1-Benzyloxy-4,5-dihydro-1H-imidazol-2-yl-amines,a novel class of NR1/2B subtype selective NMDA receptor antagonists

Screening of the Roche compound depository led to the identification of (1-benzyloxy-4,5-dihydro-1H-imidazol-2-yl)-butyl amine 4, a structurally novel NR1/2B subtype selective NMDA receptor antagonist. The structure-activity relationships developed in this series resulted in the discovery of a novel class of potent and selective NMDA receptor blockers displaying activity in vivo.     

4-Aminoquinolines as a novel class of NR1/2B subtype selective NMDA receptor antagonists

Screening of the Roche compound library led to the identification of 4-aminoquinoline 4 as structurally novel NR1/2B subtype selective NMDA receptor antagonist. The SAR which was developed in this series resulted in the discovery of highly potent and in vivo active blockers.     

1,3-diaminopropan-2-ol sulfonamides as potent and selective inhibitors of the glycine transporter type 1

High throughput screening led to the discovery of a novel series of 1,3-diaminopropan-2-ol sulfonamides as selective GlyT-1 inhibitors. Structure-activity relationships of this novel series and optimisation of the initial hit that led to the identification of (2), a potent and selective GlyT-1 inhibitor, are also presented.     

超极化激活的环核苷酸门控通道（HCN 通道）抑制剂的研究进展

超极化激活的环核苷酸门控通道(HCN通道)有四个亚型,分别为HCN1-4。HCN通道各亚型之间的基本结构相似,在许多组织中均有表达,其中以大脑和心脏组织中表达最为丰富。HCN通道既参与所在组织的正常生理功能,也与所在组织的病理状态密切相关。如神经损伤引起的神经源性疼痛常检测到HCN1通道表达量的增加,肥厚性心肌病和终末期心力衰竭等病理状态下常检测到心室肌细胞HCN4 mRNA及HCN2 mRNA表达增加。鉴于HCN通道与许多疾病密切相关,因此,以其为靶点来治疗相关疾病成为可能,但是由于HCN通道分布广泛,而目前该通道阻滞剂均为非选择性亚型抑制剂,临床应用时不可避免的引起副反应,因此发展选择性HCN通道亚型抑制剂就显得刻不容缓。本文就HCN通道抑制剂的研究发展做进一步探讨。     

3D pharmacophore based virtual screening of T-type calcium channel blockers

Virtual screening of the commercial databases was done by using a three dimensional pharmacophore previously developed for T-type calcium channel blockers using CATALYSTtrade mark program. Biological evaluation of 25 selected virtual hits resulted in the discovery of a highly potent compound VH04 with IC(50) value of 0.10 microM, eight times as potent as the known selective T-type calcium channel blocker, mibefradil. Search for similar compounds yielded several hits with micro-molar IC(50) values and high T-type calcium channel selectivity. Based on the structure of the virtual hits, small molecule libraries with novel scaffolds were designed, synthesis and biological evaluation of which are currently in progress. This result shows a successful example of ligand based drug discovery of potent T-type calcium channel blockers.     

Structure-activity relationship (SAR) investigations of substituted imidazole analogs as TRPV1 antagonists

A novel series of 4,5-biarylimidazoles as TRPV1 antagonists were designed based on the previously reported 4,6-disubstituted benzimidazole series. The analogs were evaluated for their ability to block capsaicin- or acid-induced calcium influx in TRPV1-expressing CHO cells. These studies led to the identification of a highly potent and orally bioavailable TRPV1 antagonist, imidazole 33.     

Discovery of potent,selective and orally bioavailable imidazo[1,5-a]pyrazine derived ACK1 inhibitors

This Letter describes the medicinal chemistry effort towards a series of novel imidazo[1,5-a]pyrazine derived inhibitors of ACK1. Virtual screening led to the discovery of the initial hit, and subsequent exploration of structure–activity relationships and optimization of drug metabolism and pharmacokinetic properties led to the identification of potent, selective and orally bioavailable ACK1 inhibitors.     

Discovery of benzophosphadiazine drug candidate IDX375: A novel hepatitis C allosteric NS5B RdRp inhibitor

Hepatitis C virus (HCV) NS5B RNA-dependent RNA polymerase (RdRp) plays a central role in virus replication. NS5B has no functional equivalent in mammalian cells, and as a consequence is an attractive target for selective inhibition. This paper describes the discovery of a novel family of HCV NS5B non-nucleoside inhibitors inspired by the bioisosterism between sulfonamide and phosphonamide. Systematic structural optimization in this new series led to the identification of IDX375, a potent non-nucleoside inhibitor that is selective for genotypes 1a and 1b. The structure and binding domain of IDX375 were confirmed by X-ray co-crystalisation study.     

