Identifying amine fragments as potential inhibitors of acetylcholinesterase and butyrylcholinesterase through in silico analysis and validation through in vitro enzyme inhibition analysis

Abstract

AbstractBackgroundThe cholinesterases [ChEs; acetylcholinesterase (AChE) and butyrylcholinesterase (BChE)] which are involved in cholinergic neurotransmission are target for drug development against cognitive dysfunction in Alzheimer’s disease. The search for novel ChEs inhibitors with improved biological profiles continues to be of great interest. Currently know inhibitors of ChEs such as galatamine, tacrine, donepezil and rivastigmine are amine‐based compound. Keeping this view, in the present study virtual screening was carried out to identify the potential amine fragment that interacted with the ChEs in in silico. The selected molecules were analyzed by molecular docking and molecular dynamics simulation. The best interacted molecule in in silico was further characterized for its inhibition against AChE and BChE in in vitro.MethodHigh Throughput Virtual Screening (HTVS) of various amine fragments was carried out in Schrödinger suite. Identified top ten molecules were subjected to molecular docking analysis using Induced Fit Docking (IFD) module. Molecular dynamics (MD) simulation of top three scored compounds were carried out to understand the stability of the interaction with ChEs. In silico quantum crystallography studies was done to understand the involvement of functional group in the interaction with ChEs. In vitro inhibition and kinetic analysis of these compounds against ChEs was performed to determine the inhibitory constant and type of inhibition.ResultAmong the amine compounds screened, three compounds 2‐aminoquinoline (2AQ), 2‐aminobenzimidazole (2AB) and 2‐amino‐1‐methylbenzimidazole (2AMB) was identified to interact with ChEs with lowest docking score. Further MD simulation confirmed the stable binding of these compounds in the active site of the ChEs. Topological and electrostatic properties of intermolecular interactions between these compounds with ChEs showed that amine group played important role in interacting with protein structure. These amine compounds inhibited the BChE and different molecular forms of AChE at micromolar concentration. Kinetic analysis revealed the mixed‐type of inhibition.ConclusionAmine fragments screened for interaction with ChEs in in silico. Three compounds (2AQ, 2AB and 2AMB) showed better interaction in molecular docking and molecular dynamics analysis. These compounds showed inhibition against ChEs in in vitro.