Extending applicability of the oxygen radical absorbance capacity (ORAC-fluorescein) assay.
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.
Dávalos
Alberto
A
Instituto de Fermentaciones Industriales (CSIC), Juan de la Cierva 3, 28006 Madrid, Spain.
Gómez-Cordovés
Carmen
C
Bartolomé
Begoña
B
D000975:Antioxidants / Q000032:analysis*; D002839:Chromans; D019587:Dietary Supplements / Q000032:analysis; D019793:Fluorescein; D029963:Quercus; D017382:Reactive Oxygen Species / Q000737:chemistry*; D012680:Sensitivity and Specificity; D014920:Wine / Q000032:analysis; D014934:Wood
D000975:Antioxidants; D002839:Chromans; D017382:Reactive Oxygen Species; C010643:6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid; D019793:Fluorescein