Analytical comparision of antioxidant capacity determination methods

Antioxidants can exercise their protective properties at different stages of the oxidation process and by different mechanisms. As different testing methods provide particular, but limited information about antioxidant activity, a comparison of the methods using a single antioxidant should give information about the strength of the methods as well as about the different protective effects of the antioxidant.In this work, five methods widely employed in the evaluation of antioxidant activity, namely 2,2 ? -diphenyl-1-picrylhydrazyl (DPPH) radical scavenging method, total phenolics analysis, trolox equivalent antioxidant capacity (TEAC) assay with ABTS radical cation, cupric ion reducing capacity (CUPRAC) method and oxygen radical absorbance capacity (ORAC) method have been compared with regard to their application in the determination of antioxidant activity of ethanol and water extracts of capers (Capari spinosa L.).According to the results DPPH radical scavenging activity of water extracts of capers was forum to be slightly higher than that of ethanolic extract. On the other hand total phenolic content of water extract was found to be lower than that of ethanolic extract. According to the results of the tested methods there was a positive correlation between TEACABTS and total phenolic content whereas the correlation was negative for TEACCUPRAC and TEACORAC. In conclusion it was stated that a single antioxidant activity test would present limited information about the power of the antioxidant in question and it was emphasized that use of a combination of various methods should be used in assessing the antioxidant activities in vitro.Key words: Capers (Capari spinosa L.), DPPH, Total Phenolics, TEAC, CUPRAC,ORAC