Methods to assess free radicals and oxidative stress in biological systems

Oxidative stress results from a disruption of the prooxidant/antioxidant cellular balance and monitoring free radical status becomes an interesting challenge in animal and human nutrition. In the present work, merits and limitations of different analytical techniques (HPLC, GC‐MS, fluorometric and colourometric assays, ELISA, gel electrophoresis) for the measurement of radical mediated alterations in the cellular integrity of lipids (malondialdehyde, hydrocarbon gases, F2‐isoprostanes) proteins (protein carbonyls, 3‐nitrotyrosine) and DNA (8‐hydroxy‐2'‐deoxyguanosinè) are discussed. Besides these indirect methods, owing to the fact that free radicals are paramagnetic, electron paramagnetic resonance spectroscopy combined with spin trapping has become a valuable tool to directly assess and to better understand the mechanisms of free radical reactions. With this approach a radical that is too short‐lived to be detected, adds to a spin‐trapping agent to form a relatively long‐lived radical adduct. Information obtained from the hyperfine splitting of the spin‐trapped adduct can provide identification and quantification of the originally generated free radicals.

Key words:

• Free radicals
• Oxidative stress
• Electron paramagnetic resonance
• Lipid peroxidation
• Protein and DNA modification