Phenethyl amides as novel noncovalent inhibitors of hepatitis C virus NS3/4A protease: discovery, initial SAR, and molecular modeling.

The discovery of novel, reversible and competitive tripeptide inhibitors of the Hepatitis C virus NS3/4A serine protease is described. These inhibitors are characterized by the presence of a C-terminal phenethyl amide group, which extends into the prime side of the enzyme. Initial SAR together with molecular modeling and data from site-directed mutagenesis suggest an interaction of the phenethyl amide group with Lys-136.

Evolution, synthesis and SAR of tripeptide alpha-ketoacid inhibitors of the hepatitis C virus NS3/NS4A serine protease.

N-terminal truncation of the hexapeptide ketoacid 1 gave rise to potent tripeptide inhibitors of the hepatitis C virus NS3 protease/NS4A cofactor complex. Optimization of these tripeptides led to ketoacid 30 with an IC50 of 0.38 microM.

A designed P1 cysteine mimetic for covalent and non-covalent inhibitors of HCV NS3 protease.

The difluoromethyl group was designed by computational chemistry methods as a mimetic of the canonical P1 cysteine thiol for inhibitors of the hepatitis C virus NS3 protease. This modification led to the development of competitive, non-covalent inhibitor 4 (K(i) 30 nM) and reversible covalent inhibitors (6, K(i) 0.5 nM; and 8 K*(i) 10 pM).