title: Preliminary UHPLC-PDA-ESI-MS screening of light-accelerated autoxidation products of the tetrapyrrole biliverdin.
abstract: The application of phycobiliproteins, e.g. blue C-phycocyanin, as natural water-soluble food colourants is emerging. The chromophore of these proteins comprises a number of tetrapyrroles (or phycocyanobilins), which have an extensive conjugated system, vulnerable to autoxidation. To assess the autoxidation products, a simplified model system was used in which the free tetrapyrrole biliverdin, instead of phycobiliprotein, was subjected to light-accelerated autoxidation. Degradation products of biliverdin were subsequently annotated by reversed-phase ultra-high performance liquid chromatography with a photo diode array and positive mode in-line electrospray ionization mass spectrometry. To facilitate the analysis of degradation products, autoxidation of the three methine bridges in biliverdin was mimicked in silico. It was found that both the peripheral and central methine bridges of biliverdin were susceptible to light-accelerated autoxidation. Scission products tentatively annotated with MS(2) and MS(3) were propionic acid-containing pyrroles. From this, it can be speculated that tetrapyrroles attached to phycobiliproteins are susceptible to autoxidative degradation.
authors.affiliation: Wageningen University, Laboratory of Food Chemistry, P.O. Box 17, 6700 AA Wageningen, The Netherlands; FeyeCon Carbon Dioxide Technologies, Rijnkade 17a, 1382 GA Weesp, The Netherlands.
authors.forename: Yannick
authors.initials: Y
authors.lastname: Weesepoel
authors.affiliation: Wageningen University, Laboratory of Food Chemistry, P.O. Box 17, 6700 AA Wageningen, The Netherlands.
authors.forename: Harry
authors.initials: H
authors.lastname: Gruppen
authors.affiliation: Wageningen University, Laboratory of Food Chemistry, P.O. Box 17, 6700 AA Wageningen, The Netherlands. Electronic address: jean-paul.vincken@wur.nl.
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Vincken
mesh_terms: D001664:Biliverdine / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D008027:Light; D010084:Oxidation-Reduction; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
chemical_list: D001664:Biliverdine
keywords: Autoxidation; Biliverdin; LC–MS; Phycobiliprotein