Oxidative Stress Fundamentals

Oxidative stress is an imbalance between reactive oxygen species (ROS) and an organism’s multiple antioxidant defense mechanisms (including antioxidant enzymes and small molecule oxidant scavengers). Oxidative stress may result from exposure to environmental oxidants, the metabolism of drugs or environmental toxins, and/or inadequate antioxidant defenses. It is now well recognized that oxidative stress is a critical underlying condition that plays a major role in the pathogenesis of many human diseases. ROS react with a wide range of biomolecules, including lipids, proteins and nucleic acids, and many of the adducts thus formed have been extensively characterized.

Nitrosative Stress results from production of reactive nitrogen species (RNS), especially nitric oxide, in excess of the capacity of ROS elimination mechanisms. The reaction of nitric oxide with superoxide anion produces peroxynitrite, which reacts rapidly with many molecules including cysteine and tyrosine residues on proteins resulting in the loss or alteration of function.

Free radicals are so reactive and short-lived that direct measurement is usually not possible. However, hundreds of biomarkers are known to be derived from the interaction of free radicals with biomolecules. Assays for some of these oxidative stress biomarkers, as well as assays for several of the body’s antioxidant defense mechanisms, have been widely used. Which one is best? Although there is no firm consensus, a small number of oxidized lipids, as well as byproducts of DNA and protein oxidation have withstood the test of time. Our major goal is to provide you with straightforward, reliable assays for oxidative stress biomarkers and for antioxidant capacity of biological fluids. These are listed in the table of content below.