Abstract
Maize by-product from the bioethanol industry (distiller’s dried grains with solubles, DDGS) is a source of ferulated arabinoxylan (AX), which is a health-promoting polysaccharide. In the present study, AX from DDGS was fermented by a representative colonic bacterial mixture (Bifidobacterium longum, Bifidobacterium adolescentis, and Bacteroides ovatus), and the effect of the fermented AX (AX-f) on the proliferation of the cell line Caco-2 was investigated. AX was efficiently metabolized by these bacteria, as evidenced by a decrease in the polysaccharide molecular weight from 209 kDa to < 50 kDa in AX-f, the release of ferulic acid (FA) from polysaccharide chains (1.14 µg/mg AX-f), and the short-chain fatty acids (SCFA) production (277 µmol/50 mg AX). AX-f inhibited the proliferation of Caco-2 cells by 80–40% using concentrations from 125–1000 µg/mL. This dose-dependent inverse effect was attributed to the increased viscosity of the media due to the polysaccharide concentration. The results suggest that the AX-f dose range and the SCFA and free FA production are key determinants of antiproliferative activity. Using the same polysaccharide concentrations, non-fermented AX only inhibited the Caco-2 cells proliferation by 8%. These findings highlight the potential of AX recovered from the maize bioethanol industry as an antiproliferative agent once fermented by colonic bacteria.
Highlights
The bioethanol industry has been augmenting worldwide, especially in the UnitedStates, with maize being the primary raw material used for this purpose in that country
Bifidobacterium longum, Bifidobacterium adolescentis, and Bacteroides 5 of 12 ovatus, were selected to perform the in vitro fermentation of AX, as they have been found to be capable of degrading this polysaccharide [3,12,19]
Ferulated AX recovered from the maize bioethanol industry can be efficiently fermented by the colonic bacterial mixture of Bifidobacterium longum, Bifidobacterium adolescentis, and Bacteroides ovatus, and the generated product (AX-f) inhibits the proliferation of Caco-2 cells up to 80%
Summary
The bioethanol industry has been augmenting worldwide, especially in the UnitedStates, with maize being the primary raw material used for this purpose in that country. Distiller’s dried grains with solubles (DDGS), constituted from the non-starch maize components such as maize bran, is generated in huge magnitude as a by-product during bioethanol production. DDGS is sold for a very low price and is mainly used in animal production as a nutrient supplement. The development of value-added products from DDGS has been of interest in recent years. One of the principal components of DDGS is a dietary fiber and more precisely a ferulated arabinoxylan (AX). AX is the main non-starch polysaccharide from cereal grains with a basic structure consisting of a linear β-(1-4)-linked D-xylopyranosyl backbone chain with some α-L-arabinofuranose units attached to the O-2 and O-3 positions of xylose units [1]. Some ferulic acid (FA) residues can be esterified to the arabinose side chains through O-5 [2] (Figure 1)
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