Effect of periodate oxidation and borohydride reduction on the chemical structure and chain conformation of arabinoxylan

Journal article, 2026

The effect of periodate oxidation and borohydride reduction on arabinoxylan (AX) in aqueous solution was investigated using ¹³C NMR spectroscopy and small-angle X-ray scattering (SAXS). AX consists of a xylose backbone, which is mono- or di-substituted with arabinose. We show that at a ring-opening modification degree of 21%, periodate oxidation occurs predominantly on arabinose, and shows a preference for arabinose linked to di-substituted xylose units over the mono-substituted. With a higher degree of modification of 33%, arabinose at the mono-substituted position and unsubstituted xylose units are also modified. At 33% a large portion of oxidizable AX residues have been ring-opened, yet SAXS reveals no significant changes in chain conformation and only a minor reduction (10%) in persistence length for the oxidized-reduced dialcohol AX. With increasing degree of oxidation, dialdehyde AX instead show an increasing tendency for aggregation, attributed to chain cross-linking. Upon reduction of the dialdehyde and cross-linked groups to dialcohol AX, the chains revert back to having repulsive interactions, acting as chains in a good solvent environment.