Design, Synthesis and Evaluation of 4-Aminopyridine Analogues as Cholinesterase Inhibitors for Management of Alzheimer’s Diseases

Introduction: Alzheimer’s disease (AD) is a slowly progressive devasting neurodegenerative disorder of central nervous system manifested by deterioration of memory, cognitive functions, behaviour change and impairment in performing activities of daily life. Neurochemical studies of patients suffering from AD demonstrate selective loss of cholinergic neurons, low concentration of acetylcholine (Ach) in the selective areas of brain such as cortex and hippocampus. Objective: A series of new semicarbazones of 4-aminopyridine has been designed, synthesized and evaluated for cognition enhancing activities through the inhibition of acetylcholinesterase (AChE) and by passive avoidance model. Material and methods: In the present study, ten new 4-Aminopyridine analogues were synthesized and characterized by analytic methods such as UV, IR, NMR, elemental analysis and for their inhibitory role on Acetylcholinesterase activity by applying the molecular docking studies and performed enzyme kinetics study by Ellman’s spectrophotometric method. The synthesized analogues were then evaluated for antiamnesic and cognition enhancing activities by passive avoidance test. Results: The results illustrated a significant cognition enhancing effect on passive avoidance test with a significant reversal of scopolamine-induced amnesia, which is comparable with standard drug rivastigmine. The in-vitro study of synthesized analogues showed maximum activity of compound-3 and compound-9 compared to standard drug rivastigmine, whereas its enzyme kinetic study revealed a non-competitive inhibition of acetylcholinesterase (AChE) is held responsible to a possible interaction of analogue with the peripheral anionic site (PAS) of AChE and was also confirmed by molecular docking studies. Conclusion: On the basis of present study, we are concluding that hydroxyl substituted Compound 3 and 9 identified as most potent drug which can leads to the discovery and development of new Cognition enhancers in near future.