding as seen in vitro. Conclusions: Candidate CRF1 receptor PET radioligands were identified but none proved to be effective for imaging monkey brain CRF1 receptors. Higher affinity radioligands are likely required for successful PET imaging of CRF1 receptors. [Copyright &y& Elsevier]

Abstract: A series of pyrazinones were prepared and evaluated as potential CRF1R PET imaging agents. Optimization of their CRF1R binding potencies and octanol–phosphate buffer phase distribution coefficients are discussed herein. [Copyright &y& Elsevier]

Abstract: A series of hybrid molecules containing the cyclopropylmethylamino side chain found in homotryptamine (1S,2S)-2c and an isosteric heteroaryl or naphthyl core were prepared and their binding affinities for the human serotonin transporter determined. The most potent isosteres were CN-substituted naphthalenes. These results demonstrate that isosteric aromatic cores which lack an H-bond donor site may be substituted for the indole nucleus without substantial loss in hSERT binding. [Copyright &y& Elsevier]

Abstract: A series of indole tetrahydropyridine and indole cyclohexenylamines was prepared, and their binding affinities at the human serotonin transporter (SERT) were determined. In particular, a nitrile substituent at the C5 position of the indole ring gave potent SERT activity. The stereochemistry of the N,N-dimethylamine substituent was determined for the most potent indole cyclohexenylamine, 6a. The enantiomers of 6a were energy minimized and compared to other conformationally restricted SSRIs. Compound 6a was found to give a dose–response similar to the SSRI fluoxetine in microdialysis studies in rats. [Copyright &y& Elsevier]

Abstract: BMS-505130 is a potent and selective serotonin transport inhibitor; K i for binding to the serotonin transporter=0.18 nM (K i values for binding to the norepinephrine and dopamine transporters=4.6 and 2.1 μM, respectively). In platelet serotonin uptake studies BMS-505130 (5 mg/kg, p.o.) produced a robust inhibition of serotonin uptake. In microdialysis studies oral dosing with BMS-505130 produced a dose-dependent increase in cortical serotonin levels that reached a maximal effect of 200% above baseline at a dose of 1 mg/kg, p.o.; the peak serotonin response was transient in nature. Following oral administration, peak plasma concentrations of BMS-505130 reached Tmax at 1.6±0.7 h and then declined to concentrations <10% of Cmax within the following 6 h; plasma half-life following i.v. dosing was 0.46±0.02 h. Parallel microdialysis and pharmacokinetic studies revealed that changes in serotonin levels in the cortex mirrored changes in the brain concentration of BMS-505130. In a behavioral assay known to be sensitive to selective serotonin reuptake inhibitors (SSRIs), mouse tail suspension, BMS-505130 produced a robust response after either oral or intraperitoneal dosing. BMS-505130 exhibits a pharmacological, neurochemical and behavioral profile consistent with a potent SSRI. Moreover, BMS-505130''s short half-life may be advantageous for the treatment of premature ejaculation where an acute effect to delay ejaculation followed by a relatively rapid fall in SSRI plasma concentrations might be desirable. [Copyright &y& Elsevier]

The present studies have identified a series of diaminopyrimidines and diaminopyridines as novel 5-HT7 receptor ligands. Three regiosiomeric classes of pyrimidines and four regioisomeric classes of pyridines were synthesized and analyzed for binding to the 5-HT7 receptor. The 5-HT7 binding affinities of different regioisomers show clearly the structure–activity relationship with position of ring nitrogens. [Copyright &y& Elsevier]

Abstract: Racemic 5-(trans-2-aminomethylcyclopropyl)indoles, 5-(trans-2-aminomethylcyclopentyl) indoles, and 5-(cis-2-aminomethylcyclopentyl)indoles were synthesized and evaluated as selective serotonin reuptake inhibitors. These analogs followed SAR trends similar to those previously reported for 3-cycloalkyl substituted indoles. The most potent analogs exhibited single digit nanomolar inhibition at the human serotonin transporter but were 10-fold less active than the previously reported compounds. [Copyright &y& Elsevier]

Abstract: A series of racemic 3-(trans-2-aminomethylcyclopentyl)indoles was synthesized and found to have potent binding to the human serotonin transporter (hSERT). The most active analog was synthesized stereospecifically and the active enantiomer was shown to have high affinity binding to hSERT. [Copyright &y& Elsevier]

Abstract: A series of N,N-dimethylhomotryptamines was prepared and their binding affinities at the serotonin transporter (SERT) were determined. Compounds possessing an electron withdrawing substituent at the C5-position of the indole nucleus were found to be potent SSRIs. Initial attempts at conformational restriction of the propylamine sidechain by incorporation of a quinuclidine bicyclic structure did not improve binding affinity at SERT. [Copyright &y& Elsevier]