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The Interactions Between Rapeseed Lipoxygenase and Native Polyphenolic Compounds in a Model System

Author:
Dwiecki, Krzysztof, Siger, Aleksander, Czubiński, Jarosław, Nogala-Kałucka, Małgorzata, Lampart-Szczapa, Eleonora
Source:
journal of the American Oil Chemists' Society 2012 v.89 no.3 pp. 379-387
ISSN:
0003-021X
Subject:
enzyme activation, polyphenols, linoleic acid, free radicals, linoleate 13S-lipoxygenase, phenolic acids, Brassica napus, antioxidant activity, rapeseed
Abstract:
The focus of the present research was to study inhibition of lipoxygenase activity by rapeseed native polyphenols and the interactions between those compounds and the enzyme. The enzyme and polyphenolic compounds (polyphenols, phenolic acids) were extracted from rapeseed (Brassica napus) varieties Aviso and PR45DO3. The total phenolic compounds concentration in tested rapeseed was 1,485–1,691 mg/100 g d.m. (dry matter) and the free phenolic acids content in both rapeseed varieties was about 76 μg/100 g d.m. The isolated proteins showed lipoxygenase activity. Prooxidant properties of phenolic compounds in the presence of lipoxygenase and linoleic acid were observed rather in the case of extracts containing a relatively high concentration of miscellaneous polyphenols. Antioxidant properties were recorded in the case of phenolic acid extracts which contain only 1.4–1.9% of phenolics present in raw phenolic extracts. We propose that the prooxidant effect of phenolic compounds comes from quinone and oxidized polyphenols formation. The observed antioxidant activity of phenolic acid extracts is probably due to their ability to scavenge free radicals formed from linoleic acid. However, reduction of lipoxygenase ferric to ferrous ions, which prevent the activation of the enzyme and inhibited its activity, was also observed.
Agid:
529172