title: Analytical parameters of the microplate-based ORAC-pyrogallol red assay.
abstract: The analytical parameters of the microplate-based oxygen radicals absorbance capacity (ORAC) method using pyrogallol red (PGR) as probe (ORAC-PGR) are presented. In addition, the antioxidant capacity of commercial beverages, such as wines, fruit juices, and iced teas, is estimated. A good linearity of the area under the curve (AUC) versus Trolox concentration plots was obtained [AUC = (845 +/- 110) + (23 +/- 2) [Trolox, microM], R = 0.9961, n = 19]. QC experiments showed better precision and accuracy at the highest Trolox concentration (40 microM) with RSD and REC (recuperation) values of 1.7 and 101.0%, respectively. When red wine was used as sample, the method also showed good linearity [AUC = (787 +/- 77) + (690 +/- 60) [red wine, microL/mL]; R = 0.9926, n = 17], precision and accuracy with RSD values from 1.4 to 8.3%, and REC values that ranged from 89.7 to 103.8%. Additivity assays using solutions containing gallic acid and Trolox (or red wine) showed an additive protection of PGR given by the samples. Red wines showed higher ORAC-PGR values than white wines, while the ORAC-PGR index of fruit juices and iced teas presented a great variability, ranging from 0.6 to 21.6 mM of Trolox equivalents. This variability was also observed for juices of the same fruit, showing the influence of the brand on the ORAC-PGR index. The ORAC-PGR methodology can be applied in a microplate reader with good linearity, precision, and accuracy.
authors.affiliation: Pontificia Universidad Católica de Chile, Facultad de Química, Departamento de Farmacia, C.P. 782 0436, Santiago, Chile.
authors.forename: Rocío
authors.initials: R
authors.lastname: Ortiz
authors.forename: Mónica
authors.initials: M
authors.lastname: Antilén
authors.forename: Hernán
authors.initials: H
authors.lastname: Speisky
authors.forename: Margarita E
authors.initials: ME
authors.lastname: Aliaga
authors.forename: Camilo
authors.initials: C
authors.lastname: López-Alarcón
mesh_terms: D000975:Antioxidants / Q000737:chemistry*; D019540:Area Under Curve; D002839:Chromans / Q000737:chemistry; D005707:Gallic Acid / Q000737:chemistry; D007202:Indicators and Reagents; D011748:Pyrogallol / Q000031:analogs & derivatives* / Q000737:chemistry; D011786:Quality Control; D017382:Reactive Oxygen Species / Q000737:chemistry*; D012015:Reference Standards; D015203:Reproducibility of Results; D012996:Solutions; D014920:Wine / Q000032:analysis
chemical_list: D000975:Antioxidants; D002839:Chromans; D007202:Indicators and Reagents; D017382:Reactive Oxygen Species; D012996:Solutions; D011748:Pyrogallol; C058731:pyrogallol sulfonphthalein; D005707:Gallic Acid; C010643:6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid