Azinobis- -6-sulfonate

The total antioxidant activity of teas and tea polyphenols in aqueous phase oxidation reactions has been deterrnined using an assay based on oxidation of 2,2 -azinobis-(3-ethylbenzothiazoline-sulfonate) (ABTS) by peroxyl radicals (114—117). Black and green tea extracts (2500 ppm) were found to be 8—12 times more effective antioxidants than a 1-mAf solution of the water-soluble form of vitamin E, Trolox. The most potent antioxidants of the tea flavonoids were found to be epicatechin gallate and epigallocatechin gallate. A 1-mAf solution of these flavanols were found respectively to be 4.9 and 4.8 times more potent than a 1-mAf solution of Trolox in scavenging an ABT radical cation. 

Catechin-immobilizing polymer particles were prepared by laccase-catalyzed oxidation of catechin in the presence of amine-containing porous polymer particles. The resulting particles showed good scavenging activity toward stable free l,l-diphenyl-2-picryl-hydrazyl radical and 2,2 -azinobis(3-ethylbenzothiazoline-6-sulfonate) radical cation. These particles may be applied for packed column systems to remove radical species such as reactive oxygen closely related to various diseases. 

Radical Cation 2,2-Azinobis (3-ethylbenzothiazoline-6-sulfonate) (ABTS 1) TEAC Assay (Trolox Equivalent Antioxidant Capacity) or ABTS Assay... 

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... 

Figure 10.2. Persulfate oxidation of 2,2 -azinobis(3-ethylbenzothiazoline-6-sulfonic acid)(ABTS2).

Some years later, Miller and others (1996) described a modified TEAC assay that is able to determine the antioxidant activity of carotenoids. In the improved version, ABTS,+, the oxidant, is generated by oxidation of 2,2 -azinobis(3-ethylbenzothiazoline-6-sulfonic acid)(ABTS2 ) with manganese dioxide. A similar approach was described by Re and others (1999) in which ABTS was oxidized with potassium persulfate (Fig. 10.2), this version of the TEAC assay is applicable to both water soluble and lipophilic antioxidants (Re and others 1999 Pellegrini and others 1999). 

Nilsson J, Pillai D, Onning G, Persson C, Nilsson A and Akesson B. 2005. Comparison of the 2,2 -azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) and ferric reducing antioxidant power (FRAP) methods to asses the total antioxidant capacity in extracts of fruit and vegetables. Mol Nutr Food Res 49(3) 239-246. 

Pellegrini N, Re R, Yang M and Rice-Evans C. 1999. Screening of dietary carotenoids and carotenoid-rich fruit extracts for antioxidant activities applying 2,2 -azinobis(3-ethylenebenzothiazohne-6-sulfonic acid) radical cation decolorization assay. Methods Enzymol 299 379-389. 

Enzyme Assays. Laccase activity was determined by oxidation of 2,2-azinobis-(3-ethylbenzthiazoline-6-sulfonate) (ABTS). The reaction of suitably diluted enzyme was determined at 420 nm in the presence of 0.03% ABTS and 100 mM sodium acetate buffer, pH 5.0. The extinction coefficient of ABTS is 420 = 3.6 x 104 M-1 cm-1 (26). 

Azadigermirane, photooxygenation, 825-6 2,2 -Azinobis(3-ethylbenzothiazoline)-6-sulfonate (ABTS)... 

Substrate solution for HRP 1 mM 2,2 azinobis 3-ethylbenzthiazoline-6 sulfonic acid (ABTS) (Sigma, St. Louis, MO) in 0.1M sodium acetate, pH 5 0. Add 1 pL of 30% hydrogen peroxide/1 mL of ABTS solution just before use. Discard any old ABTS stocks that have a noticeable green color when dissolved in the absence of hydrogen peroxide... 

Fig. 5. A popular chromogenic substrate for assays of TAC, 2,2/-azinobis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS).

ABTS, 2,2 -Azinobis(3-ethylbenzthiazoline-6-sulfonic acid) FRAP, ferric-reducing activity of plasma DPPH, l,l-diphenyl-2-picrazyl DMPI), Y,/V-dimethyl-o-phenylenediamine. 

A10. Aliaga, C., and Lissi, E. A., Reaction of 2,2 -azinobis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS +) derived radicals with hydroperoxides. Kinetics and mechanism. Can. J. Chem. 78, 1052-1059 (1998). 

C31. Collins, P. J., Dobson, A. D. W., and Field, J. A., Reduction of the 2,2 -azinobis (3-ethylbenzthiazolidine-6-sulfonate) cation radical by physiological organic acids in the absence and presence of manganese. Appl. Env. Microbiol. 64, 2026-2031 (1998). 

W13. Wolfenden, B. S., and Wilson, R. L., Radical-cations as reference chromogens in kinetic studies of one electron transfer reactions Pulse radiolysis studies of 2,2 -azinobis-(3-ethylbenzthiazoline-6-sulfonate). J. Chem. Soc. Perkin Trans. 2, 805-812 (1982). 

ABTS trapping capacity. 2,2 -Azinobis-3-ethyl-thiazoline-6-sulfonate. Useful under hydrophilic and lipophilic conditions ... 

Another efficient method is the electrochemical oxidation of NADH at 0.585 V vs Ag/AgCl by means of ABTS2- (2,2,-azinobis(3-ethylbenzothiazoline-6-sulfonate)) as an electron transfer mediator [96]. Due to the unusual stability of the radical cation ABTS, the pair ABTS2 /ABTS is a useful mediator for application in large-scale synthesis even under basic conditions. Basic conditions are favorable for dehydrogenase catalyzed reactions. This electrochemical system for the oxidation of NADH using ABTS2 as mediator was successfully coupled with HLADH to catalyze the oxidation of a meso-diol (ws >-3,4-dihydroxymethylcyclohex-l-ene) to a chiral lactone ((3aA, 7aS )-3a,4,7,7a-tetrahydro-3//-isobenzofurane- l-one) with a yield of 93.5% and ee >99.5% (Fig. 18). 

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