ABSTRACT
A series of indole and carbazole based inhibitors of factor Xa (FXa) has been investigated. The most potent compound inhibits FXa with a Ki of 0.2 nM and has 900- and 750-fold selectivity over thrombin and trypsin, respectively.
Subject(s)
Amidines/chemistry , Anticoagulants/chemical synthesis , Anticoagulants/pharmacology , Carbazoles/chemical synthesis , Carbazoles/pharmacology , Factor Xa Inhibitors , Indoles/chemical synthesis , Indoles/pharmacology , Pyridines/chemistry , Carbazoles/chemistry , Chemical Phenomena , Chemistry, Physical , Crystallography, X-Ray , Humans , Indoles/chemistry , Models, Molecular , Molecular Conformation , Structure-Activity Relationship , Thrombin/antagonists & inhibitors , Trypsin Inhibitors/chemical synthesis , Trypsin Inhibitors/pharmacologyABSTRACT
Factor Xa is a serine protease which activates thrombin (factor IIa) and plays a key regulatory role in the blood-coagulation cascade. Factor Xa is, therefore, an important target for the design of anti-thrombotics. Both factor Xa and thrombin share sequence and structural homology with trypsin. As part of a factor Xa inhibitor-design program, a number of factor Xa inhibitors were crystallographically studied complexed to bovine trypsin. The structures of one diaryl benzimidazole, one diaryl carbazole and three diaryloxypyridines are described. All five compounds bind to trypsin in an extended conformation, with an amidinoaryl group in the S1 pocket and a second basic/hydrophobic moiety bound in the S4 pocket. These binding modes all bear a resemblance to the reported binding mode of DX-9065a in bovine trypsin and human factor Xa.
Subject(s)
Factor Xa Inhibitors , Trypsin/chemistry , Animals , Cattle , Crystallography, X-Ray , Drug Design , Electrochemistry , Humans , In Vitro Techniques , Macromolecular Substances , Models, Molecular , Molecular Conformation , Protein Binding , Protein ConformationABSTRACT
A novel series of 2,6-diphenoxypyridines has been designed to inhibit factor Xa, a serine protease strategically located in the coagulation cascade. The evolution from the photochemically unstable bisamidine (Z,Z)-BABCH to potent bisamidine compounds with a pyridine heterocycle as the core scaffold has been achieved. The most potent compound in the series, 6h, has a Ki for human factor Xa of 12 nM. The selectivity of 6h against bovine trypsin and human thrombin was greater than 90- and 1000-fold, respectively. Two proposed modes of binding of 6h to factor Xa are made based on the crystal structures of 6h by itself and of 6h bound to bovine trypsin.
Subject(s)
Amidines/chemical synthesis , Factor Xa Inhibitors , Fibrinolytic Agents/chemical synthesis , Pyridines/chemical synthesis , Amidines/chemistry , Animals , Cattle , Crystallography, X-Ray , Drug Design , Fibrinolytic Agents/chemistry , Humans , Models, Molecular , Molecular Conformation , Pyridines/chemistry , Stereoisomerism , Structure-Activity Relationship , Thrombin/antagonists & inhibitors , Trypsin Inhibitors/chemical synthesis , Trypsin Inhibitors/chemistryABSTRACT
Factor Xa (FXa) is a trypsin-like serine protease that plays a key role in blood coagulation linking the intrinsic and extrinsic pathways to the final common pathway of the coagulation cascade. During our initial studies, we observed facile photochemical conversion of the known FXa/tPA inhibitor, BABCH ¿(E,E)-2, 7-bis(4-amidinobenzylidene)cycloheptan-1-one, 1a, to the corresponding (Z,Z) olefin isomer, 1c (FXa K(i) = 0.66 nM), which was over 25,000 times more potent than the corresponding (E,E) isomer (1a, FXa K(i) = 17 000 nM). In order to determine the scope of this observation, we expanded on our initial investigation through the preparation of the olefin isomers in a homologous series of cycloalkanone rings, 4-substituted cyclohexanone analogues, and modified amidine derivatives. In most cases the order of potency of the olefin isomers was (Z,Z) > (E,Z) > (E,E) with the cycloheptanone analogue (1c) showing the most potent factor Xa inhibitory activity. In addition, we found that selectivity versus thrombin (FIIa) can be dramatically improved by the addition of a carboxylic acid group to the cycloalkanone ring as seen with 8c (FXa K(i) = 6.9 nM, FIIa K(i) > 50,000 nM). Compounds with one or both of the amidine groups substituted with N-alkyl substituents or replaced with amide groups led to a significant loss of activity. In this report we have demonstrated the importance of the two amidine groups, the cycloheptanone ring, and the (Z,Z) olefin configuration for maximum inhibition of FXa within the BABCH template. The results from this study provided the foundation for the discovery of potent, selective, and orally active FXa inhibitors.
Subject(s)
Benzylidene Compounds/chemical synthesis , Benzylidene Compounds/pharmacology , Factor Xa Inhibitors , Serine Proteinase Inhibitors/chemical synthesis , Serine Proteinase Inhibitors/pharmacology , Benzylidene Compounds/chemistry , Humans , Magnetic Resonance Spectroscopy , Serine Proteinase Inhibitors/chemistry , Structure-Activity RelationshipSubject(s)
Amidines/chemical synthesis , Anticoagulants/chemical synthesis , Factor Xa Inhibitors , Pyridines/chemical synthesis , Serine Proteinase Inhibitors/chemical synthesis , Administration, Oral , Amidines/chemistry , Amidines/pharmacokinetics , Amidines/pharmacology , Animals , Anticoagulants/chemistry , Anticoagulants/pharmacokinetics , Anticoagulants/pharmacology , Benzylidene Compounds/chemical synthesis , Benzylidene Compounds/chemistry , Benzylidene Compounds/pharmacokinetics , Benzylidene Compounds/pharmacology , Binding Sites , Biological Availability , Cattle , Crystallography, X-Ray , Dogs , Drug Evaluation, Preclinical , Humans , Injections, Intravenous , Macaca fascicularis , Models, Molecular , Molecular Conformation , Papio , Pyridines/chemistry , Pyridines/pharmacokinetics , Pyridines/pharmacology , Serine Proteinase Inhibitors/chemistry , Serine Proteinase Inhibitors/pharmacokinetics , Serine Proteinase Inhibitors/pharmacology , Stereoisomerism , Structure-Activity Relationship , Thrombin/antagonists & inhibitors , Trypsin Inhibitors/chemical synthesis , Trypsin Inhibitors/chemistry , Trypsin Inhibitors/pharmacokinetics , Trypsin Inhibitors/pharmacologyABSTRACT
The synthesis of amidinoaryloxy 9-benzyl-8-methyl-9H-purine, 7,8-dihydropteridine-6(5H)-one and 5,7-dihydropyrimido[4,5-b][1,4]oxazine-6-one inhibitors of Factor Xa is described. These compounds show nanomolar potency against FXa and maintain high selectivity over thrombin and trypsin.