A sensitive and ratiometric fluorescent probe for imaging cytosolic H2S generation.

As a labile molecule with a short half-life, the true concentration of H2S in biological systems is controversial. H2S-producing enzymes are mainly in the cytosol. Probes that can image cytosolic H2S in real-time and accurately are sought after. An indol–coumarin fluorophore is an ideal scaffold for mitochondrial H2S imaging. By a simple (yet rational) structural modification, CouMa was constructed with the fluorophore for cytosolic H2S detection. CouMa responded to H2S within 3 min in a ratiometric way without interference from common bio-relevant species and pH. The probe could image changes in exogenous H2S level and fluctuations in endogenous H2S generation in MCF-7 cells. The increment and depression of nitric oxide-related H2S generation in the cytosol was monitored by CouMa. It could be a powerful tool to reveal crosstalk between these two transmitters, and to image H2S generation in the cytosol. The structural-modification strategy could be useful to regulate subcellular localization. [ABSTRACT FROM AUTHOR]