title: o-Quinone involvement in the prooxidant tendency of a mixture of quercetin and caffeic acid.
abstract: The oxidation products of a previously tested prooxidant mixture of quercetin (Q) and caffeic acid (CA) at 1:2 ratio were analysed by LC-MS. The UV-Vis and MS spectra of three chromatographic peaks eluting at t(R)=9.11min, t(R)=14.36min and t(R)=30.30min were studied further. The structures of the tentatively identified compounds indicate polymeric molecules. A pentamer formed by 3 units of quercetin and 2 units of caffeic acid was attributed in the case of peaks t(R)=9.11min and t(R)=14.36min. The quercetin quinone (QQ) - a polymerization intermediate - is a fragment of the compound identified in the MS spectrum with the m/z=323 coming from Q o-quinone m/z=300 plus 23 from Na(+). According to the UV-Vis spectrum, we suggest a different intermolecular arrangement which gives a more extended e-delocalisation. At t(R)=30.30min, the spectra helped us to tentatively identify this oxidation product as being a polymer of 4 CA units and 1 QQ.
authors.affiliation: Laboratory of Animal Biology, National Research Development Institute for Animal Biology and Nutrition Baloteşti (IBNA), Calea Bucuresti nr. 1, Balotesti, Ilfov 077015, Romania; Department of Life Science and Biotechnology, Faculty of Life and Environmental Science, Shimane University, Matsue, Japan.
authors.forename: Veronica Sanda
authors.initials: VS
authors.lastname: Chedea
authors.forename: Lamis
authors.initials: L
authors.lastname: Choueiri
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Jisaka
authors.forename: Panagiotis
authors.initials: P
authors.lastname: Kefalas
mesh_terms: D002109:Caffeic Acids / Q000737:chemistry*; D016877:Oxidants / Q000737:chemistry*; D010084:Oxidation-Reduction; D011794:Quercetin / Q000737:chemistry*
chemical_list: D002109:Caffeic Acids; D016877:Oxidants; D011794:Quercetin; C040048:caffeic acid