Fluorogenic hydrogen sulfide (H(2)S) donors based on sulfenyl thiocarbonates enable H(2)S tracking and quantification

Hydrogen sulfide (H(2)S) is an important cellular signaling molecule that exhibits promising protective effects. Although a number of triggerable H(2)S donors have been developed, spatiotemporal feedback from H(2)S release in biological systems remains a key challenge in H(2)S donor development. Herein we report the synthesis, evaluation, and application of caged sulfenyl thiocarbonates as new fluorescent H(2)S donors. These molecules rely on thiol cleavage of sulfenyl thiocarbonates to release carbonyl sulfide (COS), which is quickly converted to H(2)S by carbonic anhydrase (CA). This approach is a new strategy in H(2)S release and does not release electrophilic byproducts common from COS-based H(2)S releasing motifs. Importantly, the release of COS/H(2)S is accompanied by the release of a fluorescent reporter, which enables the real-time tracking of H(2)S by fluorescence spectroscopy or microscopy. Dependent on the choice of fluorophore, either one or two equivalents of H(2)S can be released, thus allowing for the dynamic range of the fluorescent donors to be tuned. We demonstrate that the fluorescence response correlates directly with quantified H(2)S release and also demonstrate the live-cell compatibility of these donors. Furthermore, these fluorescent donors exhibit anti-inflammatory effects in RAW 264.7 cells, indicating their potential application as new H(2)S-releasing therapeutics. Taken together, sulfenyl thiocarbonates provide a new platform for H(2)S donation and readily enable fluorescent tracking of H(2)S delivery in complex environments.