Salivary Hydrogen Sulfide Measured with a New Highly Sensitive Self-Immolative Coumarin-Based Fluorescent Probe

Ample evidence suggests that H2S is an important biological mediator, produced by endogenous enzymes and microbiota. So far, several techniques including colorimetric methods, electrochemical analysis and sulfide precipitation have been developed for H2S detection. These methods provide sensitive detection, however, they are destructive for tissues and require tedious sequences of preparation steps for the analyzed samples. Here, we report synthesis of a new fluorescent probe for H2S detection, 4-methyl-2-oxo-2H-chromen-7-yl 5-azidopentanoate (1). The design of 1 is based on combination of two strategies for H2S detection, i.e., reduction of an azido group to an amine in the presence of H2S and intramolecular lactamization. Finally, we measured salivary H2S concentration in healthy, 18–40-year-old volunteers immediately after obtaining specimens. The newly developed self-immolative coumarin-based fluorescence probe (C15H15N3O4) showed high sensitivity to H2S detection in both sodium phosphate buffer at physiological pH and in saliva. Salivary H2S concentration in healthy volunteers was within a range of 1.641–7.124 μM