College of Chemical Engineering, NanJing Forestry University, NanJing 210037, Jiangsu, China.
College of Chemical Engineering, NanJing Forestry University, NanJing 210037, Jiangsu, China.
Int J Biol Macromol. 2022 Feb 1;197:169-178. doi: 10.1016/j.ijbiomac.2021.12.144. Epub 2021 Dec 27.
The use of lignin is limited by its heterogeneity and complexity. This study was processed using different methods to obtain spruce milled wood lignin (SMWL), spruce kraft lignin (SKL), and spruce lignocresol (SLC) for comparative analysis of the structure and antioxidant activity. SMWL has a complete softwood lignin side-chains structure and lignin carbohydrate complexes. SKL contains fewer ether bonds, while more conjugate structures and condensed structures contribute to the color. However, the α-position of the lignin side chain eliminates most of the hydroxyl and ether bonds (β-O-4/α-OH, phenylcoumaran, and dibenzodioxocine structure) and effectively grafts p-cresol in the phase separation reaction. It not only inhibits the self-condensation of lignin, but also forms the 1,1-diarylpropane unit while protecting β-O-4 linkages from not breaking. Importantly, SLC has few conjugate structures that result in the lightest color among all lignin isolated. Besides, SLC has a high yield and contains trace carbohydrates, indicating that the phase separation method can achieve great amounts of purity separated lignin. The antioxidant activity of lignin was evaluated, results show that 85% of the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals were scavenged at the end of 60 min. Owing to its unique color, structural properties, and continuous antioxidant activity, SLC has the potential to manufacture antioxidant cosmetics.
木质素的使用受到其异质性和复杂性的限制。本研究采用不同的方法对云杉磨木木质素（SMWL）、云杉硫酸盐木质素（SKL）和云杉愈创木基木质素（SLC）进行处理，以比较它们的结构和抗氧化活性。SMWL 具有完整的软木木质素侧链结构和木质素碳水化合物复合物。SKL 中醚键较少，而更多的共轭结构和缩合结构导致颜色较深。然而，木质素侧链的α位消除了大部分羟基和醚键（β-O-4/α-OH、苯偶姻和二苯并二恶烷结构），并在相分离反应中有效接枝对甲酚。它不仅抑制了木质素的自缩合，而且在保护β-O-4 键不被破坏的同时形成 1,1-二芳基丙烷单元。重要的是，SLC 中几乎没有共轭结构，导致其颜色最浅。此外，SLC 产率高且碳水化合物含量低，表明相分离法可以实现大量高纯度分离木质素。评估了木质素的抗氧化活性，结果表明，在 60 分钟结束时，85%的 2,2-二苯基-1-苦基肼（DPPH）自由基被清除。由于其独特的颜色、结构特性和持续的抗氧化活性，SLC 有可能制造抗氧化化妆品。
