Ferulic Acid Dehydrodimers in Rye(Secale cereale L.)

Abstract Four ferulic acid dehydrodimers were isolated from rye bran and purified by preparative HPLC after alkaline hydrolysis. The identity of the compounds were confirmed by UV, 1 H and 13 C-NMR and mass spectroscopy. The content of the four identified dimers corresponded to a total dimer concentration of 307 μg/g (dry matter) of the whole grain. The concentrations in the bran fraction were 10–20 times higher than in the starchy endosperm. The four dimers were in decreasing amounts: (( Z )- β -{4-[( E )-2-carboxyvinyl]-2-methoxyphenoxy}-4-hydroxy-3-methoxy-cinnamic acid (8-O-4′-DiFA); trans -5-[( E )-2-carboxyvinyl]-2-(4-hydroxy-3-methoxy-phenyl)-7-methoxy-2,3-dihydrobenzofuran-3-carboxylic acid (8-5′-DiFA benzofuran form), ( E,E )-4,4′-dihydroxy-5,5′-dimethoxy-3,3′-bicinnamic acid (5-5′-DiFA) and ( E,E )-4,4′-dihydroxy-3,5′-dimethoxy-β,3′-bicinnamic acid (8-5′-DiFA). The ferulic acid dehydrodimers were also synthesised by a simple procedure from ethyl ferulate using peroxidase and hydrogen peroxide.