Title
Elucidation of the structure of lignin and lignin carbohydrate complex of gramineae
Authors
LAN YAO HAITAO YANG JIAJUE XU NENG ZHANG YING CHEN and YIMIN XIE

Received September 3, 2013
Published Volume 49 Issue 3-4 March-April
Keywords lignin, lignin-carbohydrate complex, 13C-NMR, isotopic tracer

Abstract
In order to analyze the structure of lignin and lignin-carbohydrate complex of gramineae, 13C labeled coniferin was injected into living rice stalk. Milled wood lignin (MWL) and lignin carbohydrate complex (LCC) were extracted from rice stalk by the Björkman method. From the analysis of FT-IR and 13C-NMR spectra of MWL and LCC, it was found that the main linkage between lignin and polysaccharide was the benzyl ether bond. It was also possible that they were connected by an ester bond and an acetal bond. The main lignin structures were β-O-4, β-β, β-5 and β-1, with minor coniferyl alcohol. Then, LCC was treated by cellulase and hemicellulase to get enzyme degraded LCC (EDLCC). The parts dissolved and not dissolved in water were called EDLCC-WS and EDLCC-IS, respectively. From FT-IR and 13C-NMR analyses of EDLCC-WS and EDLCC-IS, it was concluded that the linkages between lignin and carbohydrate included a benzyl ether bond, an ester bond and an acetal bond.