Hydrogen sulfide (H₂S) is one of the important biological mediators involved in physiological and pathological processes in mammals. Recently developed H₂S donors show promising effects against several pathological processes in preclinical and early clinical studies. For example, H₂S donors have been found to be effective in the prevention of gastrointestinal ulcers during anti-inflammatory treatment. Notably, there are well-established medicines used for the treatment of a variety of diseases, whose chemical structure contains sulfur moieties and may release H₂S. Hence, the therapeutic effect of these drugs may be partly the result of the release of H₂S occurring during drug metabolism and/or the effect of these drugs on the production of endogenous hydrogen sulfide. In this work, we review data regarding sulfur drugs commonly used in clinical practice that can support the hypothesis about H₂S-dependent pharmacotherapeutic effects of these drugs.

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.