Neuromodulatory Effects of Ginkgolides and Bilobalide

描述(由申请人提供)：本提案的重点是银杏叶中银杏内酯和白果内酯(萜内酯)的作用方式。银杏的粗提物是一种由许多不同化合物组成的复杂混合物，对哺乳动物大脑的疾病和健康状态都有影响。临床研究、动物研究和各种体外研究表明，这些提取物对各种神经退行性疾病，特别是阿尔茨海默病有有益的作用，以及在正常大脑中具有增强记忆的作用。然而，关于单个成分的影响，特别是在分子结构水平上的影响，人们知之甚少。在这项提案中，我们将重点关注银杏叶提取物中最独特的成分，银杏内酯和白果内酯，而不是粗提物的作用，因为粗提物明显涉及协同作用，例如，在黄酮类(主要成分)和萜类三内酯之间。一些银杏内酯是血小板激活因子受体(PAFR)的拮抗剂，似乎具有抗氧化和神经保护特性。我们还发现银杏内酯B是一种甘氨酸受体拮抗剂，而白果内酯是一种有效的GABAA受体拮抗剂。我们的目标是利用生物有机学和光谱方法，包括我们实验室正在开发的那些分子水平的方法，来确定萜三酮对哺乳动物中枢神经系统的神经调节作用。将研究的具体课题包括用于正电子发射断层扫描(PET)和体外放射自显影研究的放射性示踪剂的合成，用于阐明萜三酮和PAFR相互作用的新型耐光性和荧光性萜三酮类似物的设计和制备。在这些研究中，我们将开发和应用新的方法，如使用非传统质谱学和圆二色谱技术的超微尺度光标记和测序，以及“膜剪刀”。利用放射配基结合和微生理计量学方法，我们将利用中国仓鼠卵巢细胞表达的PAFR来研究萜三酮对克隆的PAFR的影响。将在体外和动物模型中检验萜三酮对长时程增强的影响。这些研究可能为中枢神经系统中需要合成新的银杏内酯和白果内酯配体的萜三酮提供新的靶点。

DESCRIPTION (provided by applicant): This proposal is focused on the mode of action of the ginkgolides and bilobalide (terpenoid trilactones) from the tree Ginkgo biloba. The crude extract of G. biloba, a complex mixture composed of many different compounds, have shown effects on the diseased as well as healthy state of the mammalian brain. Clinical studies, animal studies, and various in vitro studies of the extracts have demonstrated beneficial effects against various neurodegenerative diseases, particularly Alzheimer's disease, as well as memory enhancing effects in the normal brain. However, very little is known about effects of individual constituents, especially at the molecular structural level. In this proposal, we will focus on the most unique constituents of the Ginkgo biloba extract, the ginkgolides and bilobalide, but not on the action of the crude extract which clearly involves synergistic effects, e.g., between the flavonoids (a major component) and the terpenoid trilactones. Some ginkgolides are antagonists of the platelet-activating factor receptor (PAFR), and appear to have antioxidant and neuroprotective properties. We have also found that ginkgolide B is a glycine receptor antagonist, while bilobalide is a potent GABAA receptor antagonist. Our goal is to determine the neuromodulatory effects of terpene trilactones on the mammalian central nervous system, using bioorganic and spectroscopic methods, including those under development in our laboratory on a molecular level. The specific topics to be studied include synthesis of radiotracers for positron emission tomography (PET) and ex vivo autoradiography studies, design and preparation of novel photolabile and fluorescent terpene trilactones analogs to be used to elucidate the interactions of terpene trilactones and PAFR. During these studies we will develop and apply novel methodologies such as ultra-microscale photolabeling and sequencing using unconventional mass spectrometric and circular dichroic techniques, as well as "membrane scissors". Using radioligand binding and microphysiometry, we will initiate studies on the effects of terpene trilactones on the cloned PAFR, using PAFR expressed in Chinese hamster ovary cells. The effects of terpene trilactones on long-term potentiation will be examined in vitro as well as in animal models. These studies can potentially provide new targets for terpene trilactones in the central nervous system that require the synthesis of new ginkgolide and bilobalide ligands.