Antioxidant activity assay based on laccase-generated radicals |
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Authors: | Endry Nugroho Prasetyo Tukayi Kudanga Walter Steiner Michael Murkovic Gibson S Nyanhongo Georg M Guebitz |
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Institution: | (1) Department of Environmental Biotechnology, Graz University of Technology, Petersgasse 12/1, 8010 Graz, Austria;(2) Institute of Biotechnology and Bioprocess Engineering, Graz University of Technology, Petersgasse 12/1, 8010 Graz, Austria;(3) Institute of Food Chemistry and Technology, Graz University of Technology, Petersgasse 12/1, 8010 Graz, Austria |
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Abstract: | A novel antioxidant activity assay was developed using laccase-oxidized phenolics. In a three-step approach, phenolic compounds
were first oxidized by laccase. Laccase was then inhibited using 80% (v/v) methanol which also stabilized the oxidized phenolics
which were then used to measure antioxidant activities of ascorbic acid and Trolox. From a number of laccase-oxidized phenolics
screened for potential use in the measurement of antioxidant activities, syringaldazine emerged the best, giving results comparable
to the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical, which is currently used in conventional methods. Like DPPH radicals,
two moles of stoichiometric oxidized syringaldazine were reduced by one mole of either ascorbic acid or Trolox. For the first
time we show that antioxidant activity can be correlated to oxygen consumption by laccase. Reduction of one molecule of oxygen
corresponded to oxidation of four molecules of syringaldazine which in turn is reduced by two molecules of Trolox or ascorbic
acid. This study therefore demonstrates the great potential of using laccase-oxidized syringaldazine for the measurement of
antioxidant activity. |
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Keywords: | Laccase-oxidized phenolics Antioxidant assay Syringaldazine |
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