Looking Beyond the Traditional Idea of Glutathione Peroxidase Mimics as Antioxidants
Selenium is an essential microelement for mammals as well as bacteria and several studies have explored its biological activity, discovering a series of selenium-containing enzymes involved in the maintenance of the redox equilibrium in the cells. Among them, glutathione peroxidase (GPx) is nowadays the most studied selenoenzyme and the redox mechanism that leads to the peroxide reduction in the presence of a reductive thiol is well characterized and proved. Studies on small organoselenium GPx-like molecules having antioxidant activity has enabled the collection of precious information to understand the interaction of organoselenium compounds in the maintenance of life. Now, 200 years after the discovery of selenium, we have the opportunity to re-consider the redox behavior of some organoselenium derivatives as a new bullet for specific targets. In this chapter, after an exploration of the different mechanisms involving organoselenium derivatives in the catalytic reduction of peroxides using different thiols as cofactors, we focus our attention on the most recent examples that have contributed to changing the paradigm of organoselenium compounds just as antioxidants. We highlight the possibility of targeting some compounds toward free biologically relevant thiols and zinc finger domain of proteins, or using the GPx-like activity as a redox probe in some living systems.