title: Annotation of Different Dehydrocatechin Oligomers by MS/MS and Their Occurrence in Black Tea.
abstract: Dehydrocatechins (DhC's), oligomeric oxidation products of (epi)catechins, were formed in model incubations of epicatechin with mushroom tyrosinase. DhC oligomers up to tetramers were detected by reversed-phase ultrahigh-performance liquid chromatography mass spectrometry (RP-UHPLC-MS) analysis. Measurements with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) showed formation of oligomers up to at least 15 catechin subunits. Isomeric DhC's were obtained, and a method based on MS(2) fragment ratios was set up to distinguish between the different interflavanic configurations of the isomers. In the model incubation, 8 dehydrodicatechins (DhC2's) and 22 dehydrotricatechins (DhC3's) were tentatively annotated by their MS(2) signature fragments. Three different interflavanic configuration types were determined for the DhC2's. DhC2's and DhC3's were shown to occur in a black tea extract for the first time. For the DhC2's, at least two isomeric types, i.e., DhC β and DhC ε, could be annotated in black tea.
authors.affiliation: Laboratory of Food Chemistry, Wageningen University , P.O. Box 17, 6700 AA Wageningen, The Netherlands.
authors.forename: Annewieke J W
authors.initials: AJ
authors.lastname: Verloop
authors.affiliation: Laboratory of Food Chemistry, Wageningen University , P.O. Box 17, 6700 AA Wageningen, The Netherlands.
authors.forename: Harry
authors.initials: H
authors.lastname: Gruppen
authors.affiliation: Laboratory of Food Chemistry, Wageningen University , P.O. Box 17, 6700 AA Wageningen, The Netherlands.
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Vincken
mesh_terms: D002392:Catechin / Q000031:analogs & derivatives / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D015394:Molecular Structure; D044945:Proanthocyanidins / Q000737:chemistry; D052616:Solid Phase Extraction; D021241:Spectrometry, Mass, Electrospray Ionization; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D053719:Tandem Mass Spectrometry; D013662:Tea / Q000737:chemistry*; D014443:Tyrosine / Q000737:chemistry
chemical_list: D044945:Proanthocyanidins; D013662:Tea; C000615579:dehydrocatechin; D014443:Tyrosine; D002392:Catechin
keywords: MALDI-TOF-MS; UHPLC-MS/MS; black tea; catechins; dehydrocatechins; procyanidins; tyrosinase