Reactive xygen Species Double-faced Yanus in Living Organisms

Daniela Gerova, Trifon Chervenkov, Bistra Galunska


The molecular oxygen is vital for the existence of all aerobic organisms. The paradox is that at certain conditions, by forming reactive oxygen species (ROS) in vivo, it can be a lethal toxin. In living organisms ROS play dual role. When produced at low physiological concentration they are important intracellular regulators and protectors against bacterial infection. ROS nonspecifically oxidize and impair a number of important biomacromolecules. This could lead to change or loss of function of cellular structures at high nonphysiological ROS concentration.

In the course of the evolution antioxidant mechanisms for protection from the harmful effects of ROS has evolved, which lower the level of ROS and sustain the balance between the processes that produce ROS and those eliminating them. The impairment of this balance and the ensuing cellular and tissue damage are defined as oxidative stress. In the pathogenesis of majority diseases such as cardiovascular, diabetes mellitus, neurodegenerative, autoimmune, inflammatory and neoplastic, the oxidative stress is present.