An extracellular polysaccharide, N1, was obtained from the culture medium of the deep-sea fungus Aspergillus versicolor N2bc by a combination of ethanol precipitation, ion-exchange and gel filtration chromatography. N1 was a mannoglucogalactan with molecular weight of about 20.5kDa. Results of chemical and spectroscopic analyses, including Fourier-transform infrared, one- and two-dimensional nuclear magnetic resonance spectroscopy showed that the main chain of N1 consisted of →2)-α-d-Glcp-(1→, →2)-β-D-Glcp-(1→ and →6)-β-D-Manp-(1→ units, substituted at C-6 position of →2)-α-d-Glcp-(1→ units. The branches were composed of galactofuranose-oligosaccharides built up of →5)-β-D-Galf-(1→, →6)-β-D-Galf-(1→ and terminal β-D-Galf units. At an average, there were two branching points for every five sugar residues in the backbone. N1 possessed a high in vitro antioxidant activity as evaluated by scavenging assays involving superoxide, 1,1-diphenyl-2-picrylhydrazyl, hydroxyl radicals and reducing power. The investigation revealed that N1 was a novel antioxidant polysaccharide differing from previously described extracellular polysaccharides and could be a potential antioxidant.
NMR, extracellular polysaccharide, FTIR, antioxidant property, deep-sea fungus, Aspergillus versicolor N2bc
NCBI PubMed ID: 27178933Publication DOI: 10.1016/j.carbpol.2016.03.090Journal NLM ID: 8307156Publisher: Elsevier
Correspondence: Mao WJ
Institutions: Key Laboratory of Marine Drugs, Ministry of Education, Institute of Marine Drug and Food, Ocean University of China, Qingdao, China
Methods: 13C NMR, 1H NMR, IR, acid hydrolysis, FTIR, HPLC, UV, acetylation, TOCSY, methylation analysis, reduction with NaBH4, HPGPC, phenol-sulfuric acid assay, HMBC, radical scavenging assay, COSY, NOESY, HSQC, TFA hydrolysis
Found