Authors: Nitsche, Christoph; Schreier, Verena N.; Behnam, Mira A. M.; Kumar, Anil; Bartenschlager, Ralf; Klein, Christian D.; Journal of Medicinal Chemistry; (2013); 10.1021/jm400828u
The protease of dengue virus is a promising target for antiviral drug discovery. We here report a new generation of peptide-hybrid inhibitors of dengue protease that incorporate N-substituted 5-arylidenethiazolidinone heterocycles (rhodanines and thiazolidinediones) as N-terminal capping groups of the peptide moiety. The compounds were extensively characterized with respect to inhibition of various proteases, inhibition mechanisms, membrane permeability, antiviral activity, and cytotoxicity in cell culture. A sulfur/oxygen exchange in position 2 of the capping heterocycle (thiazolidinedione-capped vs rhodanine-capped peptide hybrids) has a significant effect on these properties and activities. The most promising in vitro affinities were observed for thiazolidinedione-based peptide hybrids containing hydrophobic groups with Ki values between 1.5 and 1.8 ?M and competitive inhibition mechanisms. Rhodanine-capped peptide hybrids with hydrophobic substituents have, in correlation with their membrane permeability, a more pronounced antiviral activity in cell culture than the thiazolidinediones.