The oxygen paradox

Abstract

Even essential for the aerobic organisms survive and cellular respiration through the redox energogen reaction, the oxygen seems to be not only a "life support" but also a start point for a type of tissular injuries recognized with the generic term of "oxidative stress". In fact, if the most part of the cellular oxygen is normally metabolized through a citochromoxidase enzyme, 2-5% of it escape from this bivalent reduction and choose the monovalent one, resulting in toxic free radicals. Their implication is well known in some physiological but also pathological processes. So, the last two decades data justify the idea that oxygen role is as complex as paradoxical.