Oliveira Lúcia, Evtuguin Dmitry V, Cordeiro Nereida, Silvestre Armando J D, Silva Artur M S, Torres Isabel C
Department of Chemistry, University of Madeira, 9000-390 Funchal, Portugal.
J Agric Food Chem. 2006 Apr 5;54(7):2598-605. doi: 10.1021/jf0528310.
Dioxane lignin (DL) isolated from leaf sheaths of banana plant (Musa acuminata Colla var. cavendish) and in situ lignin were submitted to a comprehensive structural characterization employing spectroscopic (UV, FTIR, solid state 13C CP-MAS NMR, liquid state 13C and 1H NMR) and chemical degradation techniques (permanganate and nitrobenzene oxidation). Results obtained showed that banana plant leaf sheath lignin is of HGS type with a molar proportion of p-hydroxyphenyl (H)/guaiacyl (G)/syringyl (S) units of 12:25:63. Most of the H units in DL are terminal phenolic coumarates linked to other lignin substructures by benzyl and Cgamma-ester bonds in contrast to ferulates that are mainly ether linked to bulk lignin. It is proposed that banana plant leaf sheath lignin is chemically bonded to suberin-like components of cell tissues by ester linkages via essentially hydroxycinnamic acid residues. beta-O-4 structures (0.31/C6), the most abundant in DL, comprise mainly S units, whereas a significant proportion of G units is bonded by beta-5, 5-5', and 4-O-5' linkages contributing to ca. 80% of condensed structures in DL.
从香蕉植株（Musa acuminata Colla var. cavendish）叶鞘中分离得到的二氧六环木质素（DL）和原位木质素，采用光谱技术（紫外、傅里叶变换红外光谱、固态13C交叉极化魔角旋转核磁共振、液态13C和1H核磁共振）和化学降解技术（高锰酸盐和硝基苯氧化）进行了全面的结构表征。所得结果表明，香蕉植株叶鞘木质素属于HGS型，对羟基苯基（H）/愈创木基（G）/紫丁香基（S）单元的摩尔比例为12:25:63。与主要通过醚键连接到主体木质素上的阿魏酸酯不同，DL中大多数H单元是通过苄基和Cγ-酯键与其他木质素亚结构相连的末端酚类香豆酸酯。有人提出，香蕉植株叶鞘木质素通过基本上是羟基肉桂酸残基的酯键与细胞组织的类木栓质成分化学键合。β-O-4结构（0.31/C6）在DL中最为丰富，主要由S单元组成，而相当一部分G单元通过β-5、5-5′和4-O-5′键连接，占DL中缩合结构的约80%。
