Contribution information

Title Assessment of prooxidant reactivity of plant polyphenolics via EPR spectroscopy
Status Not decided yet
Type Lecture
Session Risk management and process safety
Authors C., Zagrean-Tuza1, T., Chmiel2, A., Mot3
1 Babes-Bolyai University, Faculty of Chemistry and Chemical Engineering, CLUJ-NAPOCA, Romania
2 Gdansk University of Technology, Faculty of Chemistry, Gdansk, Poland
3 Babes-Bolyai University, Faculty of Chemistry and Chemical Engineering, CLUJ-NAPOCA, Romania
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Brief content Polyphenolics are phytoconstituents widely distributed in fruits, vegetables and their processed products—juices, nectars, dried fruits or vegetables, powder fruit-based products—and are well known for their major wholesome biological activities such as cardioprotective, antithrombotic, anticancer, antioxidant, anti-inflammatory and others. Important classes of phenolic compounds include hydroxybenzoic and hydroxycinnamic acids, lignans, stilbenes and the most valuable class—flavonoids—which is divided in subgroups such as anthocyanins, flavonols, flavanols and others. However, some of the well-known antioxidants—ascorbic acid, vitamin E, flavonoids—might act as prooxidants, either due to the presence of a heavy metal or simply owing to their radical-based intermediates. In this work, two newly improved and validated assays for prooxidant reactivity determination will be presented. Prooxidant reactivity is directly related to plant products safety and long-term stability. One of the analytical methods involves in-situ enzymatically-generated phenolic-based radicals and monitoring their capacity to oxidize ferrous hemoglobin to methemoglobin, by means of visible molecular absorption spectroscopy whereas the second includes hydroxyl generation ability monitored via Electron Paramagnetic Spectroscopy. These physiologically-relevant assays will be corroborated with EPR spectroscopy data of semiquinone anion radicals, generated in alkali medium. Tentative mechanism of the generation of these radicals—together with their practical implications—will be presented. The analytical methods were applied on both pure relevant compounds, alone or in mixtures, as well as on real food-based samples.
ID 199