Synthesis and antioxidant properties of caffeic acid corn bran arabinoxylan esters

As a potential of bioactive additives, corn bran arabinoxylan (CAX) was prominent in its probiotic benefits and immuno-enhancing activities. To improve the antioxidant ability of CAX, naturally occurring caffeic acid (CA) was covalently attached to CAX by esterification to generate caffeic acid corn bran arabinoxylan esters (CA-CAX) with various degrees of substitution (DS).

The structure of CA-CAX was analysed by NMR, and the DS was determined by HPLC. The antioxidant activity of CA-CAX was investigated on scavenging the 2,2'-diphenyl-1-picrylhydrazyl (DPPH) radical and autoxidazing methyl linoleate, and an aqueous linolenic acid dispersion was also used as an in vitro test system to examine the inhibition effect of CA-CAX on the lipid peroxidation level after UV exposure. The ability of CA-CAX to prevent H₂ O₂ -induced oxidative damage of cell was studied by reducing MDA levels and increasing SOD and GSH-Px activities in human hepatocarcinoma (HepG2) cell.

The results certificated that CA was linked to CAX successfully with various DS. Compared with CAX, the antioxidant capacity of CA-CAX was improved significantly and enhanced with the increasing concentration and DS.