The Total Synthesis of Zetekitoxin AB

 描述（由申请人提供）：本研究项目包括非常有效的胍类毒药zetekitoxin AB（ZTX）的全合成。ZTX具有以皮摩尔活性阻断电压门控钠通道（NaV）的卓越能力。然而，与相关胍类毒物相比，其活性增加的结构特征仍然未知。ZTX的合成工作将基于先前在赞助实验室合成相关胍毒素gonyautoxin（GTX）中获得的合成中间体。该路线是突出的铑催化氧化环化，以获得ZTX的双胍核心。将探索和开发相应的合成方法，以获得ZTX的大环内酰胺和N-羟基氨基甲酸酯功能。ZTX的灵活合成将允许ZTX类似物的集中检查，可以提供对与钠通道的特定相互作用的深入了解。将使用全细胞电压钳技术对所有钠通道亚型（NaV 1.1 - 9和NaX）进行电生理学试验，因为迄今为止仅对三种亚型进行了ZTX试验。这将提供一种信息丰富的方法来揭示对任何单个通道亚型的特异性。具有皮摩尔活性的特异性亚型抑制剂将是研究损伤神经元中特异性通道亚型分布的极其有价值的工具。蛋白质诱变将 也可用于探测与特定氨基酸残基的相互作用，这些氨基酸残基被假设为对小分子结合至关重要。该项目的总体目标是完成ZTX的全合成，并增加对NaV通道与ZTX结合效力的理解。从这项研究中获得的知识可能会导致新的简化小分子，有望治疗炎症和神经性疼痛。

 DESCRIPTION (provided by applicant): This research project encompasses the total synthesis of the remarkably potent guanidinium poison, zetekitoxin AB (ZTX). ZTX has an exceptional ability to block volatage-gated sodium channels (NaV) with picomolar activity. However, the structural features responsible for its increased activity compared to related guanidinium poisons remains unknown. Synthetic efforts toward ZTX will be based on previously synthesized intermediates accessed in the sponsoring lab's synthesis of the related guanidinium toxin, gonyautoxin (GTX). The route is highlighted by a rhodium-catalyzed oxidative cyclization to access ZTX's bis-guanidinium core. Synthetic methodology will be explored and developed accordingly to access ZTX's macroclactam and N-hydroxycarbamate functionalities. A flexible synthesis of ZTX would allow a focused examination of ZTX analogues that could provide insight into specific interactions with sodium channels. Electrophysiology assays will be performed using whole-cell voltage-clamp techniques against all sodium channel isoforms (NaV1.1-9 and NaX), as ZTX has only been tested against three isoforms to date. This will provide an information rich approach to reveal specificity towards any individual channel isoform. A specific isoform inhibitor with picomolar activity would be an extremely valuable tool to study the distribution of specific channel isoforms in injured neurons. Protein mutagenesis will also be used to probe proposed interactions with specific amino acid residues hypothesized to be crucial for small molecule binding. This project's overall goal is to complete the total synthesis of ZTX and increase understanding of NaV channels with respect to ZTX's binding efficacy. The knowledge accrued from this study could lead to new simplified small molecules that hold promise for treating inflammation and neuropathic pain.