ABSTRACT
The structure-activity relationship of Rho kinase inhibitors bearing an isoquinoline scaffold was studied. N-(1-Benzyl-3-pyrrolidyl)-N-(5-isoquinolyl)amine analogues were optimized with respect to their inhibitory potencies for the enzyme and for chemotaxis. The potent analogues were further evaluated by an ex vivo test in which the selected compounds were orally administered to rats, and the Rho kinase inhibitory potency observed in the rat serum was evaluated 3h after the administration. Compound 23g showed a high level of Rho kinase inhibitory activity in the rat serum and was stable in an in vitro metabolic test using a microsomal cytochrome preparation. The (R)-isomer of 23g displayed a higher level of inhibitory potency than the (S)-isomer in a cell-free kinase assay and in the cell migration assay (IC(50)(ENZ)=25 nM and IC(50)(MCP)=1 microM). The (R)-isomer successfully inhibited the phosphorylation of MBS (myosin-binding subunit) in cells.
Subject(s)
Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/pharmacology , Intracellular Signaling Peptides and Proteins/antagonists & inhibitors , Isoquinolines/chemical synthesis , Isoquinolines/pharmacology , Protein Serine-Threonine Kinases/antagonists & inhibitors , Alkylation , Animals , Cell Line , Chemotaxis, Leukocyte/drug effects , Dogs , Drug Design , In Vitro Techniques , Kidney/drug effects , Kidney/enzymology , Ligands , Magnetic Resonance Spectroscopy , Microsomes, Liver/drug effects , Microsomes, Liver/enzymology , Models, Molecular , Oxidation-Reduction , Phosphorylation , Rats , Rats, Sprague-Dawley , Spectrometry, Mass, Electrospray Ionization , Structure-Activity Relationship , rho-Associated KinasesABSTRACT
In a previous study, we identified several structurally unrelated scaffolds of the Rho kinase inhibitor using pharmacophore information obtained from the results of a high-throughput screening and structural information from a homology model of Rho kinase. 1H-Indazole is one of the candidate scaffolds on which a new series of potent Rho kinase inhibitors could be developed. In this study, the detailed structure-activity relationship of 1H-indazole analogues was studied. During this study, we found that the cell-free enzyme inhibitory potential of Rho kinase inhibitors having the 1H-indazole scaffold did not necessarily correlate with their inhibitory potential toward the chemotaxis of cultured cells. The choice of the linker substructure was shown to be an important factor for the 1H-indazole analogues to inhibit the chemotaxis of cells. Optimization of the 1H-indazole inhibitors with respect to the in vitro inhibition of monocyte chemotaxis induced by MCP-1 was carried out. The inhibitory potential was improved both in the cell-free enzyme assay and in the chemotaxis assay.
Subject(s)
Indazoles/chemical synthesis , Intracellular Signaling Peptides and Proteins/antagonists & inhibitors , Protein Kinase Inhibitors/chemical synthesis , Protein Serine-Threonine Kinases/antagonists & inhibitors , Binding Sites , Cell Line, Tumor , Chemotaxis/drug effects , Drug Design , Drug Evaluation, Preclinical , Humans , Indazoles/chemistry , Indazoles/pharmacology , Ligands , Models, Molecular , Molecular Structure , Monocytes/drug effects , Protein Kinase Inhibitors/chemistry , Protein Kinase Inhibitors/pharmacology , Stereoisomerism , Structure-Activity Relationship , rho-Associated KinasesABSTRACT
Several structurally unrelated scaffolds of the Rho kinase inhibitor were designed using pharmacophore information obtained from the results of a high-throughput screening and structural information from a homology model of Rho kinase. A docking simulation using the ligand-binding pocket of the Rho kinase model helped to comprehensively understand and to predict the structure-activity relationship of the inhibitors. This understanding was useful for developing new Rho kinase inhibitors of higher potency and selectivity. We identified several potent platforms for developing the Rho kinase inhibitors, namely, pyridine, 1H-indazole, isoquinoline, and phthalimide.
