title: Antioxidant activity of phenolic acids in lipid oxidation catalyzed by different prooxidants.
abstract: The antioxidant activity of three naturally occurring phenolic acids, caffeic (CaA), ferulic (FeA), and p-coumaric acid (CoA), and a synthetic compound, propyl gallate (PG), was evaluated in a food-related model system, a liposome dispersion of marine polyunsaturated fatty acids. Oxidation was induced by two different prooxidants, free iron ions and bovine hemoglobin (Hb). Continuous measurement of oxygen uptake was used to quantify the rate of lipid oxidation at steady state. Free iron-induced oxidation was reduced in the following order: PG > FeA > CoA. Caffeic acid worked as a prooxidant and increased the oxidation rate by a factor of 9. For Hb-induced oxidation, the relative efficiency was PG > CaA approximately FeA >> CoA. The antioxidant activity was also evaluated by four antioxidant capacity assays. In the Folin-Ciocalteu, ferric reducing/antioxidant power, and 2,2-diphenyl-1-picrylhydrazyl radical scavenging assays, the antioxidant activity followed the sequence PG > CaA > FeA > CoA. The order for the 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) assay was found to be PG > CoA approximately FeA > CaA. The assays mainly reflected reducing abilities of the compounds. This work reports that in addition to the differences in the chemical structure of antioxidants, the antioxidant activity of phenolic compounds depends also upon the type of prooxidant.
authors.affiliation: Institute of Food Chemistry and Biotechnology, Faculty of Chemistry, Brno University of Technology, Purkynova 118, 612 00 Brno, Czech Republic.
authors.forename: Vera
authors.initials: V
authors.lastname: Kristinová
authors.forename: Revilija
authors.initials: R
authors.lastname: Mozuraityte
authors.forename: Ivar
authors.initials: I
authors.lastname: Storrø
authors.forename: Turid
authors.initials: T
authors.lastname: Rustad
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000737:chemistry*; D002384:Catalysis; D002417:Cattle; D005231:Fatty Acids, Unsaturated / Q000737:chemistry*; D006454:Hemoglobins / Q000737:chemistry; D062385:Hydroxybenzoates / Q000737:chemistry*; D007501:Iron / Q000737:chemistry; D010084:Oxidation-Reduction; D017382:Reactive Oxygen Species / Q000737:chemistry*
chemical_list: D000975:Antioxidants; D005231:Fatty Acids, Unsaturated; D006454:Hemoglobins; D062385:Hydroxybenzoates; D017382:Reactive Oxygen Species; D007501:Iron; C017616:phenolic acid