Oxidation of amylose and amylopectin by hydroxyl radicals assessed by electrospray ionisation mass spectrometry

resumo

The hydroxyl radicals (HO center dot) are one of the most reactive oxygen species (ROS) involved in the oxidative damage of biological molecules, including carbohydrates. During the industrial processing of food, ROS can be formed. In order to identify the structural changes induced in starch by oxidation, amylose, amylopectin, and maltotriose, an oligosaccharide structurally related to these polysaccharides, were subjected to oxidation with HO center dot generated under Fenton reaction conditions (Fe2+/H2O2). The oxidised polysaccharides were hydrolysed by alpha-amylase and the obtained oligosaccharides were fractionated by ligand-exchange/size-exclusion chromatography. Both acidic and neutral alpha-amylase resistant oligosaccharides were characterized by mass spectrometry. In oxidised neutral products, new keto, hydroxyl, and hydroperoxy moieties, and oxidative ring scission were observed at the reducing end of the oligosaccharides. The acid sugar residues occurred at the reducing end and included gluconic and glucuronic acid derivatives, and acids formed by oxidative ring scission, namely, arabinonic, erythronic, glyceric and glycolic acids. (C) 2016 Elsevier Ltd. All rights reserved.

palavras-chave

STARCH; POLYSACCHARIDES; DISACCHARIDES; OLIGOSACCHARIDES; DIFFERENTIATION; ARABINOTRIOSE; HYPOCHLORITE; PRODUCTS

categoria

Chemistry; Polymer Science

autores

Simoes, J; Moreira, ASP; da Costa, E; Evtyugin, D; Domingues, P; Nunes, FM; Coimbra, MA; Domingues, RM

nossos autores

agradecimentos

Thanks are due to Fundacao para a Ciencia e a Tecnologia FCT/MEC Portugal for the financial support to the QOPNA research Unit (FCT UID/QUI/00062/2013), through national founds and where applicable co-financed by the FEDER, within the PT2020 Partnership Agreement, and RNEM (REDE/1504/REM/2005 that concerns the Portuguese Mass Spectrometry Network). Thanks are also due to FCT for the grant of Joana Simoes (SFRH/BPD/90447/2012).

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