Enzymatic antioxidant that removes the potentially toxic superoxide ion (\(\ce{O2^{-}}\)) by disproportionating it to \(\ce{O2}\) and hydrogen peroxide (\(\ce{H2O2}\)).
Source: PAC, 2007, 79, 1153. (Glossary of terms used in toxicology, 2nd edition (IUPAC Recommendations 2007)) on page 1316 [Terms] [Paper]