Magnetite Fe3 O4 Has no Intrinsic Peroxidase Activity, and Is Probably not Involved in Alzheimer's Oxidative Stress.

Despite stated in some highly cited articles, magnetite is devoided of peroxidase activity. In fact, this very stable mixed valence FeII O⋅FeIII 2 O3 complex is not catalytically competent to oxidize standard peroxidase substrates, especially at the biologically relevant pH value of 7.4. In addition, magnetite whose deleterious redox activity has been suspected in Alzheimer's disease brain damages, does not significantly interact with amyloid peptide Aβ in vitro, and is not able to induce, either in the presence or absence of Aβ, the reductive activation of dioxygen, the first step of an oxidative stress. In fact, this highly insoluble mineral iron derivative is probably not involved in the oxidative damage of brain neurons of patients with AD.