Antioxidant and iron-chelating properties of taxifolin and its condensation product with glyoxylic acid
The condensation of taxifolin with glyoxylic acid was examined, and the properties of the resulting product were compared with those of taxifolin. The structure of the product was determined by NMR spectroscopy. The ability of the polyphenols to scavenge reactive oxygen species (ROS) was estimated by luminol-dependent chemiluminescence. The iron-chelating and iron-reducing activities were studied using absorption spectrophotometry. It was shown that the condensation leads to the formation of a dimer consisting of two taxifolin units linked through a carboxymethine bridge at the C-6 and C-8 positions of the A ring. The dimer exhibited a somewhat higher ROS scavenging activity than taxifolin. The iron-binding capacity of the compounds was proportional to the number of polyphenol units. The iron-reducing ability of the dimer was lower than that of taxifolin. Thus, the dimer possessed a higher antioxidant activity than the parent flavonoid. The data obtained may be useful for a better understanding of processes occurring in foods and beverages and in a search for new active compounds.
KeywordsTaxifolin Glyoxylic acid Condensation ROS scavenging activity Iron-chelating and iron-reducing activities
The Authors are thankful to Molchanov M.V. from the Institute of Theoretical and Experimental Biophysics for recording the NMR spectra. The study was carried out using the facilities of the Center of Collective Use of the Institute of Theoretical and Experimental Biophysics of Russian Academy of Sciences. This study was supported by the Russian Foundation for Basic Research [Projects Nos. 15-04-02377 (V.S.S) and 14-44-03622 (Y.V.S)].
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