An oxygen radical absorbance capacity-like assay that directly quantifies the antioxidant’s scavenging capacity against AAPH-derived free radicals

Scavenging rates of cyclodextrin-solubilized lipophilic antioxidants, namely catechin, epicatechin, epigallocatechin gallate, and resveratrol, against alkoxyl (RO • ) radical were measured with the use of electron paramagnetic resonance (EPR) spin-trapping method. Results indicated that the scavenging rates of catechin and resveratrol were notably dependent on the solubilizer used, i.e., native β-cyclodextrin (β-CD) or heptakis(2,6-di-O-methyl)-β-cyclodextrin (DM-β-CD). But, epicatechin and epigallocatechin gallate showed almost no dependence on the cyclodextrin used. Catechin's scavenging rate in β-CD was 66% lower than in DM-β-CD; in contrast, resveratrol in β-CD showed 45% higher rate than in DM-β-CD. Based on the reported solution-NMR structure of the inclusion complex of these antioxidants, it was concluded that the scavenging rate is decreased when the cyclodextrin cavity preferentially encapsulates the antioxidant-function bearing group, i.e., o -and p-quinolinol group in catechin and resveratrol, respectively. The depth of inclusion of the functional group determines the extent of the scavenging rate difference, suggesting that the cavity wall of the cyclodextrin acts like a barrier that hinders the approach of attacking free radicals. C 2012 Wiley Periodicals, Inc. Int J Chem Kinet 1

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“…• ) radical adduct of CYPMPO (hyperfine coupling constants: A P = 4.77 mT, A N = 1.33 mT, and A H = 1.23 mT) [1].…”

Section: Epr Measurementsmentioning

confidence: 99%

“…Acetonitrile has been shown to have no free radical scavenging capacity [1]. The stock solution was diluted with phosphate buffer containing β-CD or DM-β-CD; in final solutions, the acetonitrile content in the final solution was less than 5%.…”

Section: Sample Preparationmentioning

confidence: 99%

Cyclodextrin encapsulation of the functional group diminishes an antioxidant's free radical scavenging rates

Ishikawa

Sueishi

Endo

et al. 2012

Int J of Chemical Kinetics

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“…The fluorescence of the samples was measured at the excitation/emission wavelengths of 480 nm/514 nm in a Hitachi F-2500 spectrofluorimeter after a 15-min incubation with HOCl or ONOO -at room temperature, or after a 60-min incubation with AAPH at 37ºC. The results were analyzed in a way analogous to that presented by Kohri et al [17] by plotting ΔF/ΔF o -1 vs the concentration of the antioxidant, where ΔF is the decrease in fluorescence induced by an oxidant in the presence of a given concentration of that antioxidant, and ΔF o is the decrease in fluorescence induced by the same amount of the oxidant in the absence of an antioxidant. The initial part of this curve is linear (Robaszkiewicz et al, submitted).…”

Section: Reactivity With Abtsmentioning

confidence: 99%

The antioxidant properties of carnitine in vitro

Solarska

Lewińska

Karowicz-Bilińska

et al. 2010

Cellular and Molecular Biology Letters

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Abstract:Many of the effects of carnitine are ascribed to its antioxidant properties. The aim of this study was to evaluate the antioxidant properties of carnitine in vitro. Carnitine was found to decolorize ABTS•+ , and to protect fluorescein against bleaching induced by AAPH-derived peroxyl radicals and peroxynitrite, thiol groups against oxidation induced by hydrogen peroxide, peroxyl radicals, hypochlorite and peroxynitrite, and erythrocytes against hemolysis induced by peroxyl radicals and hypochlorite. These results show that carnitine has a direct antioxidant action against physiologically relevant oxidants.

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“…Interestingly, oxygen radicals can also be generated by photolysis of AAPH, i.e., through illumination with ultraviolet (UV) light (Kohri et al, 2009;Sueishi et al, 2010). The photolysis of AAPH efficiently generates a high quantity of oxygen radicals over a short time by illumination with UV light of adequate intensity, while no heating is required.…”

Section: Introductionmentioning

confidence: 99%

Modified Oxygen Radical Absorbance Capacity Assay that can be Implemented at Low Temperatures: A pilot study

Kohri

Fujii

2013

FSTR

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In this paper, the feasibility of a modified oxygen radical absorbance capacity assay based on fluorescence (ORAC-FL) was evaluated. In the modified ORAC-FL assay, a large quantity of radicals is generated in a short period of time by photolysis of 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH), through illumination with ultraviolet light. Importantly, no heating is required to generate the radicals, while the time required to monitor the fluorescence intensity (FI) is shortened, owing to the rapid fluorescence decay. In this study, the optimal experimental conditions for the modified assay were determined and the antioxidant capacity of two samples was evaluated at room temperature using the modified assay. Although relative ORAC values were obtained, some aspects of the modified assay require further optimization for eventual practical use.

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An oxygen radical absorbance capacity-like assay that directly quantifies the antioxidant’s scavenging capacity against AAPH-derived free radicals

Cited by 87 publications

References 27 publications

Cyclodextrin encapsulation of the functional group diminishes an antioxidant's free radical scavenging rates

Cyclodextrin encapsulation of the functional group diminishes an antioxidant's free radical scavenging rates

The antioxidant properties of carnitine in vitro

Modified Oxygen Radical Absorbance Capacity Assay that can be Implemented at Low Temperatures: A pilot study

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