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 o f 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 d imers were in decreasing amounts: ((Z)-beta-{4-[(E)-2-carboxyvinyl]-2-metho xphenoxy}-4-hydroxy-3-methoxy-cinnamic acid (8-O-4'-DiFA); trans-5-[(E)-2-c arvoxyvinyl]-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'-dime thoxy-3,3'-bicinnamic acid (5-5'-DiFA) and (E,E)-4,4'-dihydroxy-3,5'-dimeth oxy-beta,3'-bicinnamic acid (8-5'-DiFA). The ferulic acid dehydrodimers wer e also synthesised by a simple procedure from ethyl ferulate using peroxida se and hydrogen peroxide. (C) 2000 Academic Press.