title: Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry analysis of oligosaccharides and oligosaccharide alditols obtained by hydrolysis of agaroses and carrageenans, two important types of red seaweed polysaccharides.
abstract: MALDI-TOF mass spectrometry analyses of several oligosaccharides (aldoses) and oligosaccharide alditols derived from agaroses, kappa- and iota-carrageenans using different matrices (2,5-dihydroxybenzoic acid, nor-harmane, ferulic acid, and the ionic liquid matrices 2,5-dihydroxybenzoic acid-n-butylamine and ferulic acid-n-butylamine) were conducted. These carbohydrates were selected as model compounds to study the MALDI prompt and post-source decay (PSD) fragmentation processes of both families of oligosaccharides. Sulfated alditols showed in the negative-ion mode the molecular ion as [M-Na](-) together with the species yielded by their prompt fragmentation (mainly desulfation) while the sulfated oligosaccharides (aldoses) showed mainly glycosidic prompt fragmentation (glycosidic C-cleavages and desulfation). Non-sulfated aldoses and alditols, which could only be analyzed in positive-ion mode ([M+Na](+)), did not suffer any prompt fragmentation. The former yielded cross-ring fragmentation in the PSD mode. Best results were obtained by using 2,5-dihydroxybenzoic acid and/or nor-harmane as matrices for all the compounds studied.
authors.affiliation: The United Graduate School of Agricultural Sciences, Faculty of Agriculture, Ehime University, 3-5-7-Tarumi, Matsuyama 790-8566, Japan.
authors.forename: M Kaniz
authors.initials: MK
authors.lastname: Fatema
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nonami
authors.forename: Diogo R B
authors.initials: DR
authors.lastname: Ducatti
authors.forename: Alan G
authors.initials: AG
authors.lastname: Gonçalves
authors.forename: M Eugenia R
authors.initials: ME
authors.lastname: Duarte
authors.forename: Miguel D
authors.initials: MD
authors.lastname: Noseda
authors.forename: Alberto S
authors.initials: AS
authors.lastname: Cerezo
authors.forename: Rosa
authors.initials: R
authors.lastname: Erra-Balsells
authors.forename: María C
authors.initials: MC
authors.lastname: Matulewicz
mesh_terms: D002351:Carrageenan / Q000737:chemistry*; D006868:Hydrolysis; D007202:Indicators and Reagents / Q000737:chemistry; D009844:Oligosaccharides / Q000032:analysis* / Q000737:chemistry*; D012624:Seaweed / Q000737:chemistry*; D012685:Sepharose / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013402:Sugar Alcohols / Q000032:analysis* / Q000737:chemistry*
chemical_list: D007202:Indicators and Reagents; D009844:Oligosaccharides; D013402:Sugar Alcohols; D002351:Carrageenan; D012685:Sepharose