The Chemical modifications of condensed tannin by base-catalyzed reactions.

缩合单宁的有效利用开发是将无用树皮转化为有价值的资源所不可缺少的。然而，具有多酚特性的单宁还没有得到有效的利用。本研究通过碱催化反应使缩合单宁更均匀、更灵活，并讨论了碱变性处理对单宁亲核性和谷氨酸氨基转移酶抑制活性的影响。1)缩合单宁的制备及结构分析。研究了合成单宁的制备工艺，并对其作用机理进行了探讨。在此基础上，提出了香草醛-盐酸法、磷钼酸交换法和苯核交换法表征单宁的复合工艺。2)缩合单宁的碱催化化学改性。通过…的治疗在碱性较强的溶液中，单宁分子的转化率估计更高，但即使在温和的条件下，多酚的B环和A环也会被破坏。3)DSC用于分析加成反应、缩合反应和固化反应。通过对缩合单宁与甲醛反应的考察，得出缩合单宁应视为酚醛类物质的结论。因此，必须开发合适的分析复杂反应的技术，即加成、缩合和固化。为此，在HHO/H2O体系中应用高压差示扫描量热法(DSC)技术，发现反应放热与反应过程中的化学变化有很好的相关性。4)DSC对碱变性单宁的表征。DSC分析表明，碱催化变性处理是提高单宁活性的方法之一。5)碱变性单宁的谷氨酸氨基转移酶抑制活性。树皮单宁表现出较强的谷氨酸氨基转移酶抑制活性，但在严酷的碱处理条件下，使其专一性降低。这些行为表明，构成的苯核的邻近羟基模式强烈影响特异性。较少

Developments of useful usege for the condensed tannins are the indispensable for convert the useless barks into valuable resources. However, effective usages of the tannins having the polyphenolic characteristics have not been realized.This study was undertaken to make the condensed tannins more uniform and flexible polyphenol oligomers by the use of base-catalyzed reaction, and the effects of the denaturing treatment by alkali on the of nucleophilicity and GTase inhibitory activity of tannins were discussed.The results obtained were summarized below. 1) Preparations and structural analysis of condensed tannin. Appropriate techniques for preparing the synthesized tannins were developed and their mechanism was elucidated. Furthermore, the composite technique for charicterize the tannins were proposed by the use of vanillin-HCl, phosphomolybdic acid and pheny-nucleous exchange methods. 2) The chemical modification of condensed tannin by the base-catalyzed reactions. By the treatment with … More alkaline solutions, the tannin molecule was estimated to convert more flexible but B-ring of the polyphenols was destroyed as well as A-ring, even if the mild conditions were emplyed. 3) DSC for analysis of addition-, condensation- and curing-reactions. Through the examinations on the reaction with HCHO_<aq>., it was concluded that the condensed tannin have to regard as the novolak type materials. So the proper technique for analysis ot the complex reaction, that is addition, condensation and curing, had to be developed. For this purpose, DSC technique using high pressured cell was emplyed in the HCHO/H_2O system and the exothermic heat depended on the enthalpy changes during of the reaction with HCHO were recognized to nicely correlate with chemical change during the reactions. 4) Characterization of alkaline-denatured tannins by DSC.It was confirmed by the DSC examinations that the denaturing treatment by the base-catalyzed reaction was the one of the procedue to improve the reactivity of the tannin. 5) GTase inhibitory activity of alkaline-denatured tannins. Bark tannins exhibit strong GTase inhibitory activity, but alkaline treatment by the severe conditions caused for their specificity decreasing. These behavior suggests that the vicinal hydroxyl pattern of the constituted phenyl-nuclei affects the specificity strongly. Less