Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS), CSIC , PO Box 1052, E-41080 Seville, Spain.
J Agric Food Chem. 2013 Mar 13;61(10):2434-45. doi: 10.1021/jf304686x. Epub 2013 Feb 26.
The structure of the isolated milled "wood" lignin from coconut coir has been characterized using different analytical methods, including Py-GC/MS, 2D NMR, DFRC, and thioacidolysis. The analyses demonstrated that it is a p-hydroxyphenyl-guaiacyl-syringyl (H-G-S) lignin, with a predominance of G units (S/G ratio 0.23) and considerable amounts of associated p-hydroxybenzoates. Two-dimensional NMR indicated that the main substructures present in this lignin include β-O-4' alkyl aryl ethers followed by phenylcoumarans and resinols. Two-dimensional NMR spectra also indicated that coir lignin is partially acylated at the γ-carbon of the side chain with p-hydroxybenzoates and acetates. DFRC analysis showed that acetates preferentially acylate the γ-OH in S rather than in G units. Despite coir lignin's being highly enriched in G-units, thioacidolysis indicated that β-β' resinol structures are mostly derived from sinapyl alcohol. Finally, we find evidence that the flavone tricin is incorporated into the coconut coir lignin, as has been recently noted for various grasses.
采用不同的分析方法，包括 Py-GC/MS、二维 NMR、DFRC 和硫代酸解，对从椰子纤维中分离得到的研磨“木质素”的结构进行了表征。分析表明，它是一种 p-羟基苯基-愈创木基-丁香基（H-G-S）木质素，G 单元居多（S/G 比为 0.23），并含有相当数量的相关对羟基苯甲酸酯。二维 NMR 表明，该木质素中存在的主要亚结构包括β-O-4'烷基芳基醚，其次是苯并呋喃和树脂醇。二维 NMR 谱还表明，椰子纤维木质素在侧链的γ-碳上与对羟基苯甲酸酯和乙酸酯部分酰化。DFRC 分析表明，乙酸酯优先酰化 S 单元而不是 G 单元的 γ-OH。尽管椰子纤维木质素高度富含 G 单元，但硫代酸解表明 β-β'树脂醇结构主要来源于松柏醇。最后，我们发现黄酮类化合物tricetin 被整合到椰子纤维木质素中，这在最近各种草类中也有报道。
