...aerobic organisms possess an antioxidant defense system to protect against ROS-mediated injury. A broad definition of an antioxidant is "any substance that,...of an oxidizable substrate, significantly delays or prevents oxidation of that substrate" [37-38]. Oxidizable substrates include DNA, lipids, proteins,...

...chain-breaking compounds, Halliwell and Gutteridge (11), taking a much broader view, define an antioxidant as "any substance that, when present at low concentrations...significantly delays or inhibits oxidation of that substrate." To be effective against free-radical-mediated cell disturbances, the antioxidants or free-radical scavengers...

...brought about by antioxidants. In a theoretical sense, an antioxidant can be defined as "any substrate that, when present at low concentrations compared to those of an oxidizable substrate, significantly inhibits or delays oxidation of that substrate."67 Our major objective is to review the data concerning...

...of the material or substrate under study. Halliwell and Gutteridge (1989) defined an antioxidant as "any substance that, when present at low concentrations...significantly delays or inhibits oxidation of that substrate". However, when considering pharmaceutically relevant antioxidants, one may also need to include compounds...

...of nitrosothiols and nitrotyrosine residues as a result of RNS attack (Darley-Usmar et al., 1995). An antioxidant is "any substance that, when present...of an oxidizable substrate, significantly delays or prevents oxidation of that substrate" (Halliwell, 1990). "Oxidizable substrates" include the DNA, lipids,...

...deoxyribonucleic acid (DNA) as well as lipids, and so the author has introduced a broader definition: an antioxidant is any substance that, when present...of an oxidizable substrate, significantly delays or prevents oxidation of that substrate (4,5). The term oxidizable substrate covers almost everything...

...natural defenses used by the body to combat ROS and RNS attack. Halliwell has defined an antioxidant as "any substance that, when present at low concentrations compared to those of an oxidizable substrate (eg, lipids, proteins and DNA), significantly delays or prevents oxidation of that substrate" (see...

...proteins, DNA and other molecules in addition to lipids. Hence one broader definition is (Halliwell, 1990): "An antioxidant is any substance that, when present...of an oxidizable substrate, significantly delays or prevents oxidation of that substrate." The term "oxidizable substrate" includes everything found in...

...levels of 4-hydroxynonenal and in cell cultures. ANTIOXIDANTS Halliwell has defined an antioxidant as "any substance that, when present at low concentrations...of an oxidizable substrate, significantly delays or prevents oxidation of that substrate" (Halliwell (1994)). This definition therefore not only includes...

...experiments. A definition of practical relevance for antioxidants was proposed by Halliwell and Gutteridge7 : "any substance that, when present at low concentrations compared to those of an oxidisable substrate, significantly delays or prevents oxidation of that substrate." This means that...