Neutral and acidic products derived from hydroxyl radical-induced oxidation of arabinotriose assessed by electrospray ionisation mass spectrometry


The oxidation of -(15)-l-arabinotriose (Ara(3)), an oligosaccharide structurally related to side chains of coffee arabinogalactans, was studied in reaction with hydroxyl radicals generated under conditions of Fenton reaction (Fe2+/H2O2). The acidic and neutral oxidation products were separated by ligand exchange/size-exclusion chromatography, subsequently identified by electrospray ionisation mass spectrometry (ESI-MS) and structurally characterised by tandem MS (ESI-MS/MS). In acidic fraction were identified several oxidation products containing an acidic residue at the corresponding reducing end of Ara(3), namely arabinonic acid, and erythronic, glyceric and glycolic acids formed by oxidative scission of the furanose ring. In neutral fractions were identified derivatives containing keto, hydroxy and hydroperoxy moieties, as well as derivatives resulting from the ring scission at the reducing end of Ara(3). In both acidic and neutral fractions, beyond the trisaccharide derivatives, the corresponding di- and monosaccharide derivatives were identified indicating the occurrence of oxidative depolymerisation. The structural characterisation of these oxidation products by ESI-MS/MS allowed the differentiation of isobaric and isomeric species of acidic and neutral character. The species identified in this study may help in detection of roasting products associated with the free radical-mediated oxidation of coffee arabinogalactans. Copyright (c) 2014 John Wiley & Sons, Ltd.



subject category

Biochemistry & Molecular Biology; Chemistry; Spectroscopy


Moreira, ASP; da Costa, EV; Evtuguin, DV; Coimbra, MA; Nunes, FM; Domingues, MRM

our authors


Thanks are due to Fundacao para a Ciencia e a Tecnologia (FCT, Portugal), European Union, QREN, FEDER and COMPETE for funding the QOPNA research unit (project PEst-C/QUI/UI0062/2013; FCOMP-01-0124-FEDER-037296), RNEM (REDE/1504/REM/2005 that concerns the Portuguese Mass Spectrometry Network) and Project PTDC/QUI-QUI/100044/2008. Ana S. P. Moreira thanks the PhD grant (SFRH/BD/80553/2011) also supported by funds from FCT.

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