Arabinoxylan structures vary based on the degree and pattern of substitution of the b-(1?4)-linked D-xylopyranose backbone with a-Larabinofuranose units, acetyl groups, uronic acids, and feruloylated side chains. Substitution differences affect arabinoxylans' physicochemical and physiological characteristics. Wheat bran arabinoxylans were hydrolyzed with GH10 and GH11 endo-1,4-b-xylanases, and feruloylated oligosaccharides were isolated and purified (Amberlite XAD-2 isolation, Sephadex LH-20 gel permeation chromatography, and preparative reversed-phase HPLC). The pure, isolated compounds were structurally characterized via liquid chromatography-electrospray ionization-mass spectrometry and onedimensional and two-dimensional NMR analyses. In addition to the wellknown products of endo-xylanase hydrolysis (xylotriose and xylobiose O-3-substituted with a 5-O-trans-feruloyl-a-arabinofuranosyl unit on the middle and nonreducing xylose residue, respectively), novel structural features, including O-2-monosubstitution of xylose adjacent to a xylose carrying feruloylated arabinose, were observed. Additionally, a simultaneously acetylated and feruloylated oligosaccharide has been isolated and tentatively characterized. Oligosaccharides esterified with caffeic acid were also isolated, but these were proven to result, at least in part, as artifacts of the enzymatic hydrolysis.
|Number of pages||9|
|State||Published - Sep 1 2016|
Bibliographical noteFunding Information:
The authors thank Martin Waterstraat for providing the [13 C2 ]-labeled caffeic acid standard compound and for his assistance with LC-MS/MS measurements. The authors also thank Catrin Tyl for performing the NMR measurements of compounds 3, 5, and 6 at the Minnesota NMR Center in Minneapolis, MN, U.S.A. The Minnesota NMR Center receives funding for NMR instrumentation from the Office of the Vice President for Research, the Medical School, and the College of Biological Science at the University of Minnesota-Twin Cities, as well as NIH, NSF, and the Minnesota Medical Foundation.
© 2016 AACC International, Inc.
ASJC Scopus subject areas
- Food Science
- Organic Chemistry