Department of Plant Biotechnology, Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS), CSIC, Av. Reina Mercedes, 10, 41012-, Seville, Spain.
Centro de Estudos Florestais, Instituto Superior de Agronomia, Universidade de Lisboa, Tapada da Ajuda, 1349-017, Lisboa, Portugal.
ChemSusChem. 2020 Sep 7;13(17):4537-4547. doi: 10.1002/cssc.202000431. Epub 2020 Jun 2.
Lignins from different tree barks, including Norway spruce (Picea abies), eucalyptus (Eucalyptus globulus), mimosa (Acacia dealbata) and blackwood acacia (A. melanoxylon), are thoroughly characterized. The lignin from E. globulus bark is found to be enriched in syringyl (S) units, with lower amounts of guaiacyl (G) and p-hydroxyphenyl (H) units (H/G/S ratio of 1:26:73), which produces a lignin that is highly enriched in β-ether linkages (83 %), whereas those from the two Acacia barks have similar compositions (H/G/S ratio of ≈5:50:45), with a predominance of β-ethers (73-75 %) and lower amounts of condensed carbon-carbon linkages; the lignin from A. dealbata bark also includes some resorcinol-related compounds, that appear to be incorporated or intimately associated to the polymer. The lignin from P. abies bark is enriched in G units, with lower amounts of H units (H/G ratio of 14:86); this lignin is thus depleted in β-O-4' alkyl-aryl ether linkages (44 %) and enriched in condensed linkages. Interestingly, this lignin contains large amounts of hydroxystilbene glucosides that seem to be integrally incorporated into the lignin structure. This study indicates that lignins from tree barks can be seen as an interesting source of valuable phenolic compounds. Moreover, this study is useful for tailoring conversion technologies for bark deconstruction and valorization.
对来自不同树皮的木质素，包括挪威云杉（Picea abies）、桉树（Eucalyptus globulus）、金合欢（Acacia dealbata）和黑木相思（A. melanoxylon），进行了全面的表征。研究发现，桉树树皮中的木质素富含愈创木基（S）单元，而较少的松柏基（G）和对羟苯基（H）单元（H/G/S 比为 1:26:73），这导致木质素高度富含β-醚键（83%），而来自两种金合欢树皮的木质素具有相似的组成（H/G/S 比约为 5:50:45），以β-醚键为主（73-75%），缩合碳-碳键的含量较低；金合欢树皮中的木质素还包含一些与间苯二酚有关的化合物，这些化合物似乎被整合到聚合物中或与之密切相关。挪威云杉树皮中的木质素富含松柏基单元，较少的 H 单元（H/G 比为 14:86）；因此，这种木质素中β-O-4'烷基-芳基醚键的含量较低（44%），而缩合键的含量较高。有趣的是，这种木质素含有大量的羟基芪葡萄糖苷，它们似乎被完整地整合到木质素结构中。这项研究表明，来自树皮的木质素可以被视为有价值酚类化合物的一个有趣来源。此外，这项研究对于树皮解构和增值的转化技术的定制具有重要意义。
