title: Immunomodulatory activity of dietary fiber: arabinoxylan and mixed-linked beta-glucan isolated from barley show modest activities in vitro.
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.
authors.affiliation: Department of Pharmaceutical Chemistry, Pharmacognosy, School of Pharmacy, University of Oslo, Oslo N-0316, Norway.
authors.forename: Anne Berit
authors.initials: AB
authors.lastname: Samuelsen
authors.forename: Anne
authors.initials: A
authors.lastname: Rieder
authors.forename: Stine
authors.initials: S
authors.lastname: Grimmer
authors.forename: Terje E
authors.initials: TE
authors.lastname: Michaelsen
authors.forename: Svein H
authors.initials: SH
authors.lastname: Knutsen
mesh_terms: D018938:Caco-2 Cells; D004043:Dietary Fiber / Q000494:pharmacology*; D019073:HT29 Cells; D001467:Hordeum / Q000737:chemistry*; D006801:Humans; D016328:NF-kappa B / Q000494:pharmacology; D014990:Xylans / Q000737:chemistry / Q000276:immunology*; D047071:beta-Glucans / Q000737:chemistry / Q000276:immunology*
chemical_list: D004043:Dietary Fiber; D016328:NF-kappa B; D014990:Xylans; D047071:beta-Glucans; C085118:arabinoxylan