Trolox equivalent antioxidant capacity TEAC

The Trolox equivalent antioxidant capacity (TEAC) assay was reported first by Miller and others (1993) and Rice-Evans and Miller (1994). They used the peroxidase activity of metmyoglobin to oxidize 2,2 -azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) in the presence of hydrogen peroxide. The TEAC assay is based on the... 

In vitro Antioxidant capacity was measured by the method of Trolox equivalent antioxidative capacity (TEAC) [12]. The TEAC assay used 20 pL of the extract sample mixed with a 980 pL solution of ABTS + [2.2 -azobis-(3-ethylenebenzothia-zohne-6-srrlfonic) acid], the decolorization of ABTS ", which is a long-life radical cation and bine-green chromophore, measrrred at 734 nm. Results are expressed as millimoles of Trolox equivalent per kilograms of fresh weight. 

Trolox Equivalent Antioxidant Capacity (TEAC) assay... 

Correlate the decrease observed in a dose-response curve with a standard antioxidant (e.g., trolox, ascorbic acid), expressing the antioxidant activity as equivalents of standard antioxidant, a well-established parameter in this respect being Trolox Equivalent Antioxidant Capacity (TEAC). ... 

Flavonoids as antioxidants have been reviewed several times 45s including an outline of many claims to their beneficial health effects . Due to their complex structures and different classes (eight thousand different compounds are known ), researchers often resorted to qualitative screening methods to evaluate their antioxidant potentials in mixed aqueous/lipid phases. For example, the so-called Trolox equivalent antioxidant capacity (TEAC), the concentration of Trolox with equivalent antioxidant activity of a 1 mM concentration of the substrate, is frequently used in heterogeneous systems. Unfortunately, this can be an unreliable measure of the activity of the substance, especially if initiation is also carried out in the aqueous phase. Nevertheless, there have been some efforts made to evaluate antioxidant activities of specific flavonoids using more quantitative methods in heterogeneous systems in order to mimic natural environments. A few examples are cited below to illustrate some approaches to determine flavonoid activities in micelles or lipid membranes. 

The xanthone compounds l,3,5-trihydroxy-2-(2, 2 -dimethyl-4 -isopropenyl) cyclopentanylxanthone, 5-0-demethyl-6-deoxypaxanthonin, and 5-0-de-methylpaxanthonin, as well as 3,5-dihydroxybenzophenone-4-/8-D-glucoside and 3-geranyl- l-(3-methylbutanoyl)phloroglucinol isolated from the leaves of Hypericum styphelioides, were evaluated for their antioxidative properties in Trolox equivalent antioxidant capacity (TEAC) and chemiluminescence (CL) assays. 

Siriwardhana and Shahidi [33] evaluated the Trolox equivalents antioxidant capacity (TEAC) of almond and its by-product extracts and found that ethanolic extracts, at the same concentration the TEAC values, followed the order of brown skin > green shell cover > whole seed (kernel). Values of brown skin and green shell cover extracts were 12.6- and 9.8-fold higher than that of whole seed extract, respectively. Alasalvar et al. [30] observed that hazelnut kernel and its green leafy cover extracts from 80% (v/v) ethanol were characterized as having significantly lower (P < 0.05) total antioxidant activity compared to those of extracts obtained from 80% (v/v) acetone. 

Over the years, a variety of assays to measure the total antioxidant capacity of pure substances, biological fluids, food extracts, and beverages have been developed. Among the most commonly used are the Trolox equivalent antioxidant capacity (TEAC), oxygen radical absorbance capacity (ORAC), and ferric reducing ability of plasma (FRAP) assays. 

TABLE 29.8 Trolox Equivalent Antioxidant Capacity (TEAC) of the Food Samples by Spectrophotometric and Electrochemical Techniques Using the Scavenging DPPH Method... 

Berg, R., G. R. M. M. Haenen, H. Berg et al. 1999. Applicability of an improved Trolox equivalent antioxidant capacity (TEAC) assay for evaluation of antioxidant capacity measurements of mixtures. Food Chem. 66 511-517. 

Trolox equivalent antioxidant capacity (TEAC) spectrophotometric assay was used to estimate antioxidant capacity (Miller et al., 1993 Re et al., 1999) of edible vegetable oils. This method relies on the capacity of antioxidants to scavenge a non-biological radical, 2,2 -azinobis(3-ethylbenzothiazoline-6-sulphonate) (ABTS) (Figure 8). 

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