Ferulic acid dehydrodimers in rye (Secale cereale L.)

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, H-1 and C-13-NMR and mass spectroscopy. The content of the Four identified dimers corresponded to a total dimer concentration of 307 mu g/g (dry matter) of the whole grain. The concentrations in the bran fraction were 10-20 times higher than in the starchy endosperm. Thr Four dimers were in decreasing amounts: ((Z)-beta-{4-[(E)-2-carboxyvinyl]-2-methoxphenoxy}-4-hydroxy-3-methoxy-cinnamic acid (8-O-4'-DiFA); trans-5-[(E)-2-carvoxyvinyl]-2-(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-beta,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. (C) 2000 Academic Press.