Iron(II) binding by cereal beta-glucan

Faure, Audrey M.; Koppenol, Willem H.; Nyström, Laura

doi:10.1016/j.carbpol.2014.07.038

Cited by 13 publications

(7 citation statements)

References 17 publications

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“…Consequently, the removal of phytate made oat ␤-glucan very susceptible to Fenton reactioninduced oxidative degradation. This correlates to results by Faure et al (2015) who have shown that the Fenton reaction rate was slower in oat ␤-glucan than in barley ␤-glucan, subsequently less oxidative degradation was found in oat ␤-glucan. The results also concur with our previous study which showed that the oat ␤-glucan samples had better retardation of lipid oxidation and iron binding ability than barely ␤-glucan, and the differences were largely explained by the amount of phytate in the samples .…”

Section: Discussionsupporting

confidence: 92%

“…One main structural difference for oat and barley ␤-glucan is the DP3:DP4 ratio, which is higher for barley than for oats (Wood, Weisz, & Blackwell, 1994;Johansson, 2006). Faure, Koppenol, and Nyström (2015) have shown that oat ␤-glucan had a better iron binding ability than barley ␤-glucan which therefore reduced the hydroxyl radical formation and consequently hindered ␤-glucan oxidative degradation. Nonetheless, our recent study suggested that this difference may be related to the presence of residual phytate (myo-inositol-1,2,3,4,5,6-hexakis phosphate) rather than structural differences between ␤-glucan.…”

Section: Introductionmentioning

confidence: 99%

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The protective role of phytate in the oxidative degradation of cereal beta-glucans

Wang

Zhan

Sontag‐Strohm

et al. 2017

Carbohydrate Polymers

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Section: Discussionsupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

The protective role of phytate in the oxidative degradation of cereal beta-glucans

Wang

Zhan

Sontag‐Strohm

et al. 2017

Carbohydrate Polymers

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“…Although there is an abundance of literature about iron bioavailability in foods, only few studies investigate or discuss the role of the partly soluble dietary fibers such as β-glucan ( 24 , 25 , 40 , 65 ). However, it is nowadays an established fact that phytic acid plays a major role in the observed reduced bioavailability of the iron present in cereals and other vegetable food, as also confirmed by Wang et al ( 10 , 11 ).…”

Section: Resultsmentioning

confidence: 99%

“…Differences in iron-binding properties of commercial high-viscosity oat and barley β-glucan of high purity (>97%) were also assessed in a previous study ( 25 ). The kinetics of the Fenton reaction between iron(II) and hydrogen peroxide in 0.6% oat and barley β-glucan solutions at pH values 2.7 and 4.7 were measured.…”

Section: Introductionmentioning

confidence: 99%

Estimation of Iron Availability in Modified Cereal β-Glucan Extracts by an in vitro Digestion Model

et al. 2022

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For cereal-based foods rich in dietary fibers, iron bioavailability is known to be poor. For native cereal β-glucan extracts, literature has demonstrated that the main factor impacting the bioavailability is phytic acid, which is often found in association with dietary fibers. During food processing, β-glucan can undergo modifications which could potentially affect the equilibrium between phytic acid, fiber, and iron. In this study, an in vitro digestion was used to elucidate the iron dialysability, and hence estimate iron availability, in the presence of native, chelating resin (Chelex)-treated, oxidised, or partially hydrolysed oat and barley β-glucan extracts (at 1% actual β-glucan concentration), with or without phytase treatment. It was confirmed that pure, phytic acid-free β-glucan polysaccharide does not impede iron availability in cereal foods, while phytic acid, and to a smaller extent, also proteins, associated to β-glucan can do so. Neither Chelex-treatment nor partial hydrolysis, 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO) or NaIO4 oxidation significantly influenced the phytic acid content of the β-glucan extracts (ranging 2.0–3.9%; p > 0.05). Consequently, as long as intrinsic phytic acid was still present, the β-glucan extracts blocked the iron availability regardless of source (oat, barley) or Chelex-treatment, partial hydrolysis or NaIO4-oxidation down to 0–8% (relative to the reference without β-glucan extract). Remarkably, TEMPO-oxidation released around 50% of the sequestered iron despite unchanged phytic acid levels in the modified extract. We propose an iron-mobilising effect of the TEMPO product β-polyglucuronan from insoluble Fe(II)/phytate/protein aggregates to soluble Fe(II)/bile salt units that can cross the dialysis membrane. In addition, Chelex-treatment was identified as prerequisite for phytase to dramatically diminish iron retention of the extract for virtually full availability, with implications for optimal iron bioavailability in cereal foods.

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“…The kinetic studies of the Fenton reaction of Faure et al in oat or barley BG solutions also showed that commercial oat BG slows down the Fenton reaction at pH 4.7 (120 M −1 s −1 ) compared to barley BG (220 M −1 s −1 ) or acetate buffer (280 M −1 s −1 ). 50 Interestingly, this complexation influence could not be observed with the oligomer model compounds, suggesting that all three bind iron similarly regardless of their monomer connectivity.…”

Section: Kinetics Of the Oxidative Degradation Of Bg Oligosaccharidesmentioning

confidence: 97%

UPLC-MS/MS investigation of β-glucan oligosaccharide oxidation

Boulos

Nyström

2016

Analyst

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Polysaccharide degradation mediated by hydroxyl radicals (HO˙) or lytic monooxygenases (LPMOs) is relevant in various biological and industrial processes. Thereby, the Fenton-induced (HO/Fe) oxidation of mixed-linkage (1→3,1→4)-β-d-glucan (BG), a cereal dietary fibre with several well-established health promoting properties, shows potential for modulating BG functionality. The precise identification of oxidation products, however, is impeded by their diversity due to the indiscriminate nature of HO˙, the large molecular weight, and the corresponding low frequency of discrete alterations along the polymer chain. In this paper, we studied the Fenton-induced degradation of several constitutionally isomeric glucotetraoses as BG model compounds by hydrophilic interaction UPLC-MS/MS in negative ion, high resolution mode. The influence of the β-(1→3)-linkage on the reaction was investigated with regard to degradation kinetics, formation of products, and MS/MS fragmentation patterns. The position and occurrence of a β-(1→3)-bond had no influence on the degradation kinetics. Classification into primary and secondary acidic oxidation products by monitoring their progress over time is also demonstrated, implying complexation of primary aldonic acid products by the catalytic iron and subsequently facilitated site-specific secondary oxidation, underlining the metal's importance beyond its role as HO˙-generating catalyst. Similarly to oxidations mediated by certain LPMOs, thorough MS/MS-analysis of selected products and comparison with synthesised standards confirmed two types of glycosidic cleavage cascades induced by HO˙-mediated H-atom abstraction at C1 and C3/C4, producing gluconic acids, native oligosaccharides, and oxo-oligomers (carbonyl at non-reducing end). Additionally, systematic study of other oxo-products from the different isomers and rationalisation of MS/MS fragmentation mechanisms allowed for the identification of potentially diagnostic fragment signals for oxidised cereal BG.

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Iron(II) binding by cereal beta-glucan

Cited by 13 publications

References 17 publications

The protective role of phytate in the oxidative degradation of cereal beta-glucans

The protective role of phytate in the oxidative degradation of cereal beta-glucans

Estimation of Iron Availability in Modified Cereal β-Glucan Extracts by an in vitro Digestion Model

UPLC-MS/MS investigation of β-glucan oligosaccharide oxidation

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