巨菌草纤维特性分析及其木素结构表征

Fiber Morphology, Lignin Structure and Lignin Distribution in Cell Wall of the Pennisetumsinese

关键词:  巨菌草  木素结构  核磁共振磷谱  二维核磁共振

Key Words:Pennisetumsinese  lignin structure  31P-NMR  2D-HSQC NMR

摘要:对巨菌草纤维形态、化学成分组成、木素结构及其微区分布进行了研究。利用纤维质量分析仪（FQA）测得纤维平均长度为0.95 mm，宽度为23.1 μm，长宽比为41.1。高效液相色谱（HPLC）定量分析碱性硝基苯氧化产物确定巨菌草木素结构为典型的GSH型。利用核磁共振磷谱（31P-NMR）定量分析木素各酚羟基功能基团，结果显示脂肪族羟基含量最高，为3.96 mmol/g，其中非缩合型羟基占总酚羟基的比例较大，为96.3%；二维核磁共振（2D-HSQC NMR）波谱分析表明，β-O-4′芳基醚键结构比例最高，为84.4%；其次为β-β′树脂醇结构和β-5′苯基香豆满结构，所占比例分别为9.9%和5.7%；在芳香区含有大量的紫丁香基和愈创木基结构单元，其中S/G比例为1.25。共聚焦拉曼光谱（CRM）分析表明，木素在细胞不同区域的浓度由大到小的顺序为细胞角隅CC＞复合胞间层CML＞次生细胞壁SW；羟基肉桂酸的浓度分布规律与木素的分布变化相似，但其浓度低于木素的浓度。

Abstract:The morphologiy of fibers, chemical components, lignin structure and the lignin distribution in cell wall of Pennisetumsinese were analyzed. Fiber Quality Analyzer (FQA) analysis showed that average fiber length was 0.96mm and the width was 23.1 μm, fiber length-width ratio reached to 41.1. Alkaline nitrobenzene oxidation quantitative analysis revealed that Pennisetumsinese lignin was typical GSH-type. It was found that the highest content of hydroxyl groups was aliphatic OH (3.96 mmol/g), and non-condensed phenolic hydroxyl accounted for a large proportion content of the total phenolic hydroxyl (96.3%). In addition, 2D-HSQC NMR analysis indicated that the alkyl aryl ether linkages was predominant (β-O-4′, 84.4% of total linkages), followed by resinols (β-β′, 9.9%) and phenylcomumarans (β-5′5.7%). Moreover, aromatic regions showed large quantity of S-type and G-type lignin, and the S/G ratio was 1.25. Confocal Raman microscopy (CRM) indicated that the concentrations of lignin and hydroxycinnamic acid (HCA) in the cell walls followed the decreasing order, as CC＞CML＞SW, but the concentration of HCA waslowerthan that of lignin.