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A comb-like branched β-d-glucan produced by a Cordyceps sinensis fungus and its protective effect against cyclophosphamide-induced immunosuppression in mice

Hu, Ting, Jiang, Chenbo, Huang, Qilin, Sun, Fengyuan
Carbohydrate polymers 2016 v.142 pp. 259-267
Fourier transform infrared spectroscopy, Ophiocordyceps sinensis, acid hydrolysis, beta-glucans, ethanol, exopolysaccharides, fermentation, fungi, gas chromatography-mass spectrometry, glucose, immunosuppression, interferon-gamma, mannose, methylation, mice, models, nuclear magnetic resonance spectroscopy, oxidation, protective effect, tumor necrosis factor-alpha, viscosity
An exopolysaccharide (EPS) was fractionated from fermentation media of a Cordyceps sinensis fungus (Cs-HK1) by ethanol precipitation at 2/5 volume ratio of ethanol/media. Its structural characteristics were elucidated by FT-IR, GC, GC–MS, 1D and 2D NMR combined with periodate oxidation, Smith degradation, partial acid hydrolysis, and methylation analysis. Furthermore, the immunomodulatory activity of EPS was evaluated by the model of cyclophosphamide-induced immunosuppression. The results from monosaccharide composition and partial acid hydrolysis indicated that EPS almost consisted of glucose excluding a trace amount of mannose. GC–MS and NMR analysis further confirmed EPS had a linear backbone of (1→3)-β-d-glucopyranosyl residues with a single (1→6)-β-d-glucopyranosyl side-branching unit for every three β-d-glucopyranosyl residues, showing a comb-like β-d-glucan with short and intensive branches, which was responsible for high viscosity. Moreover, EPS could significantly enhance immune organs and stimulate the release of major cytokines TNF-α and INF-γ, suggesting that EPS exhibited protective effect in immunocompromised mice.