Free radical biology - terminology and critical thinking

What is an antioxidant? Can one, at a cellular level, speak of direct and indirect antioxidants? Can oxidative stress be quantified and characterized? What are the oxidant species that may have regulatory functions in a cell? Since the above concepts have become of frequent use in all Journals it may be appropriate if some critical thinking outlined in this review could become available to a broad public. (C) 2004 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.