The influence of gamma-irradiation on the formation of free radicals and antioxidant status of oregano (Origanum vulgare L.)
2007
Horvathova, J.,Vyskumny Ustav Potravinarsky, Bratislava (Slovak Republic) | Suhaj, M.,Vyskumny Ustav Potravinarsky, Bratislava (Slovak Republic) | Polovka, M.,Vyskumny Ustav Potravinarsky, Bratislava (Slovak Republic) | Brezova, V.,Slovenska Technicka Univ., Bratislava (Slovak Republic). Ustav Fyzikalnej Chemie a Chemickej Fyziky | Simko, P.,Vyskumny Ustav Potravinarsky, Bratislava (Slovak Republic)
The influence of various gamma-radiation dose absorptions on oregano samples was monitored by means of electron paramagnetic resonance (EPR) spectroscopy. Further, the antioxidant activity of oregano methanol/water extracts was characterised using 1,1-diphenyl-2-picrylhydrazyl free radical (DPPH), thiobarbituric acid reactive substances (TBARS), ferric reducing power (FRP), and total content of phenolic compounds (TPC) assays. EPR spectroscopy was used for the investigation of the influence of the absorbed dose on the character of the paramagnetic structures formed, as well as for their thermal stability and life-time characterisation. Paramagnetic structures of different origin (mostly of cellulose and carbohydrate), possessing diverse thermal stability and life-time, were identified in the gamma-irradiated samples. Immediately after irradiation, a statistically significant increase of the TBARS values and the total content of phenolic compounds in methanol/water oregano extract was observed. The alterations of the antioxidant properties of oregano extracts with the time after the radiation treatment were also monitored. A substantial time-dependent decrease of antioxidant activity was observed, probably as a result of storage, with both irradiated and non-irradiated oregano samples, as obvious from the ferric reducing power test and the content of total phenolic substances. The influence of irradiation and subsequent storage on the DPPH radical-scavenging ability was negligible.
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