Resumen
Oxidative stress is defined as ?an imbalance between oxidants and antioxidants in favor of the oxidants, leading to a disruption of redox signaling and control and/or molecular damage?. This Commentary presents basic features of this global concept which has attracted interest in biology and medicine. The term ?antioxidants? in cellular defense against oxidants predominantly includes antioxidant enzymes with their substrates and coenzymes. Exogenous low-molecular-mass compounds also have a role, but this is more limited. Multiple biomarkers of damage due to oxidative stress have been identified for different molecular classes (protein, lipid, carbohydrate, and DNA), and the current state of practical aspects in health and disease is delineated.