Extraction and characterization of original lignin and hemicelluloses from wheat straw.
Original lignin and hemicelluloses were sequentially extracted with high yield/purity, using acidic dioxane/water solution and dimethyl sulfoxide, from ball-milled wheat straw. The acidic dioxane lignin fraction is distinguished by high beta-O-4' structures and by low amounts of condensed units (beta-5', 5-5', and beta-1'). Hemicelluloses contain arabinoxylans as the major polysaccharides, which are substituted by alpha-l-arabinofuranose, 4-O-methylglucuronic acid, acetyl group (DS = 0.1), and xylose at O-3 and/or O-2 of xylans. It was found that arabinoxylans form cross-links with lignins through ferulates via ether bonds, glucuronic acid via ester bonds, and arbinose/xylose via both ether and glycosidic bonds, respectively, in the cell walls of wheat straw. Diferulates are also incorporated into cross-links between lignin and hemicelluloses as well as lignification of wheat straw cell walls. The guaiacyl unit is considered to be a significant condensed structural constructor in extracted lignin and a connector between lignin and carbohydrates.
Sun
Xiao-Feng
XF
College of Forestry, North-Western Science and Technology University of Agriculture and Forestry, Yangling 712100, China.
Sun
RunCang
R
Fowler
Paul
P
Baird
Mark S
MS
D000447:Aldehydes / Q000032:analysis; D062385:Hydroxybenzoates / Q000032:analysis; D008031:Lignin / Q000737:chemistry / Q000302:isolation & purification*; D009682:Magnetic Resonance Spectroscopy; D008970:Molecular Weight; D011134:Polysaccharides / Q000737:chemistry / Q000302:isolation & purification*; D017550:Spectroscopy, Fourier Transform Infrared; D014908:Triticum / Q000737:chemistry*
D000447:Aldehydes; D062385:Hydroxybenzoates; D011134:Polysaccharides; C007916:hemicellulose; D008031:Lignin; C017616:phenolic acid