Recent Developments On Activatable Turn-On Fluorogenic Donors of Hydrogen Sulfide (H 2 S).

Hydrogen sulfide (H 2 S) is considered the third member of the gasotransmitter family, along with nitric oxide (NO) and carbon monoxide (CO). Besides its role in physiological and pathophysiological conditions, the promising therapeutic potential of this small-molecule makes it advantageous for various pharmaceutical applications. The endogenous production of H 2 S at a lower concentration is crucial in maintaining redox balance and cellular homeostasis, and the dysregulation leads to various disease states. In the event of H 2 S deficiency, the exogenous donation of H 2 S could help maintain the optimal cellular concentration of H 2 S and cellular homeostasis. Over the last several years, researchers have developed numerous small-molecule non-fluorogenic organosulfur compounds as H 2 S donors and investigated their pharmacological potentials. However, reports on stimuli-responsive turn-on fluorogenic donors of H 2 S have appeared recently. Interestingly, the fluorogenic H 2 S donors offer additional advantages with the non-invasive real-time monitoring of the H 2 S release utilizing the simultaneous turn-on fluorogenic processes. The review summarizes the recent developments in turn-on fluorogenic donors of H 2 S and the potential biological applications that have developed over the years.