Dietary beta-D-glucan is associated with low blood cholesterol levels
due to increased excretion of bile acids, but there is little evidence
for the mechanism involved in enhanced bile acid clearance. Solid-sta
te C-13 NMR spectroscopy has now been used to investigate the possibil
ity of specific binding between a representative bile acid salt, glyco
cholic acid, and barley beta-glucan. From the similarity in chemical s
hift values for beta-D-glucan in the solid and solution states, it is
concluded that the beta-D-glucan adopts the same conformation in both
states. The dye Congo red is known to form a complex with beta-D-gluca
n that can precipitate from aqueous solution. In this case, the format
ion of a complex involving specific binding was evidenced by the appea
rance in the solid-state spectrum of resonances characteristic of the
dye molecule, that otherwise would not be present. In contrast, no res
onances characteristic of the bile acid were observed in the solid-sta
te NMR spectrum of the mixture of beta-D-glucan and the bile acid salt
. These results suggest that the hypocholesterolemic property of beta-
D-glucan does not involve a simple binding of bile acid salt molecules
to specific sites on the beta-D-glucan polymer. Copyright (C) 1996 El
sevier Science Ltd