Publication detail

Antioxidant activity depends on the type of pro-oxidant

KRISTINOVÁ, V.

Original Title

Type

conference proceedings

Language

English

Original Abstract

Antioxidant activities of phenolic compounds have been of great interest for fatty food producers, however the activities substantially vary from one food application to another. In the present study we evaluated antioxidant activities of four phenolic compounds - propyl gallate, caffeic, ferulic, and p-coumaric acid. The activity of these antioxidants has been studied in relation to the type of pro-oxidant in a lipid system. To study oxidation, an emulsion-related food model system consisting of marine phospholipids in liposomes was used, in which the consumption of dissolved oxygen was continuously recorded to calculate the rate of lipid oxidation. Iron ions (Fe2+, Fe3+) and bovine hemoglobin (Hb), were applied to initiate lipid oxidation. In iron mediated oxidation, the expected antioxidant, caffeic acid, showed strong pro-oxidant activity, increasing the oxidation rate by almost 10 times. Among the other antioxidants propyl gallate was the most active compound, while ferulic and p-coumaric acids showed weaker antioxidant capacity. In Hb-mediated oxidation all the tested phenolics were efficient antioxidants, in a relative order (at 200 M): Propyl gallate > caffeic acid ~ ferulic acid >> p-coumaric acid. Cafeic acid demonstrated that the state of iron, free ions vs iron bound in the heme structure, is very important for the activity of phenolic antioxidants. This also shows that different reaction mechanisms are involved in interactions between free iron, hemoglobin and phenolic compounds. The antioxidant activity was also evaluated by four one-dimensional spectrophotometric methods: Folin-Ciocaltau (FC), Ferric Reducing/Antioxidant Power (FRAP), 2,2-Diphenyl-1-picrylhydrazyl Radical Scavenging (DPPH), and 2,2'-azinobis-3-ethylbenzotiazoline-6-sulfonic acid (ABTS) assay. The FC, FRAP and DPPH assays all showed that propyl gallate had the highest antioxidant activity followed by caffeic, ferulic and p-coumaric acid, the same relative order as found in Hb-mediated oxidation. Also in the ABTS assay, propyl gallate was found to have the highest activity followed by p-coumaric and ferulic acid while caffeic acid was found to have the lowest antioxidant activity. None of these spectrophotometric methods predicted that caffeic acid acts as a strong prooxidant in iron mediated oxidation of lipids.

Keywords

Phenolic antioxidants, caffeic acid, marine lipids, lipid oxidation, prooxidants, iron, hemoglobin, oxygen uptake

Authors

KRISTINOVÁ, V.

Released

6. 9. 2010

Location

Oslo, Norway

BibTex

@proceedings{BUT65878,
  editor="Věra {Kristinová}",
  title="Antioxidant activity depends on the type of pro-oxidant",
  year="2010",
  address="Oslo, Norway"
}