Inhibition of eosinophilia in vivo by a small molecule inhibitor of very late antigen (VLA)-4.

The alpha4beta1 integrin (very late antigen-4, VLA-4) plays an important role in the migration of lymphocytes, monocytes, and eosinophils, but not neutrophils, to sites of inflammation. Pharmacological antagonism of VLA-4 is an attractive prospect for the treatment of predominantly eosinophil mediated diseases such as asthma and allergic rhinitis. We report here on a potent and selective, small molecule VLA-4 inhibitor, (2S)-3-(2', 5'-dichlorobiphenyl-4-yl)-2-({[1-(2-methoxybenzoyl)piperidin-3-yl]carbonyl}amino) propanoic acid, compound 1, and characterize the antagonist activities of this molecule in various cell-based assays and in an animal model of eosinophil migration. Compound 1 inhibited VLA-4/ vascular cell adhesion molecule-1(VCAM-1) interactions with in vitro potencies (IC50 value of 210 nM) in VLA-4-expressing Ramos cells, although the compound did not inhibit cell adhesion to fibronectin via alpha5beta1 integrin (very late antigen-5, VLA-5). Blockade of phorbol-12-myristate-13-acetate (PMA)- or Mn2+-stimulated VLA-4 interactions with compound 1 was observed in human T lymphocytes (IC50 value of 230 nM), human eosinophils (IC50 value of 4.0 microM) and mouse eosinophils (IC50 value of 1.6 microM). Furthermore, compound 1 administered by intraperitoneal injection inhibited eosinophil infiltration in a dose-dependent manner by up to 80% in an air pouch model. These data support the use of small molecule VLA-4 antagonists in the treatment of relevant diseases, such as asthma, atopic dermatitis, or allergic rhinitis.

Discovery and evaluation of terephthalic acid derivatives as potent alpha4beta1 integrin antagonists.

Terephthalic acid based derivatives containing beta- and gamma-amino acid residues were prepared as antagonists of the leukocyte cell adhesion process that is mediated through the interaction of the very late antigen 4 (VLA-4) and the vascular cell adhesion molecule 1 (VCAM-1). The compounds 2, 10-12, 14, and 16-17 inhibited the adhesion in a cell based assay in the low and sub micromolar range.

Stereoselective Synthesis of 4'-Benzophenone-Substituted Nucleoside Analogs: Photoactive Models for Ribonucleotide Reductases.

Ribonucleotide reductases (RNRs) catalyze the 2'-reduction of ribonucleotides, thus providing 2'-deoxyribonucleotides, the monomers for DNA biosynthesis. The current mechanistic hypothesis for the catalysis effected by this class of enzymes involves a sequence of radical reactions. A reversible 3'-hydrogen abstraction, effected by a radical at the enzyme's active site, is believed to initiate the catalytic cycle. For the study of this substrate-enzyme interaction, a series of 4'-benzophenone-substituted model compounds was designed and synthesized. In these models, the benzophenone carbonyl group is oriented such that irradiation is expected to result in an enzyme-like, reversible 3'-hydrogen abstraction. The key step of our synthetic approach is the highly diastereoselective (dr > 95:5) Grignard-addition of carbonyl-protected o-benzophenone magnesium bromide to 2,3-O-isopropylidene-beta-L-erythrofuranose. The configuration of the newly established chiral center was unambiguously proven by X-ray crystallography. The erythritol derivative thus obtained was dehydrated to a base-free, 4'-benzophenone-substituted nucleoside analog. This first model system was further modified by transforming the free 2',3'-hydroxyl groups into the mono- and bis-methyl ethers, into the cyclic carbonate, and into the mono- and bis-mesylates. Alternatively, the primary hydroxyl group of the erythritol intermediate was selectively oxidized to the aldehyde. In the furanose thus obtained, the stage is set for the additional introduction of a nucleobase at the 1'-position.