Details

Autor(en) / Beteiligte

• Cano, Antonio
• Hernández-Ruíz, Josefa
• García-Cánovas, Francisco
• Acosta, Manuel
• Arnao, Marino B.

Titel

An end-point method for estimation of the total antioxidant activity in plant material

Ist Teil von

• Phytochemical analysis, 1998-07, Vol.9 (4), p.196-202

Ort / Verlag

Chichester, UK: John Wiley & Sons, Ltd

Erscheinungsjahr

1998

Link zum Volltext

Quelle

Wiley Online Library - AutoHoldings Journals

Beschreibungen/Notizen

• The 2,2′‐azino‐bis‐(3‐ethylbenzthiazoline‐6‐sulphonic acid) (ABTS) radical can be generated by the enzymatic system formed by hydrogen peroxide and horseradish peroxidase. This ABTS radical (ABTS·+), a chromogen, is stable at room temperature but is unstable above 35°C and/or at pH values of above 7.5. Nevertheless, the most important factor in its stability is the ABTS/ABTS·+ concentration ratio in the medium. The radical reacts with the antioxidant, L‐ascorbic acid, with a high rate constant, the stoichiometry of the reaction being 1 mol of L‐ascorbic acid per 2 mol of ABTS·+ reduced. Based on these considerations, a spectrophotometric end‐point method has been developed to evaluate L‐ascorbic acid in aqueous media, and this represents an improvement over the lag‐method previously reported. Under optimal conditions of temperature, pH and reagent concentration, the end‐point method was capable of determining L‐ascorbic acid with a limit of quantification of 0.38 nmol. In the assay described here, this ability is used to evaluate the total antioxidant activity of commercial citrus juices, in which ascorbic acid is a principal component. In our opinion this procedure can quickly provide useful information on the antioxidant content of foods and plant extracts. © 1998 John Wiley & Sons, Ltd.