Extracellular polysaccharide with novel structure and antioxidant property produced by the deep-sea fungus Aspergillus versicolor N2bc

Abstract

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.

Keywords: 1,1-Diphenyl-2-picrylhydrazyl (PubChem CID: 2735032); 1-Phenyl-3-methyl-5-pyrazolone (PubChem CID: 90474051); Antioxidant property; Aspergillus versicolor N(2)bc; Butylated hydroxytoluene (PubChem CID: 31404); Deep-sea fungus; Dextran (PubChem CID: 5460037); Dichloromethane (PubChem CID: 6344); Dimethyl sulfoxide (PubChem CID: 679); Extracellular polysaccharide; FTIR; Iodomethane (PubChem CID: 6328); NMR; d-Galactose (PubChem CID: 6036); d-Glucose (PubChem CID: 5793); d-Mannose (PubChem CID: 18950).