title: Alginate oligosaccharides: enzymatic preparation and antioxidant property evaluation.
abstract: Alginate oligosaccharides (AOs) prepared from alginate, by alginate lyase-mediated depolymerization, were structurally characterized by mass spectrometry, infrared spectrometry and thin layer chromatography. Studies of their antioxidant activities revealed that AOs were able to completely (100%) inhibit lipid oxidation in emulsions, superiorly to ascorbic acid (89% inhibition). AOs showed radical scavenging activity towards ABTṠ, hydroxyl, and superoxide radicals, which might explain their excellent antioxidant activity. The radical scavenging activity is suggested to originate mainly from the presence of the conjugated alkene acid structure formed during enzymatic depolymerization. According to the resonance hybrid theory, the parent radicals of AOs are delocalized through allylic rearrangement, and as a consequence, the reactive intermediates are stabilized. AOs were weak ferrous ion chelators. This work demonstrated that AOs obtained from a facile enzymatic treatment of abundant alginate is an excellent natural antioxidant, which may find applications in the food industry.
authors.affiliation: Department of Engineering, Aarhus University, Gustav Wiedsvej 10C, DK-8000 Aarhus C, Denmark.
authors.forename: Mia
authors.initials: M
authors.lastname: Falkeborg
authors.affiliation: Department of Engineering, Aarhus University, Gustav Wiedsvej 10C, DK-8000 Aarhus C, Denmark.
authors.forename: Ling-Zhi
authors.initials: LZ
authors.lastname: Cheong
authors.affiliation: Department of Engineering, Aarhus University, Gustav Wiedsvej 10C, DK-8000 Aarhus C, Denmark; Department of Biology, Università di Roma Tor Vergata, Via della Ricerca Scientifica 1, 00133 Rome, Italy.
authors.forename: Carlo
authors.initials: C
authors.lastname: Gianfico
authors.affiliation: Department of Engineering, Aarhus University, Gustav Wiedsvej 10C, DK-8000 Aarhus C, Denmark.
authors.forename: Katarzyna Magdalena
authors.initials: KM
authors.lastname: Sztukiel
authors.affiliation: Department of Chemistry and iNANO, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C, Denmark.
authors.forename: Kasper
authors.initials: K
authors.lastname: Kristensen
authors.affiliation: Department of Chemistry and iNANO, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C, Denmark.
authors.forename: Marianne
authors.initials: M
authors.lastname: Glasius
authors.affiliation: Department of Engineering, Aarhus University, Gustav Wiedsvej 10C, DK-8000 Aarhus C, Denmark.
authors.forename: Xuebing
authors.initials: X
authors.lastname: Xu
authors.affiliation: Department of Engineering, Aarhus University, Gustav Wiedsvej 10C, DK-8000 Aarhus C, Denmark. Electronic address: guo@mb.au.dk.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Guo
mesh_terms: D000464:Alginates / Q000737:chemistry*; D000975:Antioxidants / Q000737:chemistry*; D001205:Ascorbic Acid / Q000737:chemistry; D016166:Free Radical Scavengers / Q000737:chemistry; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry; D007502:Iron Chelating Agents; D008055:Lipids / Q000737:chemistry; D015394:Molecular Structure; D009844:Oligosaccharides / Q000737:chemistry*; D010084:Oxidation-Reduction; D011133:Polysaccharide-Lyases / Q000737:chemistry*
chemical_list: D000464:Alginates; D000975:Antioxidants; D016166:Free Radical Scavengers; D006603:Hexuronic Acids; D007502:Iron Chelating Agents; D008055:Lipids; D009844:Oligosaccharides; D020723:Glucuronic Acid; D011133:Polysaccharide-Lyases; C016158:poly(beta-D-mannuronate) lyase; D001205:Ascorbic Acid
keywords: Alginate lyase; Alginate oligosaccharides; Ferrous ion chelation; Natural antioxidants; Radical scavenging