Chapter 11 - Exogenous and Endogenous Mediators of Oxygen Metabolism: Alternatives for Chemical and Biological Activity

Abstract The present chapter provides the survey of the contemporary current state of art in studying the salient mechanistic alternatives of involving the bioactive mediators of oxygen metabolism in oxidative developments and draws particular attention to unresolved issues, which merit in-depth investigation. The forthcoming critical overview encompasses both chemical and biological issues, which are discussed in terms of oxidative stress. However, as the performed analysis reveals, the very term “oxidative stress” is still “ill defined,” and for comprehension of the latter phenomenon, first of all, the existing terminology needs to be revisited to reach a general agreement on definitions. The problems reviewed and analyzed herein refer to understanding the role of their numerous endogenous and exogenous mediators as prooxidant and antioxidant reactants involved in oxidation processes in vivo, merging and interconverting their chemical activities, and overlapping their functions with the other physiologically active compounds (most prominently, exhibiting hormonal activity).