FIG. 1.
The traditional concept of oxidative stress in health and disease. Originally, oxidative stress was thought to result from a global disruption in the pro-oxidant and antioxidant balance. In this view, disease was attributed to an increased burden of free radicals (thiyl radical [S•], nitric oxide radical [NO•], superoxide [O2•-], peroxynitrite [OONO–], and hydrogen peroxide) and a deficiency of endogenous antioxidants (glutathione, reduced [thiol] form [GSH], catalase, glutathione-S-transferase [GST], glutathione reductase [GR], superoxide dismutase [SOD], and glutathione peroxidase [GPX]).