Identification of hordatines and other phenolamides in barley (Hordeum vulgare) and beer by UPLC-QTOF-MS

• Novel hordatines in barley and beer were identified by UPLC-QTOF.
• Novel hordatine precursors in barley and beer were identified.
• Beer contains hordatines with high degree of glycosylation.
• Barley and beer contains a wide variety of hydroxycinnamoylspermidines.

Antifungal hordatines and their precursors, hydroxycinnamoylagmatines, were analyzed in dormant barley seeds and beer sample by ultra-performance liquid chromatography (UPLC) coupled to quadrupole time-of-flight mass spectrometry (QTOF-MS) operating in MSE-mode. Three hordatine basic structures, namely A, B and C, were found in barley and beer samples. All of these hordatines had analogous structures containing either one (hordatines A1, B1 and C1) or two (hordatines A2, B2 and C2) hydroxylated agmatine residues. All hordatines and hydroxycinnamoylagmatines were also present as sugar conjugates. Furthermore, N6 –methylated form of hordatines A, B and C, as well as their precursors, coumaroyl-N6-methylagmatine and feruloyl-N6-methylagmatine, were tentatively identified from barley samples. In addition, a number of other phenolamides, namely hydroxycinnamic acids conjugated to spermidine, were identified from barley and beer.