ABSTRACT
Directed screening of a carboxylic acid-containing combinatorial library led to the discovery of potent inhibitors of the integrin VLA-4. Subsequent optimization by solid-phase synthesis afforded a series of sulfonylated dipeptide inhibitors with structural components that when combined in a single hybrid molecule gave a sub-nanomolar inhibitor as a lead for medicinal chemistry. Preliminary metabolic studies led to the discovery of substituted biphenyl derivatives with low picomolar activities. SAR and pharmacokinetic characterization of this series are presented.
Subject(s)
Dipeptides/pharmacology , Integrins/antagonists & inhibitors , Receptors, Lymphocyte Homing/antagonists & inhibitors , Sulfonic Acids/chemistry , Animals , Biological Availability , Dipeptides/chemistry , Dipeptides/pharmacokinetics , Dogs , Integrin alpha4beta1 , Integrins/metabolism , Macaca mulatta , Metabolic Clearance Rate , Rats , Receptors, Lymphocyte Homing/metabolism , Structure-Activity RelationshipABSTRACT
Carboxyalkyl peptides containing a biphenylylethyl group at the P1' position were found to be potent inhibitors of stromelysin-1 (MMP-3) and gelatinase A (MMP-2), in the range of 10-50 nM, but poor inhibitors of collagenase (MMP-1). Combination of a biphenylylethyl moiety at P1', a tert-butyl group at P2', and a methyl group at P3' produced orally bioavailable inhibitors as measured by an in vivo model of MMP-3 degradation of radiolabeled transferrin in the mouse pleural cavity. The X-ray structure of a complex of a P1-biphenyl inhibitor and the catalytic domain of MMP-3 is described. Inhibitors that contained halogenated biphenylylethyl residues at P1' proved to be superior in terms of enzyme potency and oral activity with 2(R)-[2-(4'-fluoro-4-biphenylyl)ethyl]-4(S)-n-butyl-1,5-pentane dioic acid 1-(alpha(S)-tert-butylglycine methylamide) amide (L-758,354, 26) having a Ki of 10 nM against MMP-3 and an ED50 of 11 mg/kg po in the mouse pleural cavity assay. This compound was evaluated in acute (MMP-3 and IL-1 beta injection in the rabbit) and chronic (rat adjuvant-induced arthritis and mouse collagen-induced arthritis) models of cartilage destruction but showed activity only in the MMP-3 injection model (ED50 = 6 mg/kg iv).
Subject(s)
Dipeptides/pharmacology , Matrix Metalloproteinase Inhibitors , Protease Inhibitors/pharmacology , Animals , Arthritis/drug therapy , Binding Sites , Cartilage/drug effects , Crystallography, X-Ray , Dipeptides/chemical synthesis , Dipeptides/chemistry , Dipeptides/metabolism , Disease Models, Animal , Gelatinases/antagonists & inhibitors , Interleukin-1/administration & dosage , Interleukin-1/pharmacology , Magnetic Resonance Spectroscopy , Matrix Metalloproteinase 1 , Matrix Metalloproteinase 2 , Metalloendopeptidases/antagonists & inhibitors , Mice , Models, Molecular , Molecular Structure , Protease Inhibitors/chemical synthesis , Protease Inhibitors/chemistry , Protease Inhibitors/metabolism , Rabbits , Rats , Recombinant Proteins/antagonists & inhibitors , Structure-Activity Relationship , Transferrin/metabolism , Zinc/chemistry , Zinc/metabolismABSTRACT
Losartan, an antihypertensive agent in clinical development, was found to exist in two enantiotropic polymorphic forms, a low-temperature stable form (Form I) and a high-temperature stable form (Form II), the temperatures at which they are stable being related to the transition temperature. X-ray powder diffraction patterns indicated differences in the crystal packing of the two forms. The vibrational data from infrared and Raman spectroscopy suggested a subtle change in molecular conformation and crystal packing in the two forms. Solid-state 13C NMR data of the polymorphs concurred with the vibrational data and indicated that, while the observed line widths reflect no major changes in crystallinity, signal multiplicities and chemical shifts do reflect differences in molecular packing in the respective unit cells. Thus, in the absence of crystallographic data, useful structural information could be derived from spectroscopic results to identify each of the crystalline forms.
