Usha Kidambi

The discovery of sulfonylated dipeptides as Potent VLA-4 antagonists

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.

Specific and dual antagonists of α4β1 and α4β7 integrins

N-(3,5-Dichlorophenylsulfonyl)-(R)-thioprolyl biarylalanine 10a has been identified as a potent and specific antagonist of the α4β1 integrin. Altering the configuration of thioproline from R to S led to a series of dual antagonists of α4β1 and α4β7, and the N-acetyl analogue 8b was found to be the most potent dual antagonist. A binding site model for α4β1 and α4β7 is proposed to explain the structure–activity relationship.

N-Tetrahydrofuroyl-(l)-phenylalanine derivatives as potent VLA-4 antagonists

Given the proposed involvement of VLA-4 in inflammatory processes, a program to identify orally active VLA-4 antagonists was initiated. Herein, we report the discovery of a N-tetrahydrofuroyl-(L)-phenylalanine derivative (17) and related analogues as potent VLA-4 antagonists with good oral bioavailability.

The discovery of acylated β-amino acids as potent and orally bioavailable VLA-4 antagonists

Acylated beta-amino acids are described as potent, specific and orally bioavailable antagonists of VLA-4. The initial lead was identified from a combinatorial library. Subsequent optimization using a traditional medicinal chemistry approach led to significant improvement in potency (up to 8-fold) while maintaining good pharmacokinetic properties.

The discovery of small molecule carbamates as potent dual α4β1/α4β7 integrin antagonists

The alpha(4)beta(1) and alpha(4)beta(7) integrins are implicated in several inflammatory disease states. Systematic SAR studies of an alpha(4)beta(1)-specific arylsulfonyl-Pro-Tyr lead led to the identification of a new alpha(4)beta(7) binding site, best captured by O-carbamates of Tyr for this structural class. Several compounds showed a 200- to 400-fold improvement in alpha(4)beta(7) binding affinity while maintaining subnanomolar alpha(4)beta(1) activity, for example 2l, VCAM-Ig alpha(4)beta(1) IC(50)=0.13 nM, VCAM-Ig alpha(4)beta(7) IC(50)=1.92 nM.

Substituted N-(3,5-dichlorobenzenesulfonyl)-L-prolyl-phenylalanine analogues as potent VLA-4 antagonists.

A series of substituted N-(3,5-dichlorobenzenesulfonyl)-L-prolyl- and alpha-methyl-L-prolyl-phenylalanine derivatives was prepared as VLA-4/VCAM antagonists. The compounds showed excellent potency with a wide variety of neutral, polar, electron withdrawing or donating groups on the phenylalanine ring (IC50 approximately 1 nM). Heteroaryl ring substitution for phenylalanine was also well tolerated. Pharmacokinetic studies in rat were performed on a representative set of compounds in both series.

Substituted tetrahydrofuroyl-1-phenylalanine derivatives as potent and specific VLA-4 antagonists.

A series of substituted tetrahydrofuroyl-1-phenylalanine derivatives was prepared and evaluated as VLA-4 antagonists. Substitution of the alpha carbon of the tetrahydrofuran with aryl groups increased the specificity for VLA-4 versus alpha(4)beta(7) while amide substitution increased the potency of the series without increasing the specificity. Substitution of the beta carbon of the tetrahydrofuran with keto or amino groups slightly improved the specificity for VLA-4 versus alpha(4)beta(7) but with a significant loss in binding affinity for VLA-4.

N-Aryl-prolyl-dipeptides as potent antagonists of VLA-4

The design, synthesis, and biological evaluation of N-arylprolyl-dipeptide derivatives as small molecule VLA-4 antagonists is described. Potency against VLA-4 and alpha(4)beta(7) and rat pharmacokinetic evaluation revealed some advantages over the related N-(arylsulfonyl)-prolyl-dipeptide analogues.

Substituted 3-amino biaryl propionic acids as potent VLA-4 antagonists

A series of substituted N-(3,5-dichlorobenzenesulfonyl)-(L)-prolyl- and (L)-azetidyl-beta-biaryl beta-alanine derivatives was prepared as selective and potent VLA-4 antagonists. The 2,6-dioxygenated biaryl substitution pattern is important for optimizing potency. Oral bioavailability was variable and may be a result of binding to circulating plasma proteins.