Original scientific paper

https://doi.org/10.17113/ftb.54.02.16.4063

Involvement of α-, γ- and δ-Tocopherol Isomers from Pumpkin (Cucurbita pepo L.) Seed Oil or Oil Mixtures in the Biphasic DPPH˙ Disappearance Kinetics

Dalibor Broznić orcid.org/0000-0003-3935-5338 ; Faculty of Medicine, University of Rijeka, Rijeka, Croatia
Gordana Čanadi Jurešić orcid.org/0000-0003-0128-4634 ; Faculty of Medicine, University of Rijeka, Rijeka, Croatia
Čedomila Milin ; Faculty of Medicine, University of Rijeka, Rijeka, Croatia

Abstract

The antioxidant activity of three types of pumpkin seed oil or oil mixtures (cold-pressed, produced from roasted seed paste and salad) produced in the northern part of Croatia and the kinetics of their behaviour as free radical scavengers were investigated using DPPH˙. In addition, the involvement of oil tocopherol isomers (α-, γ- and δ-) in different steps of DPPH˙ disappearance and their impact on the rate of reaction were analysed. The kinetics of DPPH˙ disappearance is a two-step process. In the first step, rapid disappearance of DPPH˙ occurs during the first 11 min of the reaction, depending on the oil type, followed by a slower decline in the second step. To describe DPPH˙ disappearance kinetics, six mathematical models (mono- and biphasic) were tested. Our findings showed that γ- and δ-tocopherols affected DPPH˙ disappearance during the first step, and α-tocopherol in the second step of the reaction. Moreover, α-tocopherol demonstrated 30 times higher antioxidant activity than γ- and δ-tocopherols. The results indicated the biphasic double-exponential behaviour of DPPH˙ disappearance in oil samples, due to the complexity of reactions that involve different tocopherol isomers and proceed through different chemical pathways.

Keywords

DPPH˙ disappearance kinetics; mathematical modelling; pumpkin seed oil; tocopherols

Hrčak ID:

160362

URI

https://hrcak.srce.hr/160362

Publication date:

24.6.2016.

Article data in other languages: croatian

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