title: Application of directly coupled HPLC-NMR-MS to the identification and confirmation of quercetin glycosides and phloretin glycosides in apple peel.
abstract: Directly coupled HPLC-NMR-MS was used to identify and confirm the presence of quercetin O-glycosides and phloretin O-glycosides in an extract of apple peel. From the MS and MS/MS data, the molecular weights of the intact molecules as well as those of quercetin and phloretin and their sugar moieties were deduced. The NMR data provided information on the identity of the compounds as well as the alpha and beta conformations and the position of the glycosides on quercetin and phloretin. The following O-glycosides of quercetin could be identified: quercetin-3-alpha-L-rhamnosyl-(1-->6)-beta-D-glucoside (rutin), quercetin-3-beta-D-galactoside (hyperin), quercetin-3-beta-D-glucoside (isoquercitrin), quercetin-3-beta-D-xyloside (reynoutrin), quercetin-3-alpha-L-arabinofuranoside (avicularin), and quercetin-3-alpha-L-rhamnoside (quercitrin). Phloretin was present as phloretin-2'-beta-D-glucoside (phloridzin) and the 2'-beta-D-xylosyl-(1-->6)-beta-D-glucoside. Concentrations were between 0.2 and 5 mg/g of apple peel.
authors.affiliation: State Institute for Quality Control of Agricultural Products (RIKILT), Wageningen, The Netherlands. a.lommen@rikilt.wag-ur.nl
authors.forename: A
authors.initials: A
authors.lastname: Lommen
authors.forename: M
authors.initials: M
authors.lastname: Godejohann
authors.forename: D P
authors.initials: DP
authors.lastname: Venema
authors.forename: P C
authors.initials: PC
authors.lastname: Hollman
authors.forename: M
authors.initials: M
authors.lastname: Spraul
mesh_terms: D002851:Chromatography, High Pressure Liquid; D006027:Glycosides / Q000032:analysis; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D010693:Phloretin / Q000032:analysis*; D011794:Quercetin / Q000032:analysis*; D019685:Rosales / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet
chemical_list: D006027:Glycosides; D011794:Quercetin; D010693:Phloretin