The identification of an orally active, nonpeptide bradykinin B 2 receptor antagonist, FR173657 (original) (raw)
Related papers
A non-peptide antagonist unusually selective for the human form of the bradykinin B2 receptor
International Immunopharmacology, 2003
Analgesic and anti-inflammatory applications for non-peptide bradykinin (BK) B 2 receptor antagonists have been documented in rats. However, very large species differences in affinity were also noted within this class of drugs, making the preclinical development of relevant drugs difficult. Bradyzide is a potent antagonist at the rat B 2 receptor, but a weak one at the human receptor; a series of analogues in which the diphenylmethyl moiety of this drug has been substituted with dibenzosuberane have been reported to gain potency at the human B 2 receptor, with some loss of affinity at the rat receptor. The present experiments have been performed in order to verify that the novel series of dibenzosuberane B 2 receptor antagonist optimized for affinity in the human species are effective in the isolated human umbilical vein contractility assay. Bradyzide, its analog compound (S)-14c and the dibenzosuberane compounds (S)-14d and 19c surmountably antagonized BK-induced contraction (pA 2 values of 5.42, 6.48, 7.42 and 7.53, respectively). In the rabbit jugular vein contractility assay, the pA 2 of compound 19c was smaller than 5. Potency at the recombinant rabbit B 2 receptor was generally decreasing in the series of four drugs (K i in a [ 3 H]BK competition assay to recombinant receptors of 0.78, 0.77, 10.2 and 44.4 nM, respectively); these four compounds did not displace [ 3 H]Lys-des-Arg 9-BK binding from human B 1 receptors expressed by smooth muscle cells. The dibenzosuberane compound 19c, verified to functionally antagonize the vascular B 2 receptor, is an example of a drug unusually specific for the human form of the receptor.
In Vitro Pharmacological Profile of a New Small Molecule Bradykinin B2 Receptor Antagonist
Frontiers in Pharmacology, 2020
We here report the discovery and early characterization of Compound 3, a representative of a novel class of small molecule bradykinin (BK) B 2 receptor antagonists, and its superior profile to the prior art B 2 receptor antagonists Compound 1 and Compound 2. Compound 3, Compound 2, and Compound 1 are highly potent antagonists of the human recombinant B 2 receptor (K b values 0.24, 0.95, and 1.24 nM, respectively, calcium mobilization assay). Compound 3 is more potent than the prior art compounds and icatibant in this assay (K b icatibant 2.81 nM). The compounds also potently inhibit BK-induced contraction of endogenous B 2 receptors in a human isolated umbilical vein bioassay. The potencies of Compound 3, Compound 2, Compound 1, and icatibant are (pA 2 values) 9.67, 9.02, 8.58, and 8.06 (i.e. 0.21, 0.95, 2.63, and 8.71 nM), respectively. Compound 3 and Compound 2 were further characterized. They inhibit BK-induced c-Fos signaling and internalization of recombinant human B 2 receptors in HEK293 cells, and do not antagonize the venous effects mediated by other G protein-coupled receptors in the umbilical vein model, including the bradykinin B 1 receptor. Antagonist potency of Compound 3 at cloned cynomolgus monkey, dog, rat, and mouse B 2 receptors revealed species selectivity, with a high antagonist potency for human and monkey B 2 receptors, but several hundred-fold lower potency for the other B 2 receptors. The in vitro off-target profile of Compound 3 demonstrates a high degree of selectivity over a wide range of molecular targets, including the bradykinin B 1 receptor. Compound 3 showed a lower intrinsic clearance in the microsomal stability assay than the prior art compounds. With an efflux ratio of 1.0 in the Caco-2 permeability assay Compound 3 is predicted to be not a substrate of efflux pumps. In conclusion, we discovered a novel chemical class of highly selective and very potent B 2 receptor antagonists, as exemplified by Compound 3. The compound showed excellent absorption in the Caco-2 assay, predictive of good oral bioavailability, and favourable metabolic stability in liver microsomes. Compound 3 has provided a significant stepping stone towards the discovery of the orally bioavailable B 2 antagonist PHA-022121, currently in phase 1 clinical development.
British Journal of Pharmacology, 2007
Background and purpose: The aim was to characterize the recently discovered non-peptide antagonist MEN16132 at the mouse B 2 receptor, relative to other antagonists. Experimental approach: [ 3 H]-BK binding experiments used mouse lung and ileum tissue membranes and antagonist potency was measured in the isolated ileum contractility assay. Key results: Two BK binding sites resulted from saturation and homologous competition experiments. A role for the B 1 receptor was excluded because of the poor affinity of B 1 receptor ligands (pIC 50 o5). MEN16132, and the other reference antagonists, inhibited only one portion of BK specific binding, and the rank order of potency was (pIC 50 ): Icatibant (lung 10.7; ileum 10.2) ¼ MEN11270 (lung 10.4; ileum 9.9) ¼ MEN16132 (lung 10.5; ileum 9.9). 4 LF16-0687 (lung 8.9; ileum 8.8) 4 FR173657 (lung 8.6; ileum 8.2). BK homologous curves performed with lung membranes after treatment with the antagonist MEN16132 or Icatibant (10 nM) displayed only the low affinity site. The functional antagonism by MEN16132 (pA 2 9.4) and Icatibant (pA 2 9.1), towards BK (control EC 50 6.1 nM) induced ileum contractions, was concentration-dependent and surmountable, but the Schild plot slope was less than unity. Conclusions and Implications: In mouse tissue, radiolabelled BK recognizes two binding sites and B 2 receptor antagonists can compete only for the higher affinity one. The pharmacological profile of the novel non-peptide antagonist MEN16132 indicates that it exhibits subnanomolar affinity and potency for the mouse B 2 receptor and is suitable for further characterization in in vivo pathophysiological models.
