Fractionation, characterization and antioxidant activity of exopolysaccharides from fermentation broth of a Cordyceps sinensis fungus

Qi Lin Huang, Ka Chai Siu, Wen Qiang Wang, Yi Ching Cheung, Jianyong Wu

Research output: Journal article publicationJournal articleAcademic researchpeer-review

65 Citations (Scopus)

Abstract

Exopolysaccharide (EPS) fractions P1/5, P2/5, P1, P2and P5were isolated from the fermentation medium of a medicinal fungus Cordyceps sinensis by gradient precipitation with ethanol at 1/5, 2/5, 1, 2, and 5 volume ratios to the liquid medium. P1/5and P2/5were mainly composed of polysaccharides with negligible protein content and a large molecular or particle size (intrinsic viscosity [η] 2025 mL/g; hydrodynamic radius Rh905 nm). The fraction attained at a higher ethanol volume ratio had a much higher protein and lower carbohydrate content, and a smaller molecular size. In particular, P5was composed of mainly protein with an average molecular weight 16 kDa, [η] 4.3 mL/g and Rh23.5 nm. The antioxidant activities of EPS fractions showed a significant dependence on the protein content, being negligible of P1/5and P2/5, low to moderate of P1and P2, and very strong of P5. Gradient ethanol precipitation was proven a simple and workable method for initial fractionation of polysaccharides, proteins and their complexes with different molecular sizes and for further identification of the bioactive components.
Original languageEnglish
Pages (from-to)380-386
Number of pages7
JournalProcess Biochemistry
Volume48
Issue number2
DOIs
Publication statusPublished - 1 Feb 2013

Keywords

  • Antioxidant activity
  • Cordyceps sinensis
  • Ethanol precipitation
  • Liquid fermentation
  • Polysaccharide-protein complex

ASJC Scopus subject areas

  • Biochemistry
  • Applied Microbiology and Biotechnology
  • Bioengineering

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