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Author:
Date:
2016-10-20
[Abstract] Condensed tannins extracted from plant tissues are suitable substitutes for phenolic resins. Their molecular structure, which might influence their chemical reactivity, can be assessed by the use of both HPLC-UV after acid thiolysis and MALDI-TOF mass spectrometry. Thiolysis of plant extracts in acidic methanol with cysteamine hydrochloride results in the release of the monomeric units of the condensed tannin oligomers that can be further quantified by reversed-phase HPLC-UV by comparison with analytical standards. MALDI-TOF mass spectrometry using 2,5-dihydroxybenzoic acid as matrix and K+ as cationization agent highlights the molecular structural characteristics (e.g., monomeric unit sequence) of the tannin oligomers. The methodologies permit the estimation of the ...
[摘要] 从植物组织提取的缩合单宁是酚醛树脂的合适替代物。它们的可能影响它们的化学反应性的分子结构可以通过在酸硫解和MALDI-TOF质谱之后使用HPLC-UV来评估。用半胱胺盐酸盐在酸性甲醇中溶解植物提取物导致缩合的单宁寡聚体的单体单元的释放，其可以通过与分析标准比较通过反相HPLC-UV进一步定量。使用2,5-二羟基苯甲酸作为基质和K sup +作为阳离子化试剂的MALDI-TOF质谱分析突出了单宁的分子结构特征（例如单体单元序列）低聚物。该方法允许估计平均和最大（可观察）聚合度，单体单元的类型和单宁单体的糖基化和/或酯化的存在。
[背景] 缩合单宁是由可从几种植物组织（例如软木树皮）中提取的黄烷-3-醇单体单元组成的多酚低聚物。它们已被认为是树脂配方（例如木材粘合剂和泡沫材料）中合成酚醛树脂的合适替代品。在缩合鞣酸中检测到的最常见的黄烷-3-醇单体，其羟基化模式和立体化学不同，如图1所示。
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图1.在缩合单宁结构中确定的最常见的单体
低聚物中单体单元的具体结构和聚合度强烈影响单宁的化学反应性和物理性质，例如与醛的缩合反应速率，重金属螯合能力和水溶液的粘度溶液（Pizzi和Stephanou，1994; ...
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