A thiocoumarin based self-reporting sulfide prodrug strategy with a favorable safety profile

Abstract

H₂S as the third gasotransmitter is an important endogenous bioregulator that shows various therapeutic potentials. Herein, we present a novel thiocoumarin-based self-reporting sulfide prodrug strategy that utilizes esterase-mediated hydrolysis of thionoesters to release H₂S and provide real-time fluorescence monitoring. Our key discovery is that thionoesters can be hydrolyzed by esterases to release H₂S under physiological conditions, providing ample opportunities to design prodrugs based on ester-containing molecules. Thiocoumarin derivatives bearing a unique lactone structure offer advantages that simplify prodrug construction by substituting oxygen with sulfur in coumarin backbone and allow in-situ monitoring of H₂S release through thiocoumarin-coumarin transformation. Our prodrug candidates are demonstrated with favorable H₂S release kinetics and showed combined therapeutic effects of H₂S and coumarin, making them promising for treating cerebral infarction. Fluorescent monitoring in mouse confirmed sustained H₂S release and revealed the organ distribution, further validating the self-reporting system. Additionally, this approach that ensures therapeutic efficacy and reduces the hepatorenal toxicity of coumarin derivatives constitutes a facile prodrug strategy to overcome the toxicity of drug candidates.