wms-1410 and ifenprodil

In order to analyze the role of the phenolic OH moiety of ifenprodil (1) and 3-benzazepin-1,7-diol 2 for the affinity and selectivity at GluN2B subunit containing NMDA receptors, the 3-benzazepin-1-ols 3 were designed, synthesized and pharmacologically evaluated and furthermore, the molecular interactions of the phenylbutyl derivative 3c with the GluN2B receptor were investigated. In order to avoid decarbonylation during the intramolecular Friedel-Crafts acylation of 11, the N-atom has to be protected with a trifluoromethylsulfonyl group. The second key step of the synthesis was the removal of the N-triflyl group, which was realized by K2CO3 induced elimination of trifluoromethanelsulfinate (F3CSO2(-)). In receptor binding studies with the radioligand [(3)H]ifenprodil the 3-benzazepin-1-ol 3c revealed a GluN2B affinity of 73 nM indicating that the phenolic OH moiety of 1 and 2 is not essential but favorable for high GluN2B affinity. In docking studies 3-benzazepin-1-ol 3c shows the same binding pose as ifenprodil-keto 1A in the X-ray crystal structure. H-bond interactions and lipophilic interactions of 3c and 1A are very similar.

Topics: Benzazepines; Binding Sites; Humans; Kinetics; Molecular Docking Simulation; Phenols; Piperidines; Protein Structure, Tertiary; Receptors, N-Methyl-D-Aspartate; Tritium

NR2B selective NMDA receptor antagonists with tetrahydro-3-benzazepine-1,7-diol scaffold have been designed by formal cleavage and reconstitution of the piperidine ring of the lead compound ifenprodil (1). The secondary amine 10 represents the central building block for the synthesis of more than 25 tetrahydro-3-benzazepin-1-ols. Generally 7-hydroxy derivatives display higher NR2B receptor affinities than the corresponding 7-benzyloxy compounds. A distance of four atoms (five bond lengths) between the basic amino group and the terminal aryl moiety led to highest NR2B affinity. 3-(4-Phenylbutyl)-2,3,4,5-tetrahydro-1H-3-benzazepine-1,7-diol (WMS-1410, 25) represents the most promising NR2B antagonist of this series showing a K(i)-value of 14nM. Compound 25 reveals excellent selectivity over more than 100 further relevant target proteins, antagonizes glutamate induced excitotoxicity (IC(50)=18.4nM) and is metabolically more stable than ifenprodil. Up to a dose of 100mg/kg 25 is well tolerated by mice and it shows dose dependent analgesic activity in the late neuropathic pain phase of the formalin assay.

Topics: Analgesics; Animals; Benzazepines; Humans; Mice; Microsomes, Liver; Neuralgia; Piperidines; Rats; Receptors, N-Methyl-D-Aspartate; Structure-Activity Relationship