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.