Arabinoxylan from Corn Fiber Obtained through Alkaline Extraction and Membrane Purification: Relating Bioactivities with the Phenolic Compounds

Abstract

Arabinoxylan has prebiotic properties, as it is able to resist digestion in the small intestine and undergoes fermentation in the large intestine. In this work, arabinoxylan was extracted from corn fiber using an alkaline solution and further purified with membrane processing. It was found that the extracts were mainly composed of xylose (50–52%), arabinose (37–39%), galactose (9%) and glucose (1–4%), with an A/X ratio of 0.72–0.77. All the extracts were composed of phenolic compounds, including ferulic acid derivatives such as dimers, trimers and tetramers. The purified extract had a lower concentration of ferulic and p-coumaric acid (0.004 and 0.02 mg/mgdry_weight, respectively) when compared to raw extract (19.30 and 2.74 mg/mgdry_weight, respectively). The same effect was observed for the antioxidant activity, with purified extracts having a lower value (0.17 ± 0.02 µmol TEAC/mg) when compared to the raw extract (2.20 ± 0.35 µmol TEAC/mg). The purified extract showed a greater antiproliferative effect against the HT29 cell line with EC50 = 0.12 ± 0.02 mg/mL when compared to the raw extract (EC50 = 5.60 ± 1.6 mg/mL). Both raw and purified extracts did not show any cytotoxicity to the Caco-2 cell line in the maximum concentration tested (10 mg/mL).

The Potential Valorization of Corn Stalks by Alkaline Sequential Fractionation to Obtain Papermaking Fibers, Hemicelluloses, and Lignin—A Comprehensive Mass Balance Approach

“…In comparison to our previously published results, the purity of the HC samples in the current investigation was enhanced [ 37 ] as a direct result of the modification of the separation procedure consisting of the introduction of the supernatant concentration phase. The raw HC samples also presented arabinan contents ranging from 9% to 11.5%, confirming the arabinoxylan-type HC structure evidenced by multiple authors [ 80 , 81 ]. Galactose residues present in hemicelluloses’ hydrolysate also pointed to the existing galactan-type branches (2–5%) on the xylan backbone of alkaline CS HC samples [ 82 ].…”