title: Antioxidant-guided isolation and mass spectrometric identification of the major polyphenols in barley (Hordeum vulgare) grain.
abstract: In the present study, the relative contribution of individual/classes of polyphenols in barley, to its antioxidant properties, was evaluated. Flash chromatography was used to fractionate the total polyphenol extract of Irish barley cultivar 'Irina', and fractions with highest antioxidant properties were identified using total phenolic content and three in vitro antioxidant assays: DPPH, FRAP, and ORAC. Flavanols (catechin, procyanidin B, prodelphinidin B, procyanidin C) and a novel substituted flavanol (catechin dihexoside, C27H33O16(-), m/z 613.17), were identified as constituents of the fraction with highest antioxidant capacity. Upon identification of phenolics in the other active fractions, the order of most potent contributors to observed antioxidant capacity of barley extract were, flavanols>flavonols (quercetin)>hydroxycinnamic acids (ferulic, caffeic, coumaric acids). The most abundant polyphenol in the overall extract was ferulic acid (277.7μg/gdw barley), followed by procyanidin B (73.7μg/gdw barley).
authors.affiliation: Teagasc Food Research Centre, Ashtown, Dublin 15, Ireland; School of Agriculture and Food Science, University College Dublin, Dublin 4, Ireland. Electronic address: nirupama.gangopadhyay@teagasc.ie.
authors.forename: Nirupama
authors.initials: N
authors.lastname: Gangopadhyay
authors.affiliation: Teagasc Food Research Centre, Ashtown, Dublin 15, Ireland.
authors.forename: Dilip K
authors.initials: DK
authors.lastname: Rai
authors.affiliation: School of Agriculture and Food Science, University College Dublin, Dublin 4, Ireland.
authors.forename: Nigel P
authors.initials: NP
authors.lastname: Brunton
authors.affiliation: Teagasc Food Research Centre, Ashtown, Dublin 15, Ireland.
authors.forename: Eimear
authors.initials: E
authors.lastname: Gallagher
authors.affiliation: Teagasc Food Research Centre, Ashtown, Dublin 15, Ireland.
authors.forename: Mohammad B
authors.initials: MB
authors.lastname: Hossain
mesh_terms: D000975:Antioxidants / Q000737:chemistry*; D002523:Edible Grain / Q000737:chemistry; D001467:Hordeum / Q000737:chemistry*; D013058:Mass Spectrometry; D010936:Plant Extracts / Q000737:chemistry* / Q000302:isolation & purification; D059808:Polyphenols / Q000737:chemistry* / Q000302:isolation & purification; D012639:Seeds / Q000737:chemistry*
chemical_list: D000975:Antioxidants; D010936:Plant Extracts; D059808:Polyphenols
keywords: Antioxidant capacity; Barley; Flash chromatography; Flavanols; Mass spectrometry; Polyphenols