Extending Applicability of the Oxygen Radical Absorbance Capacity (ORAC−Fluorescein) Assay

Abstract

The ORAC-fluorescein (ORAC-FL) method recently validated using automatic liquid handling systems has now been adapted to manual handling and using a conventional fluorescence microplate reader. As calculated for Trolox, the precision of the method was <3.0, expressed as percent coefficient of variation. The accuracy of the method was <2.3, expressed as percent variation of the mean. The detection and quantification limits were those corresponding to 0.5- and 1-microM Trolox standard solutions, respectively. The method has been applied to 10 pure compounds (benzoic and cinnamic acids and aldehydes, flavonoids, and butylated hydroxyanisole), to 30 white, rose, and bottled- and oak-aged red wines, and to 7 commercial dietary antioxidant supplements. All samples exhibited a good linear response with concentration. As seen by other methodologies, the chemical structure of a compound determines its antioxidant activity (ORAC-FL value). Of particular interest were the results with oak-aged red wines from different vintages (1989-2002) that confirm influence of vintage, but not origin of the oak, in the antioxidant activity of wines from the same variety. Dietary antioxidant supplements presented a great variability (170-fold difference) in their antioxidant potency. This work proves applicability of the ORAC-FL assay in evaluating the antioxidant activity of diverse food samples.

Flavonoids, total phenolics and antioxidant capacity: comparison between commercial green tea preparations

“…The stable DPPH • and the chemically generated ABTS •+ are still highly utilized in antioxidant research due to their simple reaction systems, which involve only the direct reaction between the radical and the antioxidants and have no other interference such as enzyme inhibition or the presence of multiple radicals, although they are not as physiologically relevant as the ORAC, which determines the peroxyl radical scavenging capacities. The DPPH • scavenging capacity assay is considered to be a valid and easy colorimetric method for antioxidant property evaluation, and the ORAC method has been indicated as the more physiologically significant (CHENG; MOORE; YU, 2006;DÁVALOS;GÓMEZ-CORDOVÉS;BARTOLOMÉ, 2004).…”

“…The assay was based on the procedure described by Dávalos, Gómez-Cordovés and Bartolomé (2004), adapted to individual cuvettes. The reaction was carried out in 75 mM phosphate buffer (pH 7.4), and the final reaction mixture was 2 mL.…”

2-Styrylchromones: Novel strong scavengers of reactive oxygen and nitrogen species

“…57 The net protection provided by a putative antioxidant sample was calculated using the difference between the area under the fluorescence decay curve in the presence of the sample (AUC sample ) and in its absence (AUC blank ). Regression equations between net AUC and the concentration of the sample were calculated for all the compounds.…”

Characterization and effect of clarified araçá (Psidium guineenses Sw.) juice on postprandial glycemia in healthy subjects

“…The determination was performed according to the method of Dávalos, Gómez-Cordovés and Bartolomé (2004). The results were expressed as µmol of Trolox equivalent (TE) per 300 mL of juice.…”