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This letter describes the discovery of a novel series of tetrahydroisoquinoline (THIQ)-derived small molecules that potently inhibit both human T-cell migration and super-antigen induced T-cell activation through disruption of the binding of integrin LFA-1 to its receptor, ICAM-1. In addition to excellent in vitro potency, 6q shows good pharmacokinetic properties and its ethyl ester (6t) demonstrates good oral bioavailability in both mouse and rat. Either intravenous administration of 6q or oral administration of its ethyl ester (6t) produced a significant reduction of neutrophil migration in a thioglycollate-induced murine peritonitis model., (Copyright 2010 Elsevier Ltd. All rights reserved.)

LFA-1 ICAM inhibitors based on ortho- and meta-phenol templates were designed and synthesized by Mitsunobu chemistry. The selection of targets was guided by X-ray co-crystal data, and led to compounds which showed an up to 30-fold increase in potency over reference compound 1 in the LFA-1/ICAM1-Ig assay. The most active compound exploited a new hydrogen bond to the I-domain and exhibited subnanomolar potency.

A series of meta-substituted anilines were designed and synthesized to inhibit the interaction of LFA-1 with ICAM for the treatment of autoimmune disease. Design of these molecules was performed by utilizing a co-crystal structure for structure-based drug design. The resulting molecules were found to be potent and to possess favorable pharmaceutical properties.

2-Amino-4-phenyl pyridine and, to a lesser extent, 4-amino-6-phenyl pyrimidine, were established as isosteres of trans-cinnamide moiety. Applying this isosterism to previously reported p-arylthio cinnamides resulted in the identification of 4-amino-6-(p-arylthio)phenyl-pyrimidines and 2-amino-4-(p-arylthio)phenyl-pyridines as potent antagonists of LFA-1/ICAM-1 binding.

The cyclic depsipeptide HUN-7293 (1) and its D-lactate analogue 2 are highly potent inhibitors of inducible cell adhesion molecule expression. We report the synthesis of ether analogues varying in stereochemistry and side chain at the former hydroxyl acid position by employing a 'cut and paste chemistry' methodology starting from 1. As an additional fruit of this synthetic effort, a cyclodepsipeptide featuring a tertiary amine instead of a tertiary amide between PrLEU and MALA was obtained. Results on the inhibitory profile of these compounds in assays of VCAM-1 and ICAM-1 protein expression are discussed.

Modification of the vanillyl substituent on a potent, semisynthetic lymphocyte function-associated antigen (LFA)-1/intercellular adhesion molecule (ICAM)-1 binding inhibitor of the statin family resulted in metabolically more stable analogues that displayed submicromolar inhibitory activity in vitro and considerable anti-inflammatory activity in vivo. The benzodioxole derivative 2b emerged with the best overall profile.

o-Bromobenzoyl l-tryptophan 1 inhibits the association of LFA-1 with ICAM-1 with an IC(50) of 1.7microM. Evaluation of the structure-activity relationship of the benzoyl moiety shows that 2,6-di-substitutions greatly enhance potency of this class of inhibitors. Electronegative substitutions that favor a 90 degrees angle between the benzoyl ring and the amide bond yield the most potent compounds. There is a strong correlation between the potency of the compounds and the difference between the ab initio energy at 90 degrees and the global minima energy for given compounds. Combining the favored benzoyl substitutions with l-histidine and l-asparagine resulted in a 15-fold increase in potency over compound 1.

The association of ICAM-1 with LFA-1 plays a critical role in several autoimmune diseases. N-2-Bromobenzoyl L-tryptophan, compound 1, was identified as an inhibitor to the formation of the LFA-1/ICAM complex. The SAR of the amino acid indicates that the carboxylic acid is required for inhibition and that L-histidine is the most favored amino acid.

The design, synthesis, and biological evaluation of 1,4-diazepane-2-ones as novel LFA-1 antagonists from a scaffold-based combinatorial library are described. Initial optimization of the library lead has resulted in high-affinity antagonists of the LFA-1/ICAM-1 interaction, such as compounds 18d and 18e with IC(50) values of 110 and 70 nM, respectively.

A series of nitrobenzene compounds has been discovered as potent inhibitors of VCAM-1 expression and, therefore, potential drug candidates for autoimmune and allergic inflammatory diseases. Structure-activity relationship (SAR) studies showed that a nitro group and two other electron-withdrawing groups are essential for these compounds to be potent inhibitors of VCAM-1 expression.

Diarylsulfide cyclopropylamides were synthesized and evaluated as LFA-1/ICAM-1 interaction antagonists. A substituent pattern was identified which maximized potency and minimized protein binding as exemplified by antagonist 30 (IC50 = 5 nM).