Abstract
Hydrogen sulfide (H(2)S) is a ubiquitous small gaseous signaling molecule, playing an important role in many physiological processes and joining nitric oxide and carbon monoxide in the group of signaling agents termed gasotransmitters. Endogenous concentrations of H(2)S are generally low, making it difficult to discern precise biological functions. As such, probing the physiological roles of H(2)S is aided by exogenous delivery of the gas in cell and animal studies. This need for an exogenous source of H(2)S provides a unique challenge for chemists to develop chemical tools that facilitate the study of H(2)S under biological conditions. Compounds that degrade in response to a specific trigger to release H(2)S, termed H(2)S donors, include a wide variety of functional groups and delivery systems, some of which mimic the tightly controlled endogenous production in response to specific, biologically relevant conditions. This review examines a variety of H(2)S donor systems classified by their H(2)S-releasing trigger as well as their H(2)S release profiles, byproducts, and potential therapeutic applications.