Further pharmacological evaluation of a novel synthetic peptide bradykinin B2 receptor agonist
bchm, 2013
We recently identified a novel human B2 receptor (B2R) agonist [Hyp3,Thi5,NChg7,Thi8]-bradykinin (NG291) with greater in vitro and in vivo potency and duration of action than natural bradykinin (BK). Here, we further examined its stability and selectivity toward B2R. The hypotensive, antithrombotic, and profibrinolytic functions of NG291 relative to BK and its analogue ([Hyp3,Thi5,(4-Me)Tyr8(ΨCH2NH)Arg9]-BK) (RMP-7) were also tested. Contraction assays using isolated mouse stomachs (containing kinin B1R, B2R, and kininase I- and II-like activities) showed that NG291 is a more potent contractant than BK and is inhibited by HOE-140 (B2R antagonist) but unaffected by R954 (B1R antagonist), whereas both decreased the potency of BK. In stomach tissues from B2R knockout mice, BK maintained its activity via B1R, whereas NG291 had no contractile effect, indicating that it was selective for B2R. Unlike BK, NG291 was not degraded by rabbit lung ACE. Comparing intravenously administered BK and...
Fundamental & Clinical Pharmacology, 1999
Activation of the kinin-kallikrein system and stimulation of hradykinin (BK) B, receptors are thought to play an important role in the pathophysiology of inflammation and pain. In the present study, we report the pharmacological properties of a novel nonpeptide bradykinin B, receptor antagonist, L F 16-033SC, ( 1 -[[3-[(2,4-dimethylquinolin-8-yl)oxymethyl]-2,4-dichloro-phenyl]sulfonyl]-2(S)-[~4-~4-(aminoiminomethyl)-phenylcarbonyl]piperazin-1 -yl]carbonyl]pyrrolidine, 2HCI). In binding studies, L F 16-033SC competed with ['Hlbradykinin giving K, values of 1.65 f 0.36 nM and 2.20 t 0.30 nM in membrane preparations from rat uterus (RU) and guinea-pig ileum (GPI), respectively. In functional experiments, LF 16-033SC inhibited in a competitive manner BK-induced contractions of both isolated RU and GPI, leading to calculated PA, values of 7.70 k 0.70 and 8.30 k 0.30, respectively. The inhibitory effect of LF 16-033SC was
New conformationally homogeneous ?-turn antagonists of the human B2 kinin receptor
Journal of Peptide Science, 2001
We have designed and synthesized a conformationally homogeneous series of cyclic pentapeptides of the general structure c[Pro-aa i -D-Tic-Oic-aa i + 3 ] which adopt a type-II% i-turn conformation believed important for high affinity antagonism of the bradykinin (BK) B 2 receptor. We incorporated D-Tic and octahydroindole-2-carboxylic acid (Oic) residues (present in known active antagonists) in a cyclic pentapeptide that would place the D-aa in the i +l position of the i-turn and a proline as a bridge between the C-and N-termini sides of the turn. In positions i and i +3 alkyl, aromatic, polar or charged amino acids could be introduced without dramatically changing the overall structure. Ten analogues were studied using 1 H nuclear magnetic resonance (NMR) and evaluated for their binding affinity for the human B 2 receptor. The NMR data in dimethylsulfoxide (DMSO) confirmed the structural homogeneity within the class and, on the basis of this, one representative member of the series was chosen for a detailed structure determination using NMR data in sodium dodecylsulphate (SDS) micelles and molecular dynamics calculations. Despite the structural similarity, the binding affinity of the ten analogues was strongly influenced by the nature of the side-chains in positions i and i+ 3, with the doubly charged analogue 49 (pK i =6.2) proving best. This compound may serve as the starting point for the discovery of new non-peptide bradykinin B 2 receptor antagonists.
Kallikrein activates bradykinin B2 receptors in the absence of kininogen
2005
Kallikreins cleave plasma kininogens to release the bioactive peptides bradykinin (BK) or kallidin (Lys-BK). These peptides then activate widely disseminated B 2 receptors with consequences that may be either noxious or beneficial. We used cultured cells to show that kallikrein can bypass kinin release to activate BK B 2 receptors directly. To exclude intermediate kinin release or kininogen uptake from the culture medium, we cultured and maintained cells in medium entirely free of animal proteins. We compared the responses of stably transfected CHO cells that express human B 2 receptors (CHO-B 2 ) and cells that co-express angiotensin Iconverting enzyme (ACE) as well (CHO AB). We found that BK (1 nM or more) and tissue kallikrein (1-10 nM) both significantly increased release of arachidonic acid beyond unstimulated or baseline levels. An enzyme-linked immunoassay for kinin established that kallikrein did not release a kinin from CHO cells. We confirmed the absence of kininogen mRNA with RT-PCR to rule out kininogen synthesis by CHO cells. Next, we tested an ACE inhibitor for enhanced BK receptor activation in the absence of kinin release and synthesized an ACE-resistant BK analogue as a control for these experiments. Enalaprilat (1µM) potentiated kallikrein (100 nM) in CHO AB cells but was ineffective in CHO B 2 cells that do not bear ACE.