title: Rapid peroxyl radical scavenging capacity (PSC) assay for assessing both hydrophilic and lipophilic antioxidants.
abstract: This paper reports a simple, rapid, and sensitive assay for assessing peroxyl radical scavenging capacity (PSC) of both hydrophilic and lipophilic antioxidant compounds and food extracts. The assay is based on the degree of inhibition of dichlorofluorescin oxidation by antioxidants that scavenge peroxyl radicals, generated from thermal degradation of 2,2'-azobis(amidinopropane). For hydrophilic antioxidant activity, the dose required to cause a 50% inhibition of the reaction (EC(50)) ranged from 2.41 +/- 0.02 (EGCG) to 21.26 +/- 0.38 microM (ferulic acid). EC(50) values for the hydrophilic antioxidant activity of food extracts ranged from 309.2 +/- 3.63 (apple) to 3345.1 +/- 151.5 micromol of vitamin C equiv/100 g for wheat bran. The EC(50) values for lipophilic antioxidant activity were 1.58 +/- 0.11 (Trolox), 4.35 +/- 0.43 (alpha-tocopherol), 18.94 +/- 0.38 (BHA), and 182.69 +/- 13.7 microM (BHT). Whole grain lipophilic antioxidant activity ranged from 3.49 +/- 0.57 (wheat) to 8.79 +/- 1.98 micromol of alpha-tocopherol equiv/100 g of rice. Hydrophilic antioxidant activity contributed >98% of the total antioxidant activity (hydrophilic plus lipophilic) of whole grains tested. The PSC assay was accurate (86-108% recovery), precise (0.12-11% CV), and reproducible (12% RSD) and produced results comparable to those of similar published assays. The PSC assay can be routinely used to analyze or screen both hydrophilic and lipophilic antioxidants or food extracts and will be a valuable alternative biomarker for future epidemiological studies of chronic diseases.
authors.affiliation: Department of Food Science, Cornell University, Ithaca, New York 14853-7201, USA.
authors.forename: Kafui Kwami
authors.initials: KK
authors.lastname: Adom
authors.forename: Rui Hai
authors.initials: RH
authors.lastname: Liu
mesh_terms: D000975:Antioxidants / Q000032:analysis* / Q000737:chemistry* / Q000494:pharmacology; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D005452:Fluoresceins / Q000737:chemistry; D005504:Food Analysis; D016166:Free Radical Scavengers / Q000032:analysis*; D010084:Oxidation-Reduction; D010545:Peroxides
chemical_list: D000975:Antioxidants; D005452:Fluoresceins; D016166:Free Radical Scavengers; D010545:Peroxides; C049375:perhydroxyl radical; C037631:2',7'-dichlorofluorescein