title: Structural features and antioxidant activities of lignins from steam-exploded bamboo (Phyllostachys pubescens).
abstract: An environmentally friendly steam explosion process of bamboo, followed by alkali and alkaline ethanol delignification, was developed to fractionate lignins. Results showed that after steam explosion the lignins isolated showed relatively low carbohydrate contents (0.55-1.76%) and molecular weights (780-1050 g/mol). For each steam-exploded sample, alkali-extracted lignins presented higher phenolic OH values (1.41-1.82 mmol/g), p-coumaric acid to ferulic acid ratios (pCA/FA ratios 4.5-14.1), and syringyl to guaiacyl ratios (S/G ratios 5.0-8.5) than those from alkaline ethanol-extracted lignins (phenolic OH 0.85-1.35 mmol/g, pCA/FA ratios 1.6-5.2, and S/G ratios 3.5-4.8). The lignins obtained consisted mainly of β-O-4' linkages combined with small amounts of β-β', β-5', and α-O-4/β-O-4 linkages. Antioxidant activities of the lignins obtained were tested by the 2,2-diphenyl-1-picrylhydrazyl, 2,2'-azobis(3-ethylbenzothiazoline-6-sulfonic acid), and ferric reducing activity power methods. It was found that alkali-extracted lignins obtained during the initial extraction process had higher antioxidant activities than alkaline ethanol-extracted lignins obtained during the second extraction process.
authors.affiliation: Beijing Key Laboratory of Lignocellulosic Chemistry, Beijing Forestry University , Beijing 100083, China.
authors.forename: Shao-Ni
authors.initials: SN
authors.lastname: Sun
authors.forename: Xue-Fei
authors.initials: XF
authors.lastname: Cao
authors.forename: Feng
authors.initials: F
authors.lastname: Xu
authors.forename: Run-Cang
authors.initials: RC
authors.lastname: Sun
authors.forename: Gwynn Lloyd
authors.initials: GL
authors.lastname: Jones
mesh_terms: D000975:Antioxidants / Q000737:chemistry* / Q000302:isolation & purification; D001709:Biotechnology; D008031:Lignin / Q000737:chemistry* / Q000302:isolation & purification; D015394:Molecular Structure; D008970:Molecular Weight; D010936:Plant Extracts / Q000737:chemistry* / Q000302:isolation & purification; D006109:Poaceae / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013227:Steam
chemical_list: D000975:Antioxidants; D010936:Plant Extracts; D013227:Steam; D008031:Lignin