John M, Gumbinger H G, Winterhoff H
Institut für Pharmakologie und Toxikologie, Westfälischen Wilhelms-Universität, Münster, Federal Republic of Germany.
Planta Med. 1990 Feb;56(1):14-8. doi: 10.1055/s-2006-960874.
Phenolic plant constituents exert antigonadotropic activity following an oxidation. The resulting complex mixture of mostly instable products impedes the elucidation of the various oxidation steps as well as the mode of antigonadotropic action. Thus caffeic acid was chosen as a single model phenolic to facilitate the interpretation. The oxidation of caffeic acid with KMnO4 as well as with polyphenoloxidase leads to the instable caffeic acid o-quinone as the first oxidation product. Following the initial oxidation, a number of products was indicated via HPLC. Two of them were isolated and characterized as oligomers of caffeic acid, one of them with phenolic, acid and, quinoic structural components and a relative molecular mass similar to caffeic acid tetramer. It was shown that caffeic acid quinone cannot be the antigonadotropically active principle. Correspondingly, the isolated oxidation products exhibit pronounced antigonadotropic activity. It could be proved that oxidation products of caffeic acid bind to PMSG, forming PMSG-inhibitor-complexes. In such complexes the gonadotropic activity of PMSG is completely abolished.
酚类植物成分在氧化后具有抗促性腺激素活性。由此产生的主要是不稳定产物的复杂混合物阻碍了对各种氧化步骤以及抗促性腺激素作用模式的阐明。因此，选择咖啡酸作为单一模型酚类以利于解释。用高锰酸钾以及多酚氧化酶氧化咖啡酸会产生不稳定的咖啡酸邻醌作为第一个氧化产物。初始氧化后，通过高效液相色谱法显示出多种产物。其中两种被分离出来并被鉴定为咖啡酸的低聚物，其中一种具有酚类、酸类和醌类结构成分，相对分子质量与咖啡酸四聚体相似。结果表明，咖啡酸醌不是具有抗促性腺激素活性的成分。相应地，分离出的氧化产物表现出明显的抗促性腺激素活性。可以证明，咖啡酸的氧化产物与孕马血清促性腺激素（PMSG）结合，形成PMSG - 抑制剂复合物。在这种复合物中，PMSG的促性腺激素活性被完全消除。
