WSP-5

WSP-5 (CAS No.: 1593024-78-2) is a hydrogen sulfide-selective, reaction-based fluorescent probe widely used for the sensitive detection and visualization of endogenous and exogenous H2S in biological systems. Functionally categorized as a turn-on fluorogenic sensor, WSP-5 operates through a nucleophilic substitution–cyclization mechanism in which H2S selectively reacts with the probe to release a fluorescent signal with excitation and emission maxima at approximately 502 and 525 nm, respectively, enabling real-time monitoring of H2S dynamics. Hydrogen sulfide is an important gaseous signaling molecule implicated in multiple physiological and pathological processes, including regulation of immune, neuronal, cardiovascular, and pulmonary functions, and WSP-5 provides a robust tool for interrogating these pathways at the cellular level. Compared with earlier-generation probes such as WSP-1, WSP-5 exhibits markedly faster fluorescence activation kinetics and improved sensitivity, making it particularly suitable for detecting low-abundance or rapidly fluctuating H2S levels. It has been applied in live-cell imaging, including studies of H2S release from donor compounds and accumulation in cancer cell models such as glioma, supporting its utility in disease-relevant research and drug discovery workflows. As a chemical probe rather than a therapeutic agent, WSP-5 does not target proteins directly but instead enables the study of H2S-associated signaling networks, and experimental concentrations are typically optimized based on assay conditions, cell type, and imaging requirements.