Combined mass spectrometric and chromatographic methods for in-depth analysis of phenolic secondary metabolites in barley leaves

Abstract

Structural analysis via HPLC-ESI-MSn, UPLC-HESI-MS/MS and NMR reported 152 phenolic secondary metabolites in spring barley seedlings (Hordeum vulgare L.). Flavonoids with various patterns of glycosylation and acylation, as well as hydroxycinnamic acid glycosides, esters and amides, were identified in methanolic extracts from leaves of nine varieties of barley originating from different regions of the world. Hordatines derivatives, flavones acylated directly on the aglycone, and hydroxyferulic acid derivatives deserve special attention. Preparative chromatography enabled characterization of a number of compounds at trace levels with the 6-C-[6″-O-glycosyl]-glycosides and the 6-C-[2″,6″-di-O-glycosides]-glucoside structure of flavones. Derivatives of flavonols, quercetin and isorhamnetin were observed only in Syrian varieties. The ultra performance liquid chromatography profiles of UV-absorbing secondary metabolites were used for chemotaxonomic comparison between nine varieties of barley from different climatic conditions. The hierarchical clustering of bred lines from the Fertile Crescent and European and American varieties indicates a great diversity of chemical phenotypes within barley species.

Combined GC- and UHPLC-HR-MS Based Metabolomics to Analyze Durable Anti-fungal Resistance Processes in Cereals

“…To account for variances that arose from sample prepara- glucoside (C 23 H 38 O 20 ) in barley leaves. [19] Flavonoid concentrations are known to fluctuate in response to plant stress, [14] or the observed metabolites might undergo an unknown biotransformation. Genes of the phenylalanine pathway and flavonoid biosynthesis were induced in Lr34 barley, but the identified flavones were decreased.…”

Effect of pulsed light on postharvest disease control-related metabolomic variation in melon (Cucumis melo) artificially inoculated with Fusarium pallidoroseum

“…This compound was characterized as apigenin-6-Cglucosyl-2 00 -O-glucoside, also known as 4 00 -O-glucosylvitexin or isovitexin-2 00 -O-glucoside [44, 47]. Peak 5 (t R = 4.11 min) showed in the mass spectrum as the precursor ion m/z 623.1591 [M-H] − and its respective fragment ions m/z 443.1021 [M-H-162+18] -, which suggested the loss of a glucose moiety, one unit of water, and the fragment ion m/z 323.0592 [M-H-120] -.These patterns of fragmentation indicate the presence of a diglucoside linkage; thus, compound 5 was tentatively identified as isoscoparin 2 00 -O-glucoside[48].…”

Effect of pulsed light on postharvest disease control-related metabolomic variation in melon (Cucumis melo) artificially inoculated with Fusarium pallidoroseum

“…The peak 5 (t r = 4.11 min) showed in the mass spectrum a precursor ion m/z 623.1591 [M-H] - and its respective fragment ion m/z 443.1021 [M-H-162+18] - , which suggested loss of a glucose moiety and one unit of water and the fragment ion m/z 323.0592 [M-H-120] - . These patterns of fragmentation indicate the a presence of a diglucoside linkage and thus, compound 5 was tentatively identified as isoscoparin 2”- O -glucoside [31].…”

“…The peak 9 (t r = 4.49 min) represents compound 9 with a mass spectrum showing the ion m/z 799.2114 [M-H] - and its fragment m/z 461.1159 [M-H-338] - representing a loss of feruloyl plus a glucoside moiety and m/z 341.0681 [M-H-feruloyl-Glucoside-120] - .Thus, based on fragmentation, the metabolite was tentatively identified as isoscoparin 7- O -[6′′-feruloyl]-glucoside [31]…”