Fig. 8

Schematic presentation of tyrosine metabolism leading to the production of hydroxycinnamic acid amides (HCAAs). A Tyramine and the two catecholamines have been shown to have high antioxidant properties [34]. B Each compound shown in the pathway may be conjugated to hydroxycinnamic acid (HCA) derivatives (e.g., ferulic acid as shown). The most common conjugates include coumaric- and ferulic acid. Several sources have described the incorporation of the HCAAs into the cell wall [36, 37]. Compounds that were not detected as discriminant ions due to the flagellin elicitor treatments are lightly shaded i.e., tyrosine and L-DOPA. Dashed arrows indicate multiple enzymatic reactions leading to the production of a specific compound. Abbreviations: TH, tyrosine hydroxylase; TDC, tyrosine decarboxylase; DDC, dopa decarboxylase; MPH, monophenol hydroxylase; DH, dopamine hydroxylase; THT, tyramine N-(hydroxycinnamoyl) transferase