title: Quantitative metabolite profiling of edible onion species by NMR and HPLC-MS.
abstract: Allium genus is a treasure trove of valuable bioactive compounds with potentially therapeutically important properties. This work utilises HPLC-MS and a constrained total-line-shape (CTLS) approach applied to (1)H NMR spectra to quantify metabolites present in onion species to reveal important inter-species differences. Extensive differences were detected between the sugar concentrations in onion species. Yellow onion contained the highest and red onion the lowest amounts of amino acids. The main flavonol-glucosides were quercetin 3,4'-diglucoside and quercetin 4'-glucoside. In general, the levels of flavonols were, higher in yellow onions than in red onions, and garlic and leek contained a lower amount of flavonols than the other Allium species. Our results highlight how (1)H NMR together with HPLC-MS can be useful in the quantification and the identification of the most abundant metabolites, representing an efficient means to pinpoint important functional food ingredients from Allium species.
authors.affiliation: School of Pharmacy, Biocenter Kuopio, University of Eastern Finland, Kuopio, Finland.
authors.forename: Tuula H
authors.initials: TH
authors.lastname: Soininen
authors.affiliation: School of Pharmacy, Biocenter Kuopio, University of Eastern Finland, Kuopio, Finland.
authors.forename: Niko
authors.initials: N
authors.lastname: Jukarainen
authors.affiliation: School of Pharmacy, University of Eastern Finland, Finland.
authors.forename: Seppo O K
authors.initials: SO
authors.lastname: Auriola
authors.affiliation: Department of Biology, Natural Product Research Laboratories, University of Eastern Finland, Joensuu, Finland.
authors.forename: Riitta
authors.initials: R
authors.lastname: Julkunen-Tiitto
authors.affiliation: Department of Biology, University of Eastern Finland, Kuopio, Finland.
authors.forename: Reijo
authors.initials: R
authors.lastname: Karjalainen
authors.affiliation: School of Pharmacy, Biocenter Kuopio, University of Eastern Finland, Kuopio, Finland. Electronic address: jouko.vepsalainen@uef.fi.
authors.forename: Jouko J
authors.initials: JJ
authors.lastname: Vepsäläinen
mesh_terms: D000596:Amino Acids / Q000737:chemistry / Q000378:metabolism; D050260:Carbohydrate Metabolism; D002241:Carbohydrates / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D044948:Flavonols / Q000737:chemistry / Q000378:metabolism; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D013058:Mass Spectrometry / Q000379:methods*; D055442:Metabolome; D019697:Onions / Q000737:chemistry* / Q000145:classification / Q000378:metabolism; D010936:Plant Extracts / Q000737:chemistry*
chemical_list: D000596:Amino Acids; D002241:Carbohydrates; D044948:Flavonols; D010936:Plant Extracts
keywords: (1)H NMR; Allium species; Amino acids; Carbohydrates; Flavonols; Food components; HPLC–MS