much of the O2 supporting cellular respiration is reduced to the superoxide anion O2-.
Examples of superoxide anion
superoxide anion
These enzymes quickly detoxify highly reactive oxygen species, such as superoxide anion or hydrogen peroxide.
From the sciencedaily.com
The method has also been used for the detection of environmental toxins, such as herbicides and the determination of very low concentrations of superoxide anion in clinical samples.
From the en.wikipedia.org
Once formed, these anion free radicals reduce molecular oxygen to superoxide, and regenerate the unchanged parent compound.