Discovery of orally bioavailable NK1 receptor antagonists

Benzyloxyphenethylpiperazines are a new class of high affinity NK1 receptor antagonists. Oral bioavailability and selectivity can be fine tuned by the nature of the substituents on the basic nitrogen atom. Addition of substituents with a carboxylic acid group led to very selective and orally active NK1 antagonists free of interaction with L-type calcium channels.     

Novel lactam NK1 antagonists with anti-emetic activity

A series of 4,4-disubstituted cyclohexylamine NK(1) antagonists containing a lactam ring is described. The compounds are brain penetrant and activity is demonstrated in a ferret emesis model.     

Cyclobutane derivatives as potent NK1 selective antagonists

A series of novel cyclobutane derivatives as potent and selective NK1 receptor antagonists is described. Several compounds in this series exhibited high in vitro binding affinity (Ki 相似文献   

The design and synthesis of novel NK1/NK2 dual antagonists

Functional probing of the backbone of the Sanofi NK2 antagonist SR 48968 has resulted in the discovery of two new classes of NK1/NK2 dual antagonists: the diamine class and the oxime class. The addition of the amino or the oxime functional group results in the reversal of the stereochemical preference of the NK2 receptor.     

Discovery of novel, orally active dual NK1/NK2 antagonists

Exploration of the SAR around selective NK2 antagonists, SR48968 and ZD7944, led to the discovery that naphth-1-amide analogues provide potent dual NK1 and NK2 antagonists. ZD6021 inhibited binding of [3H]-NKA or [3H]-SP to human NK1 and NK2 receptors, with high-affinity (K(i)=0.12 and 0.62nM, respectively). In functional assays ZD6021 had, at 10(-7)M, in human pulmonary artery pK(B)=8.9 and in human bronchus pK(B)=7.3, for NK1 and NK2, respectively. Oral administration of ZD6021 to guinea pigs dose-dependently attenuated ASMSP induced extravasation of plasma proteins, ED(50)=0.5mg/kg, and NK2 mediated bronchoconstriction, ED(50)=13mg/kg.     

Design and synthesis of potential dual NK1/NK3 receptor antagonists

The tachykinin NK₁ and NK₃ receptors are a novel drug target for schizophrenia in order to treat not only the positive and cognitive symptoms, but also the associated co-morbid depression and sleep disturbances associated with the disease. A novel class of peptidomimetic derivatives based on a versatile phenylglycine central core was synthesized and tested in vitro as dual NK₁/NK₃ receptor antagonists. From this series emerged compounds with good NK₁ receptor affinity, although only modest dual NK₁/NK₃ receptor affinity was observed with one of these analogs.     

Cyclic urea derivatives as potent NK1 selective antagonists

A series of novel five- and six-membered ring urea derivatives have been described as potent and selective NK1 receptor antagonists. Several compounds in this series exhibited good oral activity and brain penetration. Syntheses of these compounds are also described herein.     

NK1 antagonists based on seven membered lactam scaffolds

A new class of high affinity hNK1R antagonists based on seven-membered ring cores has been identified. This series, with relatively simple, compact structures, includes compounds with high affinity, good selectivity, and promising in vivo properties.     

4,4-Disubstituted cyclohexylamine NK(1) receptor antagonists I

A series of novel 4,4-disubstituted cyclohexylamine based NK(1) antagonists is described. The effect of changes to the C(1)-C(4) relative stereochemistry on the cyclohexane ring and replacements for the flexible linker are discussed, leading to the identification of compounds with high affinity and good in vivo duration of action.     

Biphenyl derivatives as novel dual NK(1)/NK(2)-receptor antagonists

In a continuation of our efforts to simplify the structure of our neurokinin antagonists, a series of substituted biphenyl derivatives has been prepared. Several compounds exhibit potent affinities for both the NK(1) receptor (<10nM) and for the NK(2) receptor (<50 nM). Details on the design, synthesis, biological activities, SAR and conformational analysis of this new class of dual NK(1)/NK(2) receptor antagonists are presented.     

4,4-Disubstituted cyclohexylamine NK(1) receptor antagonists II

A series of novel 4,4-disubstituted cyclohexylamines as NK(1) receptor antagonists is described: modifications to the amine moiety retain NK(1) receptor binding affinity whilst disrupting I(Kr) affinity.     

Identification of novel NK1/NK3 dual antagonists for the potential treatment of schizophrenia

During the lead optimization of NK(1)/NK(3) receptor antagonists program, a focused exploration of molecules bearing a lactam moiety was performed. The aim of the investigation was to identify the optimal position of the carbonyl and hydroxy methyl group in the lactam moiety, in order to maximize the in vitro affinity and the level of insurmountable antagonism at both NK(1) and NK(3) receptors. The synthesis and biological evaluation of these novel lactam derivatives, with potent and balanced NK(1)/NK(3) activity, were reported in this paper.     

Preparation of oxime dual NK(1)/NK(2) antagonists with reduced NK(3) affinity

By employing a stereosimplification approach, a thorough SAR exploration of the piperidine region of Sch 206272 was possible through a practical and efficient synthesis of substituted cyclic ureas. This SAR study led to the identification of a benzimidazolinone series of compounds which display single digit nanomolar NK(1)/NK(2) affinity and near micromolar binding for the NK(3) receptor.     

Fused bicyclic pyrrolizinones as new scaffolds for human NK1 antagonists

Previous work on human NK(1) antagonists in which the core of the structure is a substituted pyrrolidine has been disclosed. These compounds showed good binding affinity and functional IP activity, however, many did not exhibit the necessary brain penetration for good in vivo activity. The discovery and preparation of a novel 5,5-fused pyrrolidine core is presented in this paper. This scaffold maintains the excellent binding affinity and functional IP activity of the previously reported compounds, but also exhibits excellent brain penetration as observed in a gerbil foot-tapping assay. The determination of the core structural stereochemistry, which eventually led to the final synthesis of a single active diastereomer, is described.     