Discovery of potent and use-dependent sodium channel blockers for treatment of chronic pain

A new series of voltage-gated sodium channel blockers with potential for treatment of chronic pain is reported. Systematic structure-activity relationship studies, starting with compound 1, led to identification of potent analogs that displayed use-dependent block of sodium channels, were efficacious in pain models in vivo, and most importantly, were devoid of activity against the cardiac potassium channel hERG.     

Novel, druglike 1,7-disubstituted 2,3,4,5-tetrahydro-1H-benzo[b]azepine-based selective inhibitors of human neuronal nitric oxide synthase (nNOS)

A novel class of 1,7-disubstituted 2,3,4,5-tetrahydro-1H-benzo[b]azepine derivatives was designed, synthesized and evaluated as human nitric oxide synthase (NOS) inhibitors. Structure-activity relationship studies based on various basic amine side chains attached at the 1-position of the 2,3,4,5-tetrahydro-1H-benzo[b]azepine ring led to the identification of several potent and highly selective inhibitors (17, 18, 25, (±)-39, and (±)-40) of human neuronal NOS. The potential therapeutic application of one of these new selective nNOS inhibitors (17) was demonstrated in an in vivo spinal nerve ligation model of neuropathic pain, and various in vitro safety pharmacology studies such as the hERG K(+) channel inhibition assay and high throughput broad screen (minimal activity at 79 receptors/transporters/ion channels).     

The discovery and optimization of benzimidazoles as selective NaV1.8 blockers for the treatment of pain

The voltage gated sodium channel Na_V1.8 has been postulated to play a key role in the transmission of pain signals. Core hopping from our previously reported phenylimidazole leads has allowed the identification of a novel series of benzimidazole Na_V1.8 blockers. Subsequent optimization allowed the identification of compound 9, PF-06305591, as a potent, highly selective blocker with an excellent preclinical in vitro ADME and safety profile.     

Discovery of N-(2-aryl-cyclohexyl) substituted spiropiperidines as a novel class of GlyT1 inhibitors

Screening of the Roche compound library led to the identification of cis-N-(2-phenyl-cyclohexyl)-spiropiperidine 1 as structurally novel GlyT1 inhibitor. The SAR, which was developed in this series, resulted in the discovery of highly potent compounds displaying excellent selectivity against the GlyT2 isoform.     

Characterization of a new class of potent inhibitors of the voltage-gated sodium channel Nav1.7

Voltage-gated sodium channels (Nav1) transmit pain signals from peripheral nociceptive neurons, and blockers of these channels have been shown to ameliorate a number of pain conditions. Because these drugs can have adverse effects that limit their efficacy, more potent and selective Nav1 inhibitors are being pursued. Recent human genetic data have provided strong evidence for the involvement of the peripheral nerve sodium channel subtype, Nav1.7, in the signaling of nociceptive information, highlighting the importance of identifying selective Nav1.7 blockers for the treatment of chronic pain. Using a high-throughput functional assay, novel Nav1.7 blockers, namely, the 1-benzazepin-2-one series, have recently been identified. Further characterization of these agents indicates that, in addition to high-affinity inhibition of Nav1.7 channels, selectivity against the Nav1.5 and Nav1.8 subtypes can also be achieved within this structural class. The most potent, nonselective member of this class of Nav1.7 blockers has been radiolabeled with tritium. [3H]BNZA binds with high affinity to rat brain synaptosomal membranes (Kd = 1.5 nM) and to membranes prepared from HEK293 cells stably transfected with hNav1.5 (Kd = 0.97 nM). In addition, and for the first time, high-affinity binding of a radioligand to hNav1.7 channels (Kd = 1.6 nM) was achieved with [3H]BNZA, providing an additional means for identifying selective Nav1.7 channel inhibitors. Taken together, these data suggest that members of the novel 1-benzazepin-2-one structural class of Nav1 blockers can display selectivity toward the peripheral nerve Nav1.7 channel subtype, and with appropriate pharmacokinetic and drug metabolism properties, these compounds could be developed as analgesic agents.     

