Cell wall polysaccharides of Chinese Wolfberry (Lycium barbarum): Part 2. Characterisation of arabinogalactan-proteins

Arabinogalactan-proteins (AGPs) were isolated from Wolfberry fruit (Lycium barbarum) and purified by anion-exchange chromatography and precipitation with Yariv reagent. Linkage and NMR analysis established the structure of Wolfberry AGP as typical of AGP reported from other sources. The data were consistent with a backbone of (1 -> 3)-linked beta-D-galactopyranosyl residues, many of which were substituted at O-6 with side chains of mainly 5-substituted alpha-L-arabinofuranosyl residues, terminated with alpha-(and beta-)L-arabinofuranosyl, alpha-L-rhamnopyranosyl and beta-D-glucopyranosyluronic acid residues. An unusual structural feature of the AGP was the occurrence of 4-substituted beta-D-glucopyranosyluronic acid residues in the side chains. The AGP, which had a MW average of between 50 and 60 kDa, displayed heterogeneity with regard to both galactose/arabinose ratio and degree of branching. Protein accounted for similar to 6% of the AGP and was rich in hydroxyproline. Evidence for an interaction between some of the AGP and hydrophobic moieties is presented. (C) 2011 Elsevier Ltd. All rights reserved

Cell wall polysaccharides of Chinese Wolfberry (Lycium barbarum): Part 2. Characterisation of arabinogalactan-proteins

Arabinogalactan-proteins (AGPs) were isolated from Wolfberry fruit (Lycium barbarum) and purified by anion-exchange chromatography and precipitation with Yariv reagent. Linkage and NMR analysis established the structure of Wolfberry AGP as typical of AGP reported from other sources. The data were consistent with a backbone of (1 -> 3)-linked beta-D-galactopyranosyl residues, many of which were substituted at O-6 with side chains of mainly 5-substituted alpha-L-arabinofuranosyl residues, terminated with alpha-(and beta-)L-arabinofuranosyl, alpha-L-rhamnopyranosyl and beta-D-glucopyranosyluronic acid residues. An unusual structural feature of the AGP was the occurrence of 4-substituted beta-D-glucopyranosyluronic acid residues in the side chains. The AGP, which had a MW average of between 50 and 60 kDa, displayed heterogeneity with regard to both galactose/arabinose ratio and degree of branching. Protein accounted for similar to 6% of the AGP and was rich in hydroxyproline. Evidence for an interaction between some of the AGP and hydrophobic moieties is presented. (C) 2011 Elsevier Ltd. All rights reserved

Cell wall polysaccharides of Chinese Wolfberry (Lycium barbarum):Part 1. Characterisation of soluble and insoluble polymer fractions

Water-soluble polysaccharides (WSP) and insoluble cell wall material (CWM) were isolated from Wolfberry fruit (Lycium barbarum). WSP were fractionated by treatment with a quaternary ammonium salt and anion-exchange chromatography. Pectic polysaccharides were major components but a glucan, xylan and arabinogalactan-proteins (AGP) were also present. CWM was fractionated into pectic and hemicellulosic polysaccharides by a sequential solvent extraction. The former were rhamnogalacturonans with varying degrees of branching of the backbone. A (4-O-methyl-glucurono)xylan was the predominant hemicellulose. The additional presence of xyloglucan and a mannan-based polymer, strongly attached to the cellulose fibrils was indicated. Of the 6.8% total polysaccharide content of Wolfberry fruit, 1.2% was readily water soluble, 5.6% insoluble and 0.3% was readily soluble AGP. (C) 2011 Elsevier Ltd. All rights reserved.</p

Oligomalt, a New Slowly Digestible Carbohydrate, Is Well Tolerated in Healthy Young Men and Women at Intakes Up to 180 Gram per Day: A Randomized, Double-Blind, Crossover Trial

In this randomized, double-blind triple-crossover study (NCT05142137), the digestive tolerance and safety of a novel, slowly digestible carbohydrate (SDC), oligomalt, an α-1,3/α-1,6-glucan α-glucose-based polymer, was assessed in healthy adults over three separate 7-day periods, comparing a high dose of oligomalt (180 g/day) or a moderate dose of oligomalt (80 g/day in combination with 100 g maltodextrin/day) with maltodextrin (180 g/day), provided as four daily servings in 300 mL of water with a meal. Each period was followed by a one-week washout. A total of 24 subjects (15 females, age 34 years, BMI 22.2 kg/m2, fasting blood glucose 4.9 mmol/L) were recruited, of whom 22 completed the course. The effects on the primary endpoint (the Gastrointestinal Symptom Rating Score (GSRS)) showed a statistically significant dose dependency, albeit of limited clinical relevance, between a high dose of oligomalt and maltodextrin (mean (95% CI) 2.29 [2.04, 2.54] vs. 1.59 [1.34, 1.83], respectively; difference: [−1.01, −0.4], p < 0.0001), driven by the GSRS-subdomains “Indigestion” and “Abdominal pain”. The GSRS difference ameliorated with product exposure, and the GSRS in those who received high-dose oligomalt as their third intervention period was similar to pre-intervention (mean ± standard deviation: 1.6 ± 0.4 and 1.4 ± 0.3, respectively). Oligomalt did not have a clinically meaningful impact on the Bristol Stool Scale, and it did not cause serious adverse events. These results support the use of oligomalt across various doses as an SDC in healthy, normal weight, young adults

Room-temperature-persistent magnetic interaction between coordination complexes and nanoparticles in maghemite-based nanohybrids

International audienceMaghemite nanoparticles functionalised with Co(II) coordination complexes at their surface show a significant increase of their magnetic anisotropy, leading to a doubling of the blocking temperature and a sixfold increase of the coercive field. Magnetometric studies suggest an enhancement that is not related to surface disordering, and point to a molecular effect involving magnetic exchange interactions mediated by the oxygen atoms at the interface as its source. Field- and temperature-dependent X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD) studies show that the magnetic anisotropy enhancement is not limited to surface atoms and involves the core of the nanoparticle. These studies also point to a mechanism driven by anisotropic exchange and confirm the strength of the magnetic exchange interactions. The coupling between the complex and the nanoparticle persists at room temperature. Simulations based on the XMCD data give an effective exchange field value through the oxido coordination bridge between the Co(II) complex and the nanoparticle that is comparable to the exchange field between iron ions in bulk maghemite. Further evidence of the effectiveness of the oxido coordination bridge in mediating the magnetic interaction at the interface is given with the Ni(II) analog to the Co(II) surface-functionalised nanoparticles. A substrate-induced magnetic response is observed for the Ni(II) complexes, up to room temperature