caa a22 4500 445321121 CHVBK 20180317142704.0 cr unu---uuuuu 170323e20110201xx s 000 0 eng 10.1007/s10534-010-9372-7 doi (NATIONALLICENCE)springer-10.1007/s10534-010-9372-7 Interaction of quercetin with copper ions: complexation, oxidation and reactivity towards radicals [Elektronische Daten] [Anna Pękal, Magdalena Biesaga, Krystyna Pyrzynska] Quercetin, one of the most common dietary flavonols, was investigated in the presence of Cu(II) ions in methanolic solution in order to obtain some explanation on the mechanism interaction and its action against free radical-mediated damage. The spectroscopic studies (UV-VIS, IR, ESI-MS) were used to assess the extent to which it undergo complex formation through chelation or modification through oxidation. The reaction of quercetin with Cu(II) resulted in the formation of 1:1 metal-ligand complex (λmax=436nm) through the carbonyl oxygen and 3-OH group in C ring. Then quercetin is oxidized to the benzoquinone type products. The addition of EDTA destroyed the complex but did not regenerate the whole original spectrum of quercetin. From the other hand, the presence of EDTA inhibits formation of copper-quercetin complex and quercetin oxidation. The antioxidant activity of the Q+Cu solutions was evaluated by using 2,2-diphenyl-1-picrylhydrazyl radical (DPPH∙) radical scavenging method and from an electrochemical point of view. The complex is much more effective as free radical scaveninger than the free flavonoid. Springer Science+Business Media, LLC., 2010 Flavonoid nationallicence Quercetin nationallicence Copper complexation nationallicence Antioxidant properties nationallicence Pękal Anna Department of Chemistry, University of Warsaw, Warsaw, Poland aut Biesaga Magdalena Department of Chemistry, University of Warsaw, Warsaw, Poland aut Pyrzynska Krystyna Department of Chemistry, University of Warsaw, Warsaw, Poland aut BioMetals Springer Netherlands 24/1(2011-02-01), 41-49 0966-0844 24:1<41 2011 24 10534 https://doi.org/10.1007/s10534-010-9372-7 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10534-010-9372-7 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Pękal Anna Department of Chemistry, University of Warsaw, Warsaw, Poland aut NATIONALLICENCE 700 1- Biesaga Magdalena Department of Chemistry, University of Warsaw, Warsaw, Poland aut NATIONALLICENCE 700 1- Pyrzynska Krystyna Department of Chemistry, University of Warsaw, Warsaw, Poland aut NATIONALLICENCE 773 0- BioMetals Springer Netherlands 24/1(2011-02-01), 41-49 0966-0844 24:1<41 2011 24 10534 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer