Year: 2014
Type: dissertation
Abstract: The flavonols are one subgroup of the flavonoids which are aromatic secondary metabolites of plants.They occur in almost all parts of the plant being stored in cell vacuoles.The natural flavonoids are mainly in a glycosylated form since these are less reactive and more water-soluble than the flavonoid aglycones.These polyphenolic compounds exert a wide range of biological effects e.g.antimicrobial, anti-allergic and antioxidant effects.Onions belong to the genus Allium and the common table onion (Allium cepa) is cultivated almost everywhere in the world.Well-known and widely cultivated species of Allium include leek (Allium porrum L.), shallot (Allium ascalonicum Hort.), yellow and red onion (Allium cepa L.) and garlic (Allium sativum).In addition to their use in food preparation (Lanzotti 2006), onions are also utilized for their therapeutic properties.The aim of this study was to conduct an extensive profiling of the onion metabolites such as carbohydrates, free amino acid, organic acids and flavonoids.The flavonoids present of Allium porrum are poorly characterized within the onion genus and no comparisons have been conducted with this leek cultivar.First NMR, HPLC-MS methods were developed to analyze plant metabolites.These methods allowed quantification of several metabolites including flavonols from onion (Allium cepa).A comparison was made of the metabolites and flavonols of different onion species and cultivars: Allium cepa, Allium sativum, Allium ascalonicum Hort.and Allium porrum.The highest amounts of fructose and fructo-oligosaccharides were found in garlic and lowest in long shallot.The flavonol concentrations in leek were lower than those in the other species.The most abundant flavonols in leek were kaempferol derivatives.The white stalk and the light green stalk contained lower concentrations and a smaller number of different flavonoids than those in the green stalk.In leek cultivars ten-fold differences were found between some of the metabolites.
Author: Tuula H. Soininen
Language: English
Topic: Garlic and Onion Studies
Subfield: Plant Science
Domain: Life Sciences
SDG: Zero hunger
Open Access status: green
OpenAlex ID: W3097735047