Neuromodulatory Effects of Ginkgolides and Bilobalide

性状（由申请方提供）：本提案侧重于银杏树中银杏内酯和白果内酯（萜类三内酯）的作用方式。采用粗提物法提取G.银杏是一种由许多不同化合物组成的复杂混合物，已经显示出对哺乳动物大脑的疾病和健康状态的影响。提取物的临床研究、动物研究和各种体外研究已经证明了对各种神经变性疾病，特别是阿尔茨海默病的有益作用，以及在正常大脑中的记忆增强作用。然而，很少有人知道个别成分的影响，特别是在分子结构水平。在本提案中，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，但不关注粗提物的作用，粗提物明显涉及协同效应，例如，类黄酮（主要成分）和萜类三内酯之间的关系。一些银杏内酯是血小板活化因子受体（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。我们的目标是确定萜烯三内酯对哺乳动物中枢神经系统的神经调节作用，使用生物有机和光谱方法，包括在分子水平上我们实验室正在开发的方法。要研究的具体课题包括合成放射性示踪剂的正电子发射断层扫描（PET）和离体放射自显影研究，设计和制备新的光不稳定和荧光萜烯三内酯类似物，用于阐明萜烯三内酯和PAFR的相互作用。在这些研究中，我们将开发和应用新的方法，如使用非传统的质谱和圆二色性技术，以及“膜剪刀”的超微光标记和测序。使用放射性配体结合和微生理学，我们将开始研究萜烯三内酯对克隆的PAFR的影响，使用在中国仓鼠卵巢细胞中表达的PAFR。萜烯三内酯对长时程增强的影响将在体外以及动物模型中进行检查。这些研究可能为萜类三内酯在中枢神经系统中提供新的靶点，这需要合成新的银杏内酯和白果内酯配体。

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.