Thiosulfonate-Based Targeted Covalent Cruzipain Inhibitors with Enhanced Bioactivity Translation for Antichagasic Therapy

Chagas disease remains a neglected tropical disease with limited therapeutic options and a pressing need for new antichagasic agents. In this context, Cruzipain (CZP), the main cysteine protease of T. cruzi, has been validated as a promising target for reversible targeted covalent inhibitors (TCIs). Building upon our previous research, this study reports phenyl thiosulfonate (TSO)-based TCIs, designed to optimize enzymatic performance and enhance bioactivity translation from in vitro CZP inhibition to T. cruzi-infected cell models. Among ten potent phenyl TSO TCIs, TSO-13 exhibited high CZP inhibitory potency, selectivity over human cathepsin L, and excellent bioactivity translation in parasite-infected cells. Computational studies highlighted the dual benefit of the TSO moiety in combining optimal reactivity with enhanced encounter complexes’ stability. Overall, these findings position triazole-based phenyl TSO derivatives as promising candidates for rational CZP inhibitor design, representing a valuable contribution for developing innovative antichagasic agents.