In Vitro Bile-Acid Binding and Fermentation of High, Medium, and Low Molecular Weight β-Glucan

Abstract

The impact of beta-glucan molecular weight (MW) on in vitro bile-acid binding and in vitro fermentation with human fecal flora was evaluated. beta-Glucan extracted from oat line 'N979-5-4' was treated with lichenase (1,3-1,4-beta-D-glucanase) to yield high (6.87x10(5) g/mol), medium (3.71x10(5) g/mol), and low (1.56x10(5) g/mol) MW fractions. The low MW beta-glucan bound more bile acid than did the high MW beta-glucan (p<0.05). If the positive control, cholestyramine, was considered to bind bile acid at 100%, the relative bile-acid binding of the original oat flour and the extracted beta-glucan with high, medium, and low MW was 15, 27, 24, and 21%, respectively. Significant effects of high, medium, and low MW beta-glucans on total SCFA were observed compared to the blank without substrate (p<0.05). There were no differences in pH changes and total gas production among high, medium, and low MW beta-glucans, and lactulose. The low MW beta-glucan produced greater amounts of SCFA than the high MW after 24 h of fermentation. Among the major SCFA, more propionate was produced from all MW fractions of extracted beta-glucans than from lactulose. In vitro fermentation of extracted beta-glucan fractions with different MW lowered pH and produced SCFA, providing potential biological function.

Impact of the Molecular Weight, Viscosity, and Solubility of β-Glucan on in Vitro Oat Starch Digestibility

“…When compared with the SE-HPLC chromatogram of β-glucan reported in our previous study, 26 the SE-HPLC chromatogram of β-glucan in the extract suspension was similar. In our previous study, the β-glucan was extracted from oat flour to have ∼90% purity.…”

Differentiation of Adsorptive and Viscous Effects of Dietary Fibres on Bile Acid Release by Means of In Vitro Digestion and Dialysis

“…This is in accordance with the in vivo findings of Wolever et al [36] that demonstrated higher cholesterol-lowering effects of oat β-glucan dependent on its molecular weight, and thus its contribution to viscosity. In contrast, Kim et al [37] reported the highest values of bile acid binding for oat fractions containing low molecular weight β-glucan. The authors concluded that other components of the oat fraction might also have contributed to the bile acid binding.…”

In vitro fermentation of nuts results in the formation of butyrate and c9,t11 conjugated linoleic acid as chemopreventive metabolites

“…Therefore, the reduction in DCA and iso-DCA may contribute to the prevention of CRC. One mechanism by which nuts and Synergy1 ® might reduce secondary BA concentrations could be by direct binding of BA by dietary fiber [48,49]. In addition, the SCFA-mediated lowering of pH values in the FS might lead to reduced solubility of secondary BA as well as a reduction in 7α-dehydroxylase activity, which catalyzes the conversion of primary into secondary BA [50].…”