Design,Synthesis And Evaluation Of Rivastigmine Derivatives As Multifunctional Agents For The Treatment Of Alzheimer’s Disease

Alzheimer’s disease is a neurodegenerative disease that occurs in people over the age of 65.Its etiology is complex,and its pathological mechanism has not been fully elucidated,such as memory impairment,cognitive impairment,behavioral disorder and so on.At present,the drugs on the market can only relieve the disease to a certain extent,but can not reverse the development of AD.Therefore,the research and development of new AD therapeutic drugs is extremely urgent.In view of the complex pathogenesis of AD,a single target drug can not effectively stop the progress of the disease.Multi-target drugs targeting the pathological mechanism of AD has become a new direction of AD therapeutic drugs development.Naringin is a natural flavonoid with multiple pharmacological activities such as antioxidation and neuroprotection,but its low bioavailability limits its application in AD.Salicylic acid is a non-steroidal anti-inflammatory drug found in fruits and vegetables with weak anticholinesterase activity(IC₅₀=346.0μM).Carbamate is a cholinesterase inhibitor approved by the US Food and Drug Administration for the treatment of mild to moderate AD.Carbamate fragment is the key pharmacophore for its inhibition of cholinesterase.In this paper,based on the multi-target design strategy,two kinds of derivatives were designed and synthesized:naringin-O-carbamate derivatives and salicylic acid derivatives.A total of 44 compounds were synthesized.The chemical structures of all compounds were confirmed by ¹H NMR and HRMS,and some of them were characterized by ¹³C NMR.A series of naringin-O-carbamate multifunctional AD drugs were reasonably designed and synthesized.The experimental data in vitro show that compounds TM-3 and TM-14have strong antioxidant activity,Their ORAC values are 1.0 eq and 0.2 eq;TM-3 and TM-14 are reversible hu ACh E inhibitors with IC₅₀values of 9.7μM and 10.6μM,respectively.In addition,TM-3 and TM-14 can inhibit self-induced Aβ_1-42aggregation with inhibition rates of 60.9%and 42.1%,respectively.At the same time,both TM-3 and TM-14can activate UPS degradation pathway in HT22 cells and eliminate AD-related aggregation proteins（tau protein and APP protein）.More importantly,both TM-3 and TM-14 can pass through BBB in vitro.The metal chelation test showed that the compound TM-3 was a selective metal chelating agent,which could inhibit and depolymerize Aβ_1-42aggregation induced by Cu²⁺,and its inhibition rate and depolymerization rate were 66.5%and 54.4%,respectively.At the same time,compound TM-3 also has good neuroprotective and anti-inflammatory effects,and shows a wide range of safety on LO2 cells,and has obvious hepatoprotective effect.Through the ADME prediction of TM-3,it shows good drug-like characteristics.Therefore,compound TM-3 is a potential multi-target anti-AD lead compound.By introducing secondary amine fragment into salicylic acid skeleton,a series of salicylic acid derivatives 3a-3t were designed.The bioactivity results in vitro showed that compound 3a was a selective eq Bu Ch E inhibitor(IC₅₀=0.29μM,SI=26.9),compound 3k was a selective ee ACh E inhibitor(IC₅₀=0.77μM),and compound 3p was a selective eq Bu Ch E inhibitor(IC₅₀=0.82μM,SI=37.3).Compounds 3a,3k and 3p also showed good antioxidant activity,anti-inflammatory properties and selective metal complexing agents,which had obvious neuroprotective effects on PC12 cell injury induced by H₂O₂/Aβ_25-35,and had good ADME properties.We selected 3k and 3p as intermediates,introduced the pharmacophore of capalatine,and synthesized a series of salicylic acid-Donepezil-carbalatine heterozygous 5a-5h after further structural optimization.The results of bioactivity in vitro showed that compound 5a was a reversible selective eq BCh E(IC₅₀=0.53μM)inhibitor and had potential anti-inflammatory effects by inhibiting the production of IL-6,IL-1βand NO.In addition,compound 5a had obvious neuroprotective effect on PC12 cell injury induced by Aβ_25-35,and 5a showed good stability in artificial gastrointestinal juice,liver microsomes and plasma in vitro.5a can also improve the memory impairment caused by scopolamine.Therefore,compound 5a is a potential multi-target anti-AD candidate.This study provides an important clue and theoretical basis for the study of multi-target anti-AD drugs.