Naphthoquinones as Covalent Reversible Inhibitors of Cysteine Proteases-Studies on Inhibition Mechanism and Kinetics

• Published in: Molecules (Basel, Switzerland) Switzerland), 2020-04, Vol.25 (9), p.2064
• Main Authors: Klein, Philipp, Barthels, Fabian, Johe, Patrick, Wagner, Annika, Tenzer, Stefan, Distler, Ute, Le, Thien Anh, Schmid, Paul, Engel, Volker, Engels, Bernd, Hellmich, Ute A, Opatz, Till, Schirmeister, Tanja
• Format: Article
• Language: English
• Subjects: 1,4-naphthoquinone; Cathepsin L - chemistry; Competition; covalent reversible inhibition; Cysteine Endopeptidases - chemistry; Cysteine Proteases - chemistry; Cysteine Proteinase Inhibitors - chemical synthesis; Cysteine Proteinase Inhibitors - chemistry; Dengue fever; Dipeptides; Electrons; Enzymes; Esters; Hydrolysis; Inhibitory Concentration 50; Kinetics; Mass Spectrometry; Mass spectroscopy; Mode of action; Naphthoquinones - chemistry; nucleophilic addition; prodrug; Prodrugs - chemistry; protease; Protease inhibitors; Proteinase inhibitors; Quantum Theory; rhodesain; Structure-Activity Relationship; Trypanocidal Agents - pharmacology; Trypanosoma brucei brucei - drug effects; Wave functions
• ISSN: 1420-3049; 1420-3049
• DOI: 10.3390/molecules25092064

The facile synthesis and detailed investigation of a class of highly potent protease inhibitors based on 1,4-naphthoquinones with a dipeptidic recognition motif (HN-l-Phe-l-Leu-OR) in the 2-position and an electron-withdrawing group (EWG) in the 3-position is presented. One of the compound representatives, namely the acid with EWG = CN and with R = H proved to be a highly potent rhodesain inhibitor with nanomolar affinity. The respective benzyl ester (R = Bn) was found to be hydrolyzed by the target enzyme itself yielding the free acid. Detailed kinetic and mass spectrometry studies revealed a reversible covalent binding mode. Theoretical calculations with different density functionals (DFT) as well as wavefunction-based approaches were performed to elucidate the mode of action.