2-(Aminomethyl)-benzamide-based glycine transporter type-2 inhibitors

Structure-activity studies on benzamide 1 obtained from library screening led to the discovery of a novel series of potent and selective glycine transporter type-2 inhibitors.     

Structure-activity study and analgesic efficacy of amino acid derivatives as N-type calcium channel blockers

The synthesis and structure-activity relationship (SAR) study of a novel series of N-type calcium channel blockers are described. L-Cysteine derivative 2a was found to be a potent and selective N-type calcium channel blocker with IC(50) 0.63 microM on IMR-32 assay. Compound 2a showed analgesic efficacy in the rat formalin-induced pain model by intrathecal and oral administration.     

Oxazolidinones as novel human CCR8 antagonists

High-throughput screening of the corporate compound collection led to the discovery of a novel series of N-substituted-5-aryl-oxazolidinones as potent human CCR8 antagonists. The synthesis, structure-activity relationships, and optimization of the series that led to the identification of SB-649701 (1a), are described.     

The discovery of potent and selective pyridopyrimidin-7-one based inhibitors of B-RafV600E kinase

Herein we describe the discovery of a novel series of ATP competitive B-Raf inhibitors via structure based drug design (SBDD). These pyridopyrimidin-7-one based inhibitors exhibit both excellent cellular potency and striking B-Raf selectivity. Optimization led to the identification of compound 17, a potent, selective and orally available agent with excellent pharmacokinetic properties and robust tumor growth inhibition in xenograft studies.     

Synthesis and SAR studies of a novel series of T-type calcium channel blockers

For the novel, potent, and selective T-type Ca2+ channel blockers, a series of sulfonamido-containing 3,4-dihydroquinazoline derivatives were prepared and evaluated for their blocking actions on T- and N-type Ca2+ channels. Among them, 9c (KYS05064, IC50 = 0.96 +/- 0.22 microM) was found to be as potent as Mibefradil and also showed the highest selectivity for T-type Ca2+ channel with no effect on N-type Ca2+ channel.     

Salt bridges and gating in the COOH-terminal region of HCN2 and CNGA1 channels

Hyperpolarization-activated cyclic nucleotide-modulated (HCN) channels and cyclic nucleotide-gated (CNG) channels are activated by the direct binding of cyclic nucleotides. The intracellular COOH-terminal regions exhibit high sequence similarity in all HCN and CNG channels. This region contains the cyclic nucleotide-binding domain (CNBD) and the C-linker region, which connects the CNBD to the pore. Recently, the structure of the HCN2 COOH-terminal region was solved and shown to contain intersubunit interactions between C-linker regions. To explore the role of these intersubunit interactions in intact channels, we studied two salt bridges in the C-linker region: an intersubunit interaction between C-linkers of neighboring subunits, and an intrasubunit interaction between the C-linker and its CNBD. We show that breaking these salt bridges in both HCN2 and CNGA1 channels through mutation causes an increase in the favorability of channel opening. The wild-type behavior of both HCN2 and CNGA1 channels is rescued by switching the position of the positive and negative residues, thus restoring the salt bridges. These results suggest that the salt bridges seen in the HCN2 COOH-terminal crystal structure are also present in the intact HCN2 channel. Furthermore, the similar effects of the mutations on HCN2 and CNGA1 channels suggest that these salt bridge interactions are also present in the intact CNGA1 channel. As disrupting the interactions leads to channels with more favorable opening transitions, the salt bridges appear to stabilize a closed conformation in both the HCN2 and CNGA1 channels. These results suggest that the HCN2 COOH-terminal crystal structure contains the C-linker regions in the resting configuration even though the CNBD is ligand bound, and channel opening involves a rearrangement of the C-linkers and, thus, disruption of the salt bridges. Discovering that one portion of the COOH terminus, the CNBD, can be in the activated configuration while the other portion, the C-linker, is not activated has lead us to suggest a novel modular gating scheme for HCN and CNG channels.     

Discovery and optimization of a novel series of pyrazolyltetrahydropyran N-type calcium channel (Cav 2.2) blockers for the treatment of pain

A novel series of pyrazolyltetrahydropyran N-type calcium channel blockers are described. Structural modifications of the series led to potent compounds in both a cell-based fluorescent calcium influx assay and a patch clamp electrophysiology assay. Representative compounds from the series were bioavailable and showed efficacy in the rat CFA and CCI models of inflammatory and neuropathic pain.