Lignin-carbohydrate complexes containing phenolic acids isolated from the culms of bamboo.

Lignin-carbohydrate complexes containing phenolic acids (LCC-W) were isolated from Mosobamboo (Phyllostachys pubescens Mazel) and characterized. LCC-W was separated into three fractions (W-1, 2, and 3) by gel filtration on Sepharose 4B. Of these three LCCs W-2 and W-3 were included in the gel matrices. W-2 consists of 34.7% neutral sugar, 1.6% uronic acid, 52.1% lignin, and 6.1% phenolic acid, and W-3, 67.9%, 3.6%, 22.3%, and 1.1%, respectively. Neutral sugar residues of W-2 and W-3 were mainly L-arabinose and D-xylose in the ratios of 5.5:94.3 in W-2, and 4.5:95.0 in W-3, respectively. Methylation, periodate degradation, and NMR analyses indicated that the carbohydrate moiety of LCC-W is composed of a linear backbone of β-(1→4)-linked D-xylopyranose residues with approximately every thirty residues carrying one 4-O-methyl-Dglucuronic acid and one or two arabinofuranose residues. Saponified phenolic acids were composed of trans-p-coumanc and trans-fenilic acids, which seems to be esterified to carbohydrate and lignin, respectively. Alkaline treatment, periodate degradation, and hydrophobic interaction chromatography suggested the presence of alkali labile and stable lignin-carbohydrate linkages.