Abstract: High intake of dietary fiber is claimed to protect against development of colorectal cancer. Barley is a rich source of dietary fiber, and possible immunomodulatory effects of barley polysaccharides might explain a potential protective effect. Dietary fiber was isolated by extraction and enzyme treatment. A mixed-linked β-glucan (WSM-TPX, 96.5% β-glucan, Mw 886 kDa), an arabinoxylan (WUM-BS-LA, 96.4% arabinoxylan, Mw 156 kDa), a mixed-linked β-glucan rich fraction containing 10% arabinoxylan (WSM-TP) and an arabinoxylan rich fraction containing 30% mixed-linked β-glucan (WUM-BS) showed no significant effect on IL-8 secretion and proliferation of two intestinal epithelial cell lines, Caco-2 and HT-29, and had no significant effect on the NF-κB activity in the monocytic cell line U937-3κB-LUC. Further enriched arabinoxylan fractions (WUM-BS-LA) from different barley varieties (Tyra, NK96300, SB94897 and CDCGainer) were less active than the mixed-linked β-glucan rich fractions (WSM-TP and WSM-TPX) in the complement-fixing test. The mixed-linked β-glucan rich fraction from NK96300 and CDCGainer showed similar activities as the positive control while mixed‑linked β-glucan rich fractions from Tyra and SB94897 were less active. From these results it is concluded that the isolated high molecular weight mixed-linked β-glucans and arabinoxylans from barley show low immunological responses in selected in vitro test systems and thus possible anti-colon cancer effects of barley dietary fiber cannot be explained by our observations.
Keywords: arabinoxylan; mixed-linked β-glucan; barley; Caco-2; complement-fixing test; dietary fiber; HT-29; IL-8; U937; NF-kappaB
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Samuelsen, A.B.; Rieder, A.; Grimmer, S.; Michaelsen, T.E.; Knutsen, S.H. Immunomodulatory Activity of Dietary Fiber: Arabinoxylan and Mixed-Linked Beta-Glucan Isolated from Barley Show Modest Activities in Vitro. Int. J. Mol. Sci. 2011, 12, 570-587.
Samuelsen AB, Rieder A, Grimmer S, Michaelsen TE, Knutsen SH. Immunomodulatory Activity of Dietary Fiber: Arabinoxylan and Mixed-Linked Beta-Glucan Isolated from Barley Show Modest Activities in Vitro. International Journal of Molecular Sciences. 2011; 12(1):570-587.
Samuelsen, Anne Berit; Rieder, Anne; Grimmer, Stine; Michaelsen, Terje E.; Knutsen, Svein H. 2011. "Immunomodulatory Activity of Dietary Fiber: Arabinoxylan and Mixed-Linked Beta-Glucan Isolated from Barley Show Modest Activities in Vitro." Int. J. Mol. Sci. 12, no. 1: 570-587.