Why receptor reserve matters for neurokinin1 (NK1) receptor antagonists

Abstract

The difference in location between the receptor occupancy curve of an agonist and its functional response has been described as receptor reserve. This “reserve” for a specific receptor has been found to differ from tissue to tissue and between agonists acting on the same tissue. Recently, two structurally different neurokinin 1 (NK1) receptor antagonists were taken into human and both were tested as antidepressants and for insomnia. Vestipitant and Casopitant both have high affinity for the human NK1 receptor (pK_i?=?9.4 and 10.2, respectively). In human, at the chosen clinical doses, receptor occupancy was measured in the frontal cortex, at 24 hours post administration, as ～90% for vestipitant (15?mg) and ～100% for casopitant (30?mg). In patients with moderate to severe major depression, vestipitant given at 15?mg for 8 weeks showed no statistical significant benefit as measured by change in baseline in HAM-D total score; whereas casopitant at 80?mg achieved statistically significant improvement versus placebo at week 8 (LOCF HAMD17?=??2.7, p?=?0.023). A lower dose of 30?mg showed a clear but not significant separation from placebo. However, in acute studies in insomnia, both vestipitant and casopitant at 15?mg and 30?mg, respectively, significantly reduced latency to persistent sleep, wakenings after sleep onset and increased total sleep time by similar amounts. These clinical results suggest that for major depression the receptor occupancy of an NK1 antagonist needs to be very high (almost 100%), whereas, for insomnia a lower occupation is sufficient to give clinical effect.     

Cyclopentane-based human NK1 antagonists. Part 1: discovery and initial SAR

An initial investigation of the novel cyclopentane scaffold 6 afforded low nanomolar human NK1 antagonists having enhanced water solubility properties compared to morpholine 1. A synthesis of this cyclopentane scaffold, having three contiguous chiral centers, and the unexpected determination that the 1,2-trans-2,3-trans-ring stereochemistry, as opposed to the cis-ether/phenyl configuration of the known structures 1-5, is optimal for this class of antagonist are described.     

2-Aryl indole NK1 receptor antagonists: optimisation of indole substitution

The synthesis and biological evaluation of a series of 2-aryl indoles with high affinity for the human neurokinin-1 (hNK1) receptor are reported, concentrating on optimisation of the indole substitution.     

Spirocyclic NK(1) antagonists II: [4.5]-spiroethers

A series of novel spiroether-based neurokinin-1 (NK(1)) antagonists is described. The effect of modifications to the spiroether ring and aromatic substituents are discussed, leading to the identification of compounds with high affinity and excellent CNS penetration.     

Heparin induces dimerization and confers proliferative activity onto the hepatocyte growth factor antagonists NK1 and NK2

Hepatocyte growth factor (HGF) is a potent epithelial mitogen whose actions are mediated through its receptor, the proto-oncogene c-Met. Two truncated variants of HGF known as NK1 and NK2 have been reported to be competitive inhibitors of HGF binding to c-Met, and to function as HGF antagonists (Lokker, N.A., and P.J. Godowski. 1993. J. Biol. Chem. 268: 17145-17150; Chan, A.M., J.S. Rubin, D.P. Bottaro, D.W. Hirschfield, M. Chedid, and S.A. Aaronson. 1991. Science (Wash. DC). 254:1382-1387). We show here, however, that NK1 acts as a partial agonist in mink lung cells. Interestingly, NK1, which is an HGF antagonist in hepatocytes in normal conditions, was converted to a partial agonist by adding heparin to the culture medium. The interaction of NK1 and heparin was further studied in BaF3 cells, which express little or no cell surface heparan sulfate proteoglycans. In BaF3 cells transfected with a plasmid encoding human c-Met, heparin and NK1 synergized to stimulate DNA synthesis and cell proliferation. There was no effect of heparin on the IL-3 sensitivity of BaF3-hMet cells, and no effect of NK1 plus heparin in control BaF3 cells, indicating that the response was specific and mediated through c-Met. The naturally occurring HGF splice variant NK2 also stimulated DNA synthesis in mink lung cells and exerted a heparin-dependent effect on BaF3-hMet cells, but not on BaF3-neo cells. The activating effect of heparin was mimicked by a variety of sulfated glycosaminoglycans. Mechanistic studies revealed that heparin increased the binding of NK1 to BaF3-hMet cells, stabilized NK1, and induced dimerization of NK1. Based on these studies, we propose that the normal agonist activity of NK1 and NK2 in mink lung cells is due to an activating interaction with an endogenous glycosaminoglycan. Consistent with that model, a large portion of the NK1 binding to mink lung cells could be blocked by heparin. Moreover, a preparation of glycosaminoglycans from the surface of mink lung cells induced dimerization of NK1. These data show that the activity of NK1 and NK2 can be modulated by heparin and other related glycosaminoglycans to induce proliferation in cells expressing c-Met.     

Combined NK1 and NK2 tachykinin receptor antagonists: synthesis and structure-activity relationships of novel oxazolidine analogues

We report herein the synthesis and structure-activity relationships of a series of novel oxazolidine analogues with regards to NK1 and NK2 tachykinin receptor binding affinity. Among this series of oxazolidine analogues, some compounds exhibited excellent high binding affinities for both NK1 and NK2 receptors. In addition, we describe the inhibitory effect in vivo on SP-induced airway vascular hyperpermeability and NKA-induced bronchoconstriction in guinea pigs.