ON THE GENERATION OF THE HYDROXYLATION AGENT FROM SUPEROXIDE RADICAL. CAN THE HABER–WEISS REACTION BE THE SOURCE OF OH RADICALS?

Abstract

Abstract— In many biological systems, the role of O 2 ‐ in hydroxylation and toxic processes was assumed to be due to the formation of OH radicals. The Haber‐Weiss reaction (Haber and Weiss, 1934)—(H 2 O 2 + O 2 ‐ → OH + OH ‐ + O 2 ) was suggested as the origin of this activity. In this study it is shown that this reaction pathway is too slow, and that OH is probably formed from the reaction of complexed superoxide with H 2 O 2 or/and from the reduction of Fe(III), bound to biological compounds, by O 2 ‐ ; the reduced Fe(II) can then react with H 2 O 2 as a Fenton reagent, to yield OH. It is also shown that singlet oxygen cannot be formed in these biological systems neither from the dismutation of OJ nor from the reaction of O 2 ‐ with OH. Singlet oxygen may be formed from the reduction of metal complexes by O 2 ‐ .