Revealing the structure-activity relationship between lignin and anti-UV radiation
Revealing the structure-activity relationship between lignin and anti-UV radiation
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揭示木质素与抗紫外线辐射之间的构效关系
DOI：
10.1016/j.indcrop.2021.114212
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发表时间：
2021-10-30
影响因子：
5.9
通讯作者：
Lu, Fachuang
中科院分区：
文献类型：
--
作者：
Lin, Minsheng;Yang, Linjie;Lu, Fachuang
木质素是一种丰富的天然可再生芳香族聚合物，是一种良好的紫外线吸收剂和天然广谱防晒剂。由于木质素的复杂性和异质性，紫外辐射下木质素的构效关系尚不清楚。本文报道了木质素的结构对其防晒系数（SPF）、紫外吸光度和抗氧化活性等抗紫外辐射性能的影响，采用不同的木质素模型化合物，包括0-O-4、0-0和0-5二聚体等，代表天然木质素和工业木质素的结构。同时，对思茅松和桉树的纤维素酶木质素（CEL）、有机溶剂木质素（OL）和硫酸盐木质素（KL）等6种木质素制备物的紫外防护性能进行了评价，以便更好地进行比较。防晒制剂的SPF值增加，但随着将每种单一模型化合物相同地添加到纯霜或商业防晒剂中而变化。特别地，通过将一定摩尔浓度的单一模型化合物（0.0558mmol，约2wt%）添加到低SPF市售防晒剂中，防晒剂的SPF值已经大大提高，这归因于木质素模型和固有防晒剂的协同效应。通过比较发现，含0-O-4键的木质素模型化合物的紫外防护性能最差，而侧链的差异，尤其是共轭结构和羧基的存在，会显著影响木质素模型化合物的紫外防护性能。此外，不同模型化合物和木质素制剂的抗氧化活性和紫外吸光度与其结构密切相关。这些发现揭示了木质素在紫外光照射下的构效关系，为优化木质素或木质素衍生物作为防晒剂提供了理论依据。
As a highly abundant natural and renewable aromatic polymer, lignin has been proven to be a good UV-absorber and natural broad-spectrum sun blocker. The structure-activity relationship of lignin under UV radiation remains unclear due to lignin's complexity and heterogeneity. Here we report the structure influence of lignin on its antiUV radiation properties of sun protection factor (SPF), UV absorbance, and antioxidant activity by using different lignin model compounds, including 0-O-4, 0-0, and 0-5 dimers, etc., representing the structures of both native lignins and technical lignins. Meanwhile, UV protection properties of six lignin preparations, including cellulolytic enzyme lignin (CEL), organosolv lignin (OL), and kraft lignin (KL) of pinus kesiya and eucalyptus, were also evaluated for better comparison. SPF values of sunscreen preparations were increased but varied with the same addition of each single model compound into the pure cream or commercial sunscreen. In particular, the SPF value of the sunscreen has been greatly enhanced by the addition of a certain molar concentration of a single model compound (0.0558 mmol, around 2 wt%) into the low SPF commercial sunscreen, which was attributed to the synergistic effects of lignin models and inherent sunscreen agent. By comparing, lignin models containing 0-O-4 linkage displayed the least desirable UV protection properties in this work, and side-chain difference, especially the existence of conjugate structure and carboxylic groups, would significantly impact the lignin model compounds' UV performance. Additionally, the antioxidant activities and UV absorbance of different model compounds and lignin preparations are closely related to their structures. These insights revealed the structure-activity relationship of lignin under UV radiation and will provide a theoretical basis for optimizing lignins or lignin derivatives as the sun-screening agents in sunscreens.