title: Epicatechin and epigallocatechin gallate inhibit formation of intermediary radicals during heating of lysine and glucose.
abstract: High concentrations of the tea catechins epicatechin (EC) or epigallocatechin gallate (EGCG) inhibited formation of highly reactive intermediary radicals appearing during the Maillard reactions (MR), that take place during heating glucose and lysine at 70°C in EtOH/HEPES buffer at pH 7.0 and pH 8.0. Radicals were trapped by ethanol, which subsequently were converted into spin adducts of the spin trap α-(4-pyridyl N-oxide)-N-tert-butylnitrone (POBN). EGCG was found to be more efficient than EC as inhibitor of intermediary radicals during the MR. Based on UV/Vis-spectroscopy, measurement of oxygen consumption and LC-MS detection of intermediates, it is suggested that the quinone form of autoxidised EC reacts with lysine through either a Michael type addition or a "Strecker like" reaction and thereby influences the formation of intermediary MR products as well as radicals.
authors.affiliation: Food Chemistry, Department of Food Science, University of Copenhagen, Rolighedsvej 30, 1958 Frederiksberg C, Denmark.
authors.forename: J
authors.initials: J
authors.lastname: Yin
authors.forename: R V
authors.initials: RV
authors.lastname: Hedegaard
authors.forename: L H
authors.initials: LH
authors.lastname: Skibsted
authors.forename: M L
authors.initials: ML
authors.lastname: Andersen
mesh_terms: D028241:Camellia sinensis / Q000737:chemistry; D002392:Catechin / Q000031:analogs & derivatives / Q000737:chemistry*; D005609:Free Radicals / Q000737:chemistry*; D005947:Glucose / Q000737:chemistry*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D008239:Lysine / Q000737:chemistry*; D015416:Maillard Reaction; D010936:Plant Extracts / Q000737:chemistry*
chemical_list: D005609:Free Radicals; D010936:Plant Extracts; D002392:Catechin; C045651:epigallocatechin gallate; D005947:Glucose; D008239:Lysine
keywords: EC; EGCG; ESR; LC–MS; Maillard reactions; Oxygen consumption