Antioxidant activity applying an improved ABTS radical cation decolorization assay

Free Radic Biol Med. 1999 May;26(9-10):1231-7. doi: 10.1016/s0891-5849(98)00315-3.


A method for the screening of antioxidant activity is reported as a decolorization assay applicable to both lipophilic and hydrophilic antioxidants, including flavonoids, hydroxycinnamates, carotenoids, and plasma antioxidants. The pre-formed radical monocation of 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS*+) is generated by oxidation of ABTS with potassium persulfate and is reduced in the presence of such hydrogen-donating antioxidants. The influences of both the concentration of antioxidant and duration of reaction on the inhibition of the radical cation absorption are taken into account when determining the antioxidant activity. This assay clearly improves the original TEAC assay (the ferryl myoglobin/ABTS assay) for the determination of antioxidant activity in a number of ways. First, the chemistry involves the direct generation of the ABTS radical monocation with no involvement of an intermediary radical. Second, it is a decolorization assay; thus the radical cation is pre-formed prior to addition of antioxidant test systems, rather than the generation of the radical taking place continually in the presence of the antioxidant. Hence the results obtained with the improved system may not always be directly comparable with those obtained using the original TEAC assay. Third, it is applicable to both aqueous and lipophilic systems.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antioxidants / pharmacology*
  • Benzothiazoles
  • Cations
  • Color
  • Drug Evaluation, Preclinical / methods*
  • Ethanol
  • Evaluation Studies as Topic
  • Free Radicals
  • In Vitro Techniques
  • Indicators and Reagents*
  • Sulfonic Acids*


  • Antioxidants
  • Benzothiazoles
  • Cations
  • Free Radicals
  • Indicators and Reagents
  • Sulfonic Acids
  • 2,2'-azino-di-(3-ethylbenzothiazoline)-6-sulfonic acid
  • Ethanol