Design And Synthesis Of Novel Bifunctional Molecules As Tau-aggregation Inhibitors And Microtubule-stabilizing Agents

Alzheimer (Alzheimer disease, AD) is a degenerative disease of the central nervous system, showed a chronic progressive course. It is also the most common type of senile dementia. This disease is a serious threat to people’s live and health. The latest research shows that in developed countries 13% of people aged over 65 suffer from this disease. It is also the fifth leading cause of death at this age. Concerning the pathology of AD, there are currently three main hypotheses:Amyloid (Aβ) deposition; neurofibrillary tangles (NFTs) and degeneration of cholinergic neurons. Over the past ten years, research for anti-AD drugs mostly based on the Aβ cascade hypothesis. But recently, some of the,Aβ-targeting drugs in clinical Phase III trials ended in failure. Therefore, the important role of "neurofibrillary tangles" in the AD disease has been widely recognized.More and more studies show that tau proteins play a key role in the AD process. Abnormally modified tau, in particular, tau protein levels and phosphorylation of Tau become toxic molecules and lead to the accumulation of PHF, neurofibrillary degeneration and the impact of mitochondrial function. The study of tau-focused targets for treatment of Alzheimer’s disease is still at the early stage. Most of drugs molecules are in the design stage, only a small portion entered clinical phase II trials. On the other hand, tau is a microtubule-associated protein. Hyperphosphorylation of tau protein will result in the polymerization and affect microtubule stability. Thus, microtubule stabilizing agent can compensate the function of the protein tau which is missing, adjust the dynamic stability of microtubules, and restore normal axonal transport function, thereby protecting the nerve cells for the purpose in the treatment of Alzheimer’s diseases. This type of microtubule stabilizing agents used for the treatment of AD has been currently confirmed in animal experiments.Thus, a series of 1-phenyl-2,5-dione derivatives have been synthesized in this thesis, which can inhibit the polymerization of tau protein and stabilize microtubules. These compounds will be probably more effective in the treatment of Alzheimer’s disease. The method used in this thesis is organic synthesis, spectral analysis, test of inhibition of tau protein polymerization and stability of microtubules in vitro. Based on the structure of 1-phenyl-pyrrolidine-2,5-dione, we have designed and synthesized three series of new compounds (nearly 20 compounds, the structure of these compounds are novel and they have not been reported).Tubulin is extracted according to the characteristics of tubulin depolymerization at lower temperatures and polymerization at room temperature (37℃). Using ultra high-speed centrifuge, tubulin is extracted, step by step, and purified. The protein purity was verified by electrophoresis. From the purity analysis, it showed that the protein can be used for the following test.The test results show that the synthesized compounds have the inhibitory activity of tau protein aggregation which is more potent than methylene blue. In the meanwhile, they have also the effect of stabilizing microtubules, which is more effective than paclitaxel as positive control. In particular, the compound 12a2 in the series III can stabilize well microtubules and also effectively inhibit the tau protein aggregated. Such compound could be used as a potential candidate for the anti-Alzheimer’s drugs.