Novel imidazole-based histamine H3 antagonists.

A novel series of imidazole containing histamine H(3) receptor ligands were investigated and found to be potent functional antagonists. After improving the stability of these molecules towards liver microsomes, these compounds were found to have no appreciable affinity for CYP P450s. Subsequent in vivo experiments showed significant brain uptake of (4-chloro-phenyl)-[2-(1-isopropyl-piperidin-4-ylmethoxy)-3-methyl-3H-imidazol-4-yl]-methanone 22.

2-Aryloxymethylmorpholine histamine H(3) antagonists.

The synthesis and biological activity of a new series of 2-aryloxymethylmorpholine histamine H(3) antagonists is described. The new compounds are high affinity histamine H(3) ligands that penetrate the CNS and occupy the histamine H(3) receptor in rat brain.

Effects of SB-269970, a 5-HT7 receptor antagonist, in mouse models predictive of antipsychotic-like activity.

5-HT7 receptors have been linked to a number of psychiatric disorders including anxiety and depression. The localization of 5-HT7 receptors in the thalamus, a key sensory processing center, and the high affinity of many atypical antipsychotic compounds for these receptors have led to the speculation of the utility of 5-HT7 antagonists in schizophrenia. The goal of these studies was to examine the effects of pharmacologic blockade and genetic ablation of 5-HT7 receptors in animal models predictive of antipsychotic-like activity. We evaluated the effects of SB-269970, a selective 5-HT7 receptor antagonist, on amphetamine and ketamine-induced hyperactivity and prepulse inhibition (PPI) deficits. In addition, sensorimotor gating function and locomotor activity were evaluated in 5-HT7 knockout mice. Locomotor activity was measured for up to 180 min using an automated infrared photobeam system, and PPI was evaluated in startle chambers. SB-269970 (3, 10 and 30 mg/kg, intraperitoneally) significantly blocked amphetamine [3 mg/kg, subcutaneously (s.c.)] and ketamine (30 mg/kg, s.c.)-induced hyperactivity and reversed amphetamine (10 mg/kg, s.c.)-induced but not ketamine (30 mg/kg, s.c.)-induced PPI deficits, without changing spontaneous locomotor activity and startle amplitude. The largest dose of SB-269970 did not block the effects of amphetamine in 5-HT7 knockout mice. Collectively, these results indicate that blockade of 5-HT7 receptors partially modulates glutamatergic and dopaminergic function and could be clinically useful for the treatment of positive symptoms of schizophrenia.

Lead identification of acetylcholinesterase inhibitors-histamine H3 receptor antagonists from molecular modeling.

Currently, the only clinically effective treatment for Alzheimer's disease (AD) is the use of acetylcholinesterase (AChE) inhibitors. These inhibitors have limited efficacy in that they only treat the symptoms and not the disease itself. Additionally, they often have unpleasant side effects. Here we consider the viability of a single molecule having the actions of both an AChE inhibitor and histamine H(3) receptor antagonist. Both histamine H(3) receptor antagonists and AChE inhibitors improve and augment cholinergic neurotransmission in the cortex. However, whereas an AChE inhibitor will impart its effect everywhere, a histamine H(3) antagonist will raise acetylcholine levels mostly in the brain as its mode of action will primarily be on the central nervous system. Therefore, the combination of both activities in a single molecule could be advantageous. Indeed, studies suggest an appropriate dual-acting compound may offer the desired therapeutic effect with fewer unpleasant side effects [CNS Drugs2004, 18, 827]. Further, recent studies(2) indicate the peripheral anionic site (PAS) of AChE interacts with the beta-amyloid (betaA) peptide. Consequently, a molecule capable of disrupting this interaction may have a significant impact on the production of or the aggregation of betaA. This may result in slowing down the progression of the disease rather than only treating the symptoms as current therapies do. Here, we detail how the use of the available crystal structure information, pharmacophore modeling and docking (automated, manual, classical, and QM/MM) lead to the identification of an AChE inhibitor-histamine H(3) receptor antagonist. Further, based on our models we speculate that this dual-acting compound may interact with the PAS. Such a dual-acting compound may be able to affect the pathology of AD in addition to providing symptomatic relief.

2-Alkyl-4-aryl-pyrimidine fused heterocycles as selective 5-HT2A antagonists.

The synthesis and SAR for a novel series of 2-alkyl-4-aryl-tetrahydro-pyrido-pyrimidines and 2-alkyl-4-aryl-tetrahydro-pyrimido-azepines is described. Representative compounds were shown to be subtype selective 5-HT(2A) antagonists. Optimal placement of a basic nitrogen relative to the pyrimidine and the presence of a 4-fluorophenyl group in the pyrimidine 4-position was found to have a profound effect on affinity and selectivity.

Synthesis and biological activity of piperazine and diazepane amides that are histamine H3 antagonists and serotonin reuptake inhibitors.

The synthesis and biological activity of a new series of piperazine and diazepane amides is described. The new compounds are high affinity histamine H3 ligands and serotonin reuptake inhibitors.

Benzylamine histamine H(3) antagonists and serotonin reuptake inhibitors.

The design, synthesis, and in vitro activity of a series of novel 5-ethynyl-2-aryloxybenzylamine-based histamine H(3) ligands that are also serotonin reuptake transporters is described.

Novel tetrahydroisoquinolines are histamine H3 antagonists and serotonin reuptake inhibitors.

A series of novel 4-aryl-1,2,3,4-tetrahydroisoquinoline-based histamine H(3) ligands that also have serotonin reuptake transporter inhibitor activity is described. The synthesis, in vitro biological data, and select pharmacokinetic data for these novel compounds are discussed.