MEN16132, a novel potent and selective nonpeptide antagonist for the human bradykinin B₂ receptor. In vitro pharmacology and molecular characterization

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• 作者：Paola Cucchi ; Stefania Meini ; Alessandro Bressan ; Claudio Catalani ; Francesca Bellucci ; Paolo Santicioli ; Alessandro Lecci ; Angela Faiella ; Luigi Rotondaro ; Sandro Giuliani et al.
• 关键词：Binding site ; Cyclic peptide ; G protein-coupled receptor ; Icatibant ; Site-directed mutagenesis
• 刊名：European Journal of Pharmacology
• 出版年：2005
• 出版时间：28 December 2005
• 年：2005
• 卷：528
• 期：1-3
• 页码：7-16
• 全文大小：211 K

文摘

The pharmacological characterization of the novel nonpeptide antagonist for the B₂ receptor, namely MEN16132 (4-(S)-Amino-5-(4-{4-[2,4-dichloro-3-(2,4-dimethyl-8-quinolyloxymethyl)phenylsulfonamido]-tetrahydro-2H-4-pyranylcarbonyl}piperazino)-5-oxopentyl](trimethyl)ammonium chloride hydrochloride) is presented.

The affinity of MEN16132 for the bradykinin B₂ receptor has been investigated by means of competition studies at [³H]bradykinin binding to membranes prepared from Chinese Hamster Ovary (CHO) cells expressing the human bradykinin B₂ receptor (pK_i 10.5), human lung fibroblasts (pK_i 10.5), guinea pig airways (pK_i 10.0), guinea pig ileum longitudinal smooth muscle (pK_i 10.2), or guinea pig cultured colonic myocytes (pK_i 10.3). In all assays MEN16132 was as potent as the peptide antagonist Icatibant, and from 3- to 100-fold more potent than the reference nonpeptide antagonists FR173657 or LF16-0687. The selectivity for the bradykinin B₂ receptor was checked at the human bradykinin B₁ receptor (pK_i < 5), and at a panel of 26 different receptors and channels.

The antagonist potency was measured in functional assays, i.e., in blocking the bradykinin induced inositolphosphates (IP) accumulation at the human (CHO: pK_B 10.3) and guinea pig (colonic myocytes: pK_B 10.3) B₂ receptor, or in antagonizing the bradykinin induced contractile responses in human (detrusor smooth muscle: pK_B 9.9) and guinea pig (ileum longitudinal smooth muscle: pK_B 10.1) tissues. In both functional assay types MEN16132 exerted a different antagonist pattern, i.e., surmountable at the human and insurmountable at the guinea pig bradykinin B₂ receptors.

Moreover, the receptor determinants important for the high affinity interaction of MEN16132 with the human bradykinin B₂ receptor were investigated by means of radioligand binding studies performed at 24 point-mutated receptors. The results obtained revealed that residues in transmembrane segment 2 (W86A), 3 (I110A), 6 (W256A), and 7 (Y295A, Y295F but not much Y295W), were crucial for the high affinity of MEN16132. In conclusion, MEN16132 is a new, potent, and selective nonpeptide bradykinin B₂ receptor antagonist.