Alginate oligosaccharides: Enzymatic preparation and antioxidant property evaluation

•Alginate lyase S can depolymerize alginate into alginate oligosaccharides (AOs).•AOs were structurally identified as a mixture of dimers, trimers, and tetramers.•AOs showed better antioxidant activity than Vc and other poly/monomeric alginates.•Conjugated alkene acid structure in AOs enhanced their...

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Veröffentlicht in:Food chemistry 2014-12, Vol.164, p.185-194
Hauptverfasser: Falkeborg, Mia, Cheong, Ling-Zhi, Gianfico, Carlo, Sztukiel, Katarzyna Magdalena, Kristensen, Kasper, Glasius, Marianne, Xu, Xuebing, Guo, Zheng
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Sprache:eng
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Zusammenfassung:•Alginate lyase S can depolymerize alginate into alginate oligosaccharides (AOs).•AOs were structurally identified as a mixture of dimers, trimers, and tetramers.•AOs showed better antioxidant activity than Vc and other poly/monomeric alginates.•Conjugated alkene acid structure in AOs enhanced their radical scavenging activity.•Alginate and AOs displayed very low ferrous ion chelating activities. 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.
ISSN:0308-8146
1873-7072
DOI:10.1016/j.foodchem.2014.05.053