Understanding the regioselective hydrolysis of ginkgolide B under physiological environment based on generation, detection, identification, and semi-quantification of the hydrolyzed products
Understanding the regioselective hydrolysis of ginkgolide B under physiological environment based on generation, detection, identification, and semi-quantification of the hydrolyzed products
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基于水解产物的生成、检测、鉴定和半定量了解生理环境下银杏内酯B的区域选择性水解
DOI：
10.1007/s00216-015-8963-0
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发表时间：
2015-10-01
影响因子：
4.3
通讯作者：
Lan, Ke
中科院分区：
文献类型：
--
作者：
Li, Xue-Jing;Yang, Kui;Lan, Ke
采用液相色谱-质谱（LC-MS）联用技术，研究了银杏内酯B（GB）和银杏内酯A（GA）在生理环境中的水解情况。通过直接进样挥发性缓冲液中制备的样品，捕获快速水解过程。获得了水解产物的LC-MS行为，包括三个单羧酸和三个二羧酸。通过片段化分析鉴定了单羧酸酯，并相应地通过反应序列初步鉴定了二羧酸酯。GB和GA的碱催化水解的特征在于在4A ° C下在pH 7.0-10.7内。在pH6.8和7.4的热力学研究表明，对内酯-C和内酯-F的区域选择性反应。结果表明，GB骨架上的1-羟基阻断了内酯-E的反应性。基于这些结果，在人、大鼠和犬血浆中证实了GB的独特水解现象，即三内酯沿着快速降解，仅产生内酯-F-水解产物。这种现象也与1-羟基密切相关，因为在GA中没有观察到。更有趣的是，揭示了潜在的机制与任何典型的酶催化过程无关，但可能涉及血浆中完整或断裂的内酯-C部分与内源性小分子反应物的选择性反应。对银杏内酯和银杏内酯水解的深入了解不仅有助于理解其药理机制，而且为研究银杏内酯的构效关系提供了可能的途径。
A liquid chromatography-mass spectrometry (LC-MS) method coupled with specialized sample-preparation strategies was developed to investigate the hydrolysis of ginkgolide B (GB) in physiological environments in comparison with that of ginkgolide A (GA). The rapid hydrolysis processes were captured by the direct injection of samples prepared in the volatile buffers. The LC-MS behavior of the hydrolyzed products, including three monocarboxylates and three dicarboxylates, was acquired. The monocarboxylates were identified by fragmentation analysis, and the dicarboxylates were accordingly tentatively identified by reaction sequences. The base-catalyzed hydrolysis of GB and GA was characterized at 4 A degrees C within pH 7.0-10.7. The regioselective reactions on the lactone-C and lactone-F were revealed by thermodynamic studies at pH 6.8 and 7.4. It was revealed that the 1-hydroxyl group on the skeleton of GB blocks the reactivity of the lactone-E. On the basis of these results, a distinctive hydrolysis phenomenon of GB was confirmed in plasma of humans, rats, and dogs as a rapid degradation of the trilactone along with the only production of the lactone-F-hydrolyzed product. This phenomenon is also closely associated with the 1-hydroxyl group, because it was not observed in GA. More interestingly, the underlying mechanism was revealed not to be associated with any typical enzyme-catalyzed process, but to be potentially involved with a selective reaction of the intact or broken lactone-C moiety with endogenous small-molecule reactants in plasma. This in-depth knowledge of the hydrolysis of GB versus GA not only facilitated understanding of their pharmacological mechanisms but also provided potential routes to study the structure-activity relationships of ginkgolides.