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

Ample evidence suggests that H(2)S 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 H(2)S 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 H(2)S detection, 4-methyl-2-oxo-2H-chromen-7-yl 5-azidopentanoate (1). The design of 1 is based on combination of two strategies for H(2)S detection, i.e., reduction of an azido group to an amine in the presence of H(2)S and intramolecular lactamization. Finally, we measured salivary H(2)S concentration in healthy, 18–40-year-old volunteers immediately after obtaining specimens. The newly developed self-immolative coumarin-based fluorescence probe (C(15)H(15)N(3)O(4)) showed high sensitivity to H(2)S detection in both sodium phosphate buffer at physiological pH and in saliva. Salivary H(2)S concentration in healthy volunteers was within a range of 1.641–7.124 μM.