epiglucan and potassium-hydroxide

Microwave superheated water extractions (MWE) were performed to evaluate the feasibility of this technology for quantitative recovery of the arabinoxylans (AX) or arabinoxylo-oligosaccharides (AXOS) from brewers' spent grain (BSG). The AX+AXOS yield increased with the increase of the temperature in the range from 140 to 210 °C during 2 min. The higher temperatures promoted depolymerisation, debranching, and deesterification of the polysaccharides, with formation of brown products. The conditions that promote a compromise between the yield and the structure obtained, minimizing the thermal degradation of the fractions extracted by MWE are the following: (1) 140 °C, to remove the residual starch mixed with β-glucans; (2) Suspension of the residue left in water and treated at 180 °C; (3) suspension of the residue in 0.1 M KOH and treated at 180 °C. Using this sequential procedure, it was possible to extract 62% of BSG AX+AXOS, presenting degrees of polymerization ranging between 7 and 24 xylose residues, and a degree of phenolic acids esterification between 5 and 21%. The structural variability obtained by MWE allows defining specific types of compounds for different applications and uses depending on the extraction conditions used.

Topics: beta-Glucans; Edible Grain; Hordeum; Hydroxides; Liquid-Liquid Extraction; Microwaves; Oligosaccharides; Potassium Compounds; Temperature; Water; Xylans; Xylose

In previous study, an unbranched (1→6)-β-D-glucan with Mw 2.6kDa was isolated from fruit bodies of Bulgaria inquinans (Fries). In present paper, three branched (1→6)-β-D-glucans were obtained from the water-extracted residues by a sequential KOH-extraction, namely BIK2, BIK10 and BIK30. Their molecular weights were determined to be 37.5kDa (BIK2), 288.9kDa (BIK10) and 175.5kDa (BIK30). Structural analysis indicated that their backbones were substituted by single glucosyls at C-3 positions, the branching ratios were 0.01 (BIK2), 0.17 (BIK10), 0.25 (BIK30). Immunological tests showed that all the four β-D-glucans could significantly increase the ConA or LPS-induced lymphocytes proliferation in vivo. Moreover, branched (1→6)-β-D-glucans have more significantly lymphocytes proliferation activities than unbranched (1→6)-β-D-glucan, and the effect of (1→6)-β-D-glucans on lymphocytes proliferation increases along with molecular weights. The present results well enrich the structure-activity relationships of (1→6)-β-D-glucan, and indicate (1→6)-β-D-glucans from B. inquinans (Fries) are potential immunostimulating agents.

Topics: Adjuvants, Immunologic; Animals; Ascomycota; beta-Glucans; Cell Proliferation; Chemical Fractionation; Drug Evaluation, Preclinical; Female; Fruiting Bodies, Fungal; Fungal Polysaccharides; Hydroxides; Lipopolysaccharides; Lymphocytes; Male; Mice; Mice, Inbred ICR; Molecular Weight; Oxidation-Reduction; Potassium Compounds; Solubility; Structure-Activity Relationship; Water

An enzymatic method to measure β-glucan content (GEM assay) is applicable in a variety of matrices. The method is composed of swelling the sample with KOH and initial digestion with a lyticase, which is followed by treatment with a mixture of exo-1,3-β-d-glucanase and β-glucosidase that converts the β-glucan to glucose. The glucose generated by the enzymatic hydrolysis is measured by another enzymatic method. The method is shown to be accurate and precise. The method is selective and applicable to both highly branched and unbranched β-1,3-glucans.

Topics: beta-Glucosidase; Glucan 1,3-beta-Glucosidase; Glucan Endo-1,3-beta-D-Glucosidase; Glucans; Glucose; Glucose Oxidase; Hydroxides; Indicators and Reagents; Multienzyme Complexes; Peptide Hydrolases; Peroxidases; Potassium Compounds