Phenilpropanoate identification in young wheat plants by liquid chromatography/tandem mass spectrometry: monomeric and dimeric compounds

Metabolomic approach has become a very important tool for determining the actual gene expression and protein activity. Metabolism via the shikimate pathway in plant gives rise to a large number of aromatic compounds, including p-hydroxycinnamates, which are mainly associated with their cell walls in complex structures, ester-linked to heteroxilans. In this work, ferulate dehydrodimers and related compounds were extracted from the cell walls of young lyophilized wheat plants with 2 mol/l NaOH for 4 h at 25 °C under N(2). After solid phase extraction, samples were analysed by high-performance liquid chromatography-quadrupole-linear ion trap tandem mass spectrometry with the electrospray source operating in negative mode. Nineteen dehydrodiferulates, 2 hydrate forms, 3 oxo- forms, 2 decarboxilated forms and 1 dihydroxysinapate, were identified by mass spectra interpretation. In addition, five mixed dehydrodimers of ferulic-sinapic, ferulic-coumaric and ferulic-syringic acids were also identified. Reproducibility of peak areas was usually better than 10% but some minor components which may be procedural artefacts, although relatively mild conditions were used.