title: Isolation, chemical characterization, and immunomodulatory activity of naturally acetylated hemicelluloses from bamboo shavings.
abstract: Bamboo shavings, the outer or intermediate layer of bamboo stems, are the bulk of by-products produced in bamboo processing. In this study we investigated the isolation, chemical characterization, and immunostimulatory activity in vitro of the hemicelluloses from bamboo shavings. Shavings were first pretreated by steam explosion. The optimal pretreatment was found to be steam explosion at 2.2 MPa for 1 min. Following this pretreatment, the yield of hemicelluloses reached (2.05±0.22)% (based on the dry dewaxed raw materials), which was 5.7-fold higher than that of untreated samples. Bamboo-shavings hemicellulose (BSH) was then prepared by hot water extraction and ethanol precipitation from the steam-exploded shavings. Purification of BSH by anion-exchange chromatography of diethylaminoethanol (DEAE)-sepharose Fast Flow resulted in a neutral fraction (BSH-1, purity of 95.3%, yield of 1.06%) and an acidic fraction (BSH-2, purity of 92.5%, yield of 0.79%). The weight-average molecular weights (Mw) of BSH-1 and BSH-2 were 12 800 and 11 300 g/mol, respectively. Chemical and structural analyses by Fourier transform infrared spectroscopy (FT-IR), 1D (1H and13C) and 2D (heteronuclear single quantum correlation (HSQC)) nuclear magnetic resonance (NMR) spectra revealed that BSH-1 was O-acetylated-arabinoxylan and BSH-2 was O-acetylated-(4-O-methylglucurono)-arabinoxylan. BSH-1 had a higher content of acetyl groups than BSH-2. For the immunomodulatory activity in vitro, BSH and BSH-2 significantly stimulated mouse splenocyte proliferation while BSH-1 had no effect; BSH, BSH-1, and BSH-2 markedly enhanced the phagocytosis activity and nitric oxide production of the murine macrophage RAW264.7 in a dose-dependent manner. Our results suggest that the water-extractable hemicelluloses from steam-exploded bamboo shavings are naturally acetylated and have immunostimulatory activity.
authors.affiliation: Department of Food Science and Nutrition, School of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310058, China.
authors.forename: Ju-Qing
authors.initials: JQ
authors.lastname: Huang
authors.affiliation: Department of Food Science and Nutrition, School of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310058, China.
authors.forename: Rui-Ting
authors.initials: RT
authors.lastname: Qi
authors.affiliation: Department of Food Science and Nutrition, School of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310058, China.
authors.forename: Mei-Rong
authors.initials: MR
authors.lastname: Pang
authors.affiliation: Department of Food Science and Nutrition, School of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310058, China.
authors.forename: Cong
authors.initials: C
authors.lastname: Liu
authors.affiliation: School of Public Health, Zhejiang University, Hangzhou 310058, China.
authors.forename: Guang-Yu
authors.initials: GY
authors.lastname: Li
authors.affiliation: Department of Food Science and Nutrition, School of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310058, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D000818:Animals; D049109:Cell Proliferation; D002845:Chromatography; D004305:Dose-Response Relationship, Drug; D000431:Ethanol / Q000737:chemistry; D004983:Ethanolamines / Q000737:chemistry; D005260:Female; D006863:Hydrogen-Ion Concentration; D008264:Macrophages / Q000187:drug effects* / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D051379:Mice; D008813:Mice, Inbred ICR; D008970:Molecular Weight; D009569:Nitric Oxide / Q000378:metabolism; D010587:Phagocytosis; D011134:Polysaccharides / Q000494:pharmacology*; D011312:Pressure; D031787:Sasa / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013154:Spleen / Q000166:cytology / Q000187:drug effects*; D013227:Steam
chemical_list: D004983:Ethanolamines; D011134:Polysaccharides; D013227:Steam; D009569:Nitric Oxide; D000431:Ethanol; C007916:hemicellulose; C007369:2-diethylaminoethanol
keywords: Bamboo shavings; Steam explosion pretreatment; Naturally acetylated hemicelluloses; Isolation; Chemical characterization; Immunomodulatory activity