Recommendations for Determining Antioxidant Activity to Study Redox Status and Plant Stress

Antioxidant activity is a very useful parameter for characterizing the potential of biological samples to scavenge reactive oxygen and nitrogen species and other dangerous free radicals in specific reaction media. This parameter has been extensively used in fields such as phytochemistry, food chemistry, food science and technology, human and animal physiology, dietetics and nutrition. It has also been used in plant physiology, but to a lesser extent. Several methodological approaches for measuring antioxidative capacity in plant extracts are presented and the advantages and disadvantages of the most relevant methods from a physiological point of view are discussed. The discrimination between hydrophilic and lipophilic antioxidant activities is very important for identifying the specific antioxidants present in plant samples. The plant redox status of different tissues and its relationship with plant stress situations can be studied by reference to the antioxidant activity, which is an interesting parameter that permits us to investigate the overall antioxidative potential, its distribution, its evolution and its adaptation to different environmental situations. Possible future applications are also presented. _____________________________________________________________________________________________________________