It has been shown that a common side-chain of grass cell wall arabinoxylans is 2-O-beta-D-xylopyranosyl-(5-0-feruloyl)-L-arabinose [X(F)A]. The stability of X(F)A was determined by incubation of (feruloyl-U-C-14)-labelled X(F)A and (penrosyl-1-H-3)-labelled X(F)A anaerobically with rat caecal contents and chromatographic analysis of the radioactive products. The ester linkage was hydrolysed very rapidly to form ferulic acid (which was stable) and the disaccharide (XA). The H-3-XA was further metabolised, but H-3-monosaccharides did not accumulate. In the end-products of fermentation of (pentosyl-H-3)-labelled X(F)A, 67% of the H-3 was present in bacterial polymers. In contrast, when free [1-H-3] arabinose was incubated with rat caecal contents, 74% of the H-3 quickly became volatile, probably as (H2O)-H-3. It is concluded that X(F)A is highly susceptible to (feruloyl)esterase activity produced by bacteria present in the rat caecum, and that the disaccharide produced is further fermented, but not via the production of extracellular arabinose and xylose.
|Number of pages||5|
|Journal||Journal of the Science of Food and Agriculture|
|Publication status||Published - Mar 1997|