Pharmaceutical Studies Aiming at Nerve Cell Degeneration Repairing and Protecting Agent

本研究项目旨在从新型神经营养天然产物中开发神经细胞变性修复和/或保护剂。取得了以下结果。(1)两种类型的无血清原代神经元培养已经建立。利用培养的神经元筛选天然产物，发现9种新的促进神经突起生长的活性物质和6种新的神经保护物质，其中1种对β-淀粉样蛋白诱导的神经元死亡具有保护作用。(2)通过钯催化的反应和/或HRP催化的氧化偶联合成神经营养物质和厚朴酚、乳香烯A和B以及美洲醇A和异美洲醇A。另一方面，通过分子内Stille-Kelly反应成功合成了plagiochin A。目前，我们的工作主要是基于钯催化的Stille-Heck反应合成merrilactone A。(3)通过使用几种抑制剂对和厚朴酚诱导的神经突起生长促进活性进行了药理学研究。结果表明，RTK和MAPK信号通路参与了和诺明介导的神经突起生长。此外，和厚朴的Fluo 3成像分析显示，它可以通过PLC介导的途径增加细胞质游离Ca^2+。厚朴酚能剂量依赖性地阻止加速衰老小鼠海马CA 1区密度的降低。

This research project has been performed toward development of nerve cell degeneration repairing and/or protecting agent from novel neurotrophic natural products. The following results have been obtained.(1) Two types of serum-free primary neuronal cultures have been established. Screening natural products by using these cultured neurons nine new neurite outgrowth promoting active substances and six new neuroprotective substances have been found. One of them, in particular, could protect β-amyloid-induced death of neurons.(2) Neurotrophic substance, honokiol, mastigophorenes A and B, and americanol A and isoamericanol A were synthesized by palladium-catalyzed reactions and/or HRP-catalyzed oxidative coupling. On the other hand, synthesis of plagiochin A was succeeded by intramolecular Stille-Kelly reaction. Now, our effort has directed to the synthesis of merrilactone A based on palladium-catalyzed sequential Stille-Heck reaction.(3) Pharmacological studies on honokiol-induced neurite outgrowth promoting activity were carried out by using several inhibitors. As results, RTK and MAPK signal pathway was indicated to be involved in neurite outgrowth mediated by honokiol. Additionally, Fluo 3 imaging analysis of honokiol showed that it can increase cytoplasmic free Ca^<2+> through a PLC-mediated pathway. It is worthy of note that magnolol, a analog of honokiol, could dose-dependently prevent the decrease of density of the CA1 in the hippocampus of senescence-accelerated mice (SAM).