Design,synthesis And Biological Activity Evaluation Of Coumarin-dithiocarbamate Hybrids Against Alzheimer’s Disease

Alzheimer’s disease（AD）is one of the most disastrous neurodegenerative diseases characterized by memory loss,degradation in language skills and cognitive deficits.According to the statistical report from Alzheimer’s Association,nearly 47million people worldwide are suffering from AD,and the number of patients will exceed 100 millionby 2050.Nowadays,the strategy for development of drugs against AD has shifted from the conventional paradigm of“one drug,one target”to develop multi-target-Directed Ligands（MTDLs）due to the multifactorial etiopathogenesis of AD.Among the reported MTDLs against AD,the dual acetylcholinesterase/monoamine oxidase-B（AChE/MAO-B）target inhibitors have shown excellent therapeutic effects in clinical studies.Thus,development of dual target inhibitors for AChE/MAO-B is one of the most attractive areas.A series of coumarin-dithiocarbamate hybrids were designed and synthesized as AChE/MAO-B dual target inhibitors in this study.The research content mainly includes the following seven parts:PartⅠ:Some important etiopathogenesis of AD were introduced.The current research and development status of anti-AD drugs was also summarized in this part,including AChE inhibitors,MAO-B inhibitors and AChE/MAO-B dual inhibitors.Part Ⅱ:Twenty-eight compounds of coumarin-dithiocarbamate derivatives were designed and synthesized by bioelectron isosteric and conjugated-pharmacophore strategy.The structure and purity of all target compounds were confirmed by ¹H NMR,¹³C NMR,IR,HR-ESI-MS and HPLC.Part Ⅲ:The inhibition activities of designed compounds 7a-n and 8a-n against ChEs and MAOs were determined according to Ellman’s and Amplex Red fluorescence method,respectively.The results showed most compounds exhibited good inhibitory activity on both AChE and MAO-B.Among these compounds,compound 8f showed the most potent inhibition on AChE(eeAChE:IC₅₀=0.0068μM;hAChE:IC₅₀=0.0089μM),which was more potent than that of the reference drug donepezil(eeAChE:IC₅₀=0.041μM;hAChE:IC₅₀=0.021μM).Compound 8g exhibited the potent and well balanced inhibitory activity on both AChE and MAO-B(hAChE:IC₅₀=0.114μM;hMAO-B:0.101μM).In addition,the structure-activity relationships of compounds were analyzed according to experiment results.Part Ⅳ:Compounds 7c,7g,8f-g and 8j-k with strong inhibitory activity on both hAChE and hMAO-B were selected to determine their permeabilities for BBB by the parallel artificial membrane permeation assay of blood-brain barrier（PAMPA-BBB）.The results showed all compounds exhibited good BBB permeability with exception of compound 8f that exhibited an uncertain BBB permeation.Part Ⅴ:Kinetic and molecular modeling study suggested compound 8g was a mixed-type inhibitor,binding simultaneously to CAS,PAS and mid-gorge site of AChE,and it was also a competitive inhibitor,which could occupy the substrate and entrance cavities of MAO-B.Part Ⅵ:The cytotoxicity study in vitro and in in vivo indicated that compound8g showed no toxicity to SH-SY5Y cells and mice within the dose range.Part Ⅶ:The therapeutic effect in vivo of compound 8g was tested using the scopolamine-induced cognitive deficit mouse model.The results showed that compound 8g could obviously improve the memory deficit of mice.