Objective To screen acetylcholinesterase (AChE) inhibitors from the specific medicinal herbs Peganum multisectum by affinity ultra-filtration-liquid chromatography-mass spectrometry (AUF-LC-MS), and to explore their inhibition mechanisms. Methods The AChE inhibitory activities of various polar fractions of P. multisectum were evaluated by Ellman’s test, and the active components were precisely screened by AUF-LC-MS. The action mechanisms of the active components on AChE were investigated by enzyme inhibition kinetics, molecular docking and molecular dynamics simulations. Results A total of seven active components, including one flavonoid and six alkaloids, were identified from the dichloromethane and n-butanol fractions. Enzyme inhibition kinetics suggested that these components belonged to three inhibition types: reversible competitive inhibition (linarin), non-competitive (vasicine, vasicinone and harmol), and reversible mixed inhibition (deoxyvasicine, deoxyvasicinone and harmaline). Molecular docking results revealed that all compounds exhibited good affinities to AChE. And the binding sites and interaction forces of these inhibitors with AChE differed. Molecular dynamics simulation indicated that the system had reached a stable state, and the inhibitors had strong and stable interactions with AChE. Conclusions This study provided a scientific basis for elucidating the potential of P. multisectum in the prevention and treatment of Alzheimer’s disease and offered a new reference for the discovery of high-efficiency AChE inhibitors.

Alzheimer’s disease  /  acetylcholinesterase inhibitors  /  Peganum multisectum (Maxim.) Bobr.  /  affinity ultra-filtration-liquid chromatography-mass spectrometry  /  inhibition mechanism  /  linarin  /  vasicine