Evaluation of Antioxidants Activity through the Chemical Assay

Recently, studies on natural source antioxidants have become increasingly active in various fields. Among analytical methods for antioxidant activity, the DPPH, ABTS and TBA assays had become quite popular in natural antioxidant studies. One of the reasons is that these methods are simple and highly sensitive. Especially DPPH and ABTS assays are based on the theory that a hydrogen donor is an antioxidant. The antioxidant effect can be easily evaluated by following the decrease of specific UV absorption and the results are usually expressed in terms of Trolox equivalent antioxidant capacity (TEAC). The TBA assay has been commonly used to measure lipid oxidation in some foods and biological systems. Because the colored complex is formed by the TBA-malonaldehyde interaction, the TBA value can be evaluated by UV spectrophotometer or HPLC. However, the TBA-malonaldehyde complex is very unstable and often either is not detected in many oxidized lipids or is a minor secondary oxidation product. Because of these defects, numerous studies are going on.