Quinones and Other Reactive Oxygen Species in Neurobiologic, Apoptotic, and Neurotoxic Processes

The posible role of one-electron reduction of aminochrome in the neurodegenerative process of dopaminergic system.

I was surprised by the observation that so-called neuroprotective enzymes SOD and catalase can actually promote redox cycling by o-semiquinones (fig. 1). Under different conditions and by a different chemical scheme SOD and catalase inhibit redox cycling (fig. 2). Under physiologic conditions it would seem that the latter process supersedes the former. Is this so? Are there specific conditions or substances (potential toxins or dietary cofactors) that would more strongly accelerate the sequence of figure 2 and thereby create more oxidative stress by these enzymes?

Tue Dec 15