Oxidative stress

Chemists and biologists typically define oxidative stress as an imbalance, particularly in biological cells, between the rate of formation and/or concentration of 'oxygen free radicals' (or 'reactive oxygen species') — potent 'oxidizing' (electron capturing) molecules — and their elimination or 'neutralization' by 'antioxidants' — 'reducing' (electron donating) molecules — the imbalance characterized by an excess of the former or a deficiency of the latter, leading to an alteration of a cell's 'redox' state towards the 'oxidized' state. The concept of oxidative stress occupies central importance importance in biology, as it applies both to physiological phenomena essential for optimal functioning of organisms and to pathophysiological phenomenona, such as cardiovascular diseases, cancer and other clinical disease states, and to considerations of the mechanisms underlying aging.

In the definition of oxidative stress given above, the terms embraced by single quotes will require further discussion before any practical understanding of the concept can emerge. Accordingly, we will try to explicate those sub-concepts in turn, and relate them in a synthesis of the concept of oxidative stress.