Trolox

One vitamin E analogue, TROLOX, inhibits radiation-induced apoptosis in murine thymocytes (26). Chicks given vitamin E prior to exposure to a sublethal dose (2.25 Gy (225 rad)) of y-radiation demonstrate a more rapid recovery from damage to the thymus (100). 

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. 

Methyl-substituted primary alcohols can be separated after derivatization with [6-methoxy-2,5,7,8-tetramethylchromane-2-carboxylic acid] (Trolox M methyl ether) [13] while sec.- and tert.-alcohols are derivatized with 2-dimethylamino-l,3-dimethyl-octahydro-lf/-l,3,2-benzodiazaphosphole [14] (Eig. 7-5). 

Fig. 3. a) First order plot of oxygen uptake in the Methylene-blue (MB)-sensitized photooxidation of GA 8.4 pM and 1.3 mM histidine (control) in phosphate buffer pH 7. b) Percentage radical scavenging activity for the control molecule Trolox and GA at pH 7.4 in phosphate buffer 10 mM (hydroxyl radical) and pH 10 in sodium carbonate buffer 50 mM (anion superoxide radical). 

Gliszczyhska-Swigl, A. (2006). Antioxidant activity of water soluble vitamins in the TEAC (trolox equivalent antioxidant capacity) and the FRAP (ferric reducing antioxidant power) assays. Food Chemistry, Vol.96, No.l, (May 2006), pp. 131-136, ISSN 0308-8146. 

Under aqueous conditions, flavonoids and their glycosides will also reduce oxidants other than peroxyl radicals and may have a role in protecting membranal systems against pro-oxidants such as metal ions and activated oxygen species in the aqueous phase. Rate constants for reduction of superoxide anion show flavonoids to be more efficient than the water-soluble vitamin E analogue trolox (Jovanovic et al, 1994), see Table 16.1. 

For aqueous solutions, ascorbate can be included in the hierarchy, while a-tocopherol has to be replaced by its water-soluble analogue trolox, which is often assumed to have the same standard reduction potential. The ordering of the antioxidants based on the two different determinations of E in water is rather similar, and it should be noted that ascorbate is the antioxidant which will regenerate the other antioxidants, with the ascorbate itself ending up being oxidised. In contrast to what was observed for DMF, the ordering in water predicts that quercetin could regenerate a-tocopherol from its oxidised form. 

Larsen E, Abendroth J, Partali V, Schulz B, Sliwka HR, and Quartey EGK. 1998. Combination of vitamin E with a carotenoid a-Tocopherol and trolox linked to (3-apo-8 -carotenoic acid. Chemistry—A European Journal 4(1) 113-117. 

Lerfall J. 2002. Syntetisk kombinasjon av P-apo-8 -karotensyre, vitamin C, EPA, trolox og selenafettsyre, Master thesis, Norwegian University of Science and Technology, Trondheim, Norway. 

From Table 14.6 it can be seen that, with the exception of astaxanthin (ASTA), the rate constants for the electron transfer reactions decrease for each carotenoid in the order 9-phenanthryl peroxyl > 1-naphthyl peroxyl > 2-naphthyl peroxyl. This order of reactivity should be related to the reduction potentials of the radicals, with 9-phenanthryl peroxyl having the highest reduction potential. The same order of reactivity for these three arylperoxyl radicals reacting with Trolox was shown by Neta and coworkers (Alfassi et al. 1995). The reactivities of all the carotenoids studied are similar... 

The bimolecular rate constants were determined (Burke 2001) for the repair of carotenoid radical cations by trolox, ascorbic, ferrulic, and uric acids from the pulse radiolysis studies of carotenoids in aqueous micellar solutions (see Table 14.10). 

As can be seen, all the water-soluble compounds are capable of quenching CAR + efficiently, with rate constants of the order of 106,107, and 108 M 1 s 1 for ferrulic acid, both ascorbic and uric acids, and Trolox, respectively. 

CAR + max(nm) Ascorbic Acid Trolox Ferrulic Acid Uric Acid... 

Regarding antioxidants, the parameter total dietary antioxidant capacity (TDAC) can be taken to reflect antioxidant intake it is defined as the antioxidant capacity of all plant foods and beverages (alcoholic and nonalcoholic) consumed daily in a diet and may represent the amount of antioxidant units (Trolox equivalents) present daily in the human gut (Saura-Calixto and Goni 2006). 

TDAC in the Spanish diet has been estimated at 3,500 pimol Trolox equivalents by the ABTS method. The contribution of each specific food to the TDAC was dependent on both food intake and food antioxidant capacity. The largest contributors to the TDAC were beverages (about 68%) and fruits and vegetables (about 20%). 

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... 

Another assay that is very similar to the ABTS assay is the AGV-dimethyl-p-phenylenediamine (DMPD assay). In the presence of a suitable oxidant solution at an acidic pH, DMPD is converted to a stable and colored DMPD radical cation (DMPD +). Antioxidants capable of transferring a hydrogen atom to the radical cause the decol-orization of the solution, which is spectrophotometrically measured at 505 nm. The reaction is stable, and the endpoint is taken to be the measure of antioxidant efficiency. Antioxidant ability is expressed as Trolox equivalents using a calibration curve plotted with different amounts of Trolox (Fogliano and others 1999). This method is used to measure hydrophilic compounds. The presence of organic acids, especially citric acid, in some extracts may interfere with the DMPD assay, and so this assay should be used with caution in those extracts rich in organic acids (Gil and others 2000). 

A typical time course of PCL with luminol as the photosensitizer is shown in Figure 5, as blank. The presence of a water-soluble antioxidant leads to dose-dependent temporary inhibition of PCL. ACW (antioxidant capacity of water-soluble compounds) represents the effect of human blood plasma (2 p.L) on PCL all tested antioxidants, such as ascorbic acid, uric acid, Trolox, taurine, bilirubin, ceruloplasmin, etc., produced the same effects. 

Basic procedure (ACL kit) Mix 2400 pL of ACL reagent 1 (diluter) with 100 pL of ACL reagent 2 (buffer) and 25 pL of photosensitizer reagent (luminol based). Start measurement after brief vortexing. Assayed solution (lipid extract) is added before addition of photosensitizer reagent. Volume of ACL reagent 1 is reduced by the volume of assayed solution. Standard substance a-tocopherol or Trolox. Duration of measurement 1 min. Measured parameter integral (area under the kinetic curve of PCL). 

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