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Evaluation of Oxidative Stress in Biological Samples Using the Thiobarbituric Acid Reactive Substances Assay
Published on: May 12, 2020
An assay for pro-oxidant reactivity based on phenoxyl radicals generated by laccase
Augustin Cătălin Moţ1, Cristina Coman, Carmen Miron
1Department of Chemistry and Chemical Engineering, "Babes-Bolyai" University, 1 Mihail Kogălniceanu Str, Cluj-Napoca RO-400084, Romania.
Abstract:
A transient species may be detected with UV-vis and EPR spectroscopy during turnover of a laccase with quercetin; this species is assigned as a quercetin-derived radical, based on EPR spectra as well the observed UV-vis similarities (a 540nm centred band) with previously reported data. The rates of formation and decay of this species correlate well (r=0.9946) with the pro-oxidant reactivity manifested by flavonoids in the presence of laccase. An assay for the pro-oxidant reactivity of natural products is hence proposed based on the results reported here; its application is demonstrated for a series of pure compounds as well as for several propolis extracts. This assay has the advantages of using a biologically relevant process (haemoglobin oxidation), and not requiring the addition of oxidising agents such as peroxide or superoxide. Correlations, or the lack thereof, between the pro-oxidant parameters and the redox potentials, antioxidant capacities and lipophilicities, were analysed. The laccase employed in our study does display reactivity-related similarities to a range of other proteins, including human plasma ceruloplasmin.
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