Pharmacology of organoselenium compounds: Emphasis on puzzling mechanistic switching from their glutathione peroxidase mimic in vivo

Organoselenium compounds are a new class of emerging potent antioxidants. Basically, their rational design and synthesis was aimed at mimicking the native glutathione peroxidase enzyme in their reduction of hydroperoxides at the expense of the ubiquitous antioxidant, glutathione. In this review, emphasis was focused on the seemingly antagonistic mechanisms employed by organoseleniums under in vitro and in vivo conditions. Summarily, in vitro evidences clearly demonstrate that the pharmacological effect of organoseleniums strictly depends on their GPx mimic. However, these selenium based compounds evoke an increase in the level of endogenous thiols suggesting a possible switch in their glutathione peroxidase mimic under in vivo conditions. Apparently, this mechanistic switch is puzzling and requires concerted efforts to unravel.