0483712 - MBÚ 2018 RIV CH eng J - Journal Article
Catapano, M.C. - Tvrdý, V. - Karlíčková, J. - Migkos, T. - Valentová, Kateřina - Křen, Vladimír - Mladěnka, P.
The Stoichiometry of Isoquercitrin Complex with Iron or Copper Is Highly Dependent on Experimental Conditions.
Nutrients. Roč. 9, č. 11 (2017), s. 1193. ISSN 2072-6643. E-ISSN 2072-6643
R&D Projects: GA MŠMT(CZ) LD15082
Institutional support: RVO:61388971
Keywords : chelator * copper * quercetin-3-O-beta-glucopyranoside
OECD category: Biochemistry and molecular biology
Impact factor: 4.196, year: 2017

Interaction of flavonoids with transition metals can be partially responsible for their impact on humans. Stoichiometry of the iron/copper complex with a flavonoid glycoside isoquercitrin, a frequent component of food supplements, was assessed using competitive and non-competitive methods in four (patho)physiologically-relevant pH values (4.5. 5.5, 6.8, and 7.5). Isoquercitrin chelated all tested ions (Fe2+, Fe3+, Cu2+, and Cu+) but its affinity for Cu+ ions proved to be very low. In general, the chelation potency dropped with pH lowering. Metal complexes of 1:1 stoichiometry were mostly formed, however, they were not stable and the stoichiometry changed depending on conditions. Isoquercitrin was able to reduce both Cu2+ and Fe3+ ions at low ratios, but its reducing potential was diminished at higher ratios (isoquercitrin to metal) due to the metal chelation. In conclusion, this study emphasizes the need of using multiple different methods for the assessment of chelation potential in moderately-active metal chelators, like flavonoids.
Permanent Link: http://hdl.handle.net/11104/0278914