An assay for pro-oxidant reactivity based on phenoxyl radicals generated by laccase

作者：Mot Augustin Catalin^*; Coman Cristina; Miron Carmen; Damian Grigore; Sarbu Costel; Silaghi Dumitrescu Radu

来源：Food Chemistry, 2014, 143: 214-222.

DOI：10.1016/j.foodchem.2013.07.128

• Quercetin
• Flavonoid
• Radical
• Laccase
• Met-haemoglobin
• EPR
• Pro-oxidant
• antioxidant

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 540 nm 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.

• 出版日期2014-1-15