title: Prevention of a systematic underestimation of antioxidant activity in competition assays. The impact of unspecific reactions of the reactive species.
abstract: In antioxidant competition assays, an antioxidant (A) and a detector compound (D) compete for a reactive species (R). In the evaluation of these assays, it is tacitly assumed that all of R is captured by either D or A. Due to the - by definition - high reactivity of R, unspecific reactions of R are likely to occur and neglecting these reactions will result in a systematic underestimation of antioxidant activity. It was shown that in the standard hydroxyl radical scavenging assay this was indeed the case; the inaccurate mathematical evaluation resulted in an underestimation of antioxidant activity of 25% in this competition assay. The systematic underestimation of antioxidant activity can be prevented by using an adjusted Stern-Volmer equation that takes into account that only part of R is captured by D or A.
authors.affiliation: Department of Pharmacology and Toxicology, Maastricht University, 6200 MD Maastricht, The Netherlands.
authors.forename: Christiaan P
authors.initials: CP
authors.lastname: Beljaars
authors.forename: Jiska M
authors.initials: JM
authors.lastname: Balk
authors.forename: Aalt
authors.initials: A
authors.lastname: Bast
authors.forename: Guido R M M
authors.initials: GR
authors.lastname: Haenen
mesh_terms: D016166:Free Radical Scavengers / Q000737:chemistry*; D005609:Free Radicals / Q000737:chemistry*; D008432:Mathematical Computing
chemical_list: D016166:Free Radical Scavengers; D005609:Free Radicals