Acetylcholinesterase inhibitory activity of extract and essential oil of aerial parts of Melilotus officinalis

Abstract

Introduction: Alzheimer's is one of the most common neurodegenerative diseases and the most important cause of dementia. Acetylcholinesterase inhibitors have been the most effective drug class in improving the symptoms of this disease. The increasing desire of people to consume natural ingredients has also led our study to this field by citing traditional medicine sources. Melilotus officinalis is a biennial plant with a maximum height of 1 meter native to Iran. In traditional medicine, the flowering branch has been used in inflammatory diseases, insomnia, high blood pressure, anticoagulation, and wound healing. This study aimed to investigate new natural compounds with inhibitory effect on acetylcholinesterase, from the essential oil and extract of this plant were studied.Aim: Acetylcholinesterase inhibitory activity of extracts and essential oil of aerial parts of Melilotus officinalis.Method: The flowering branches of this plant were collected and identified. The essential oil was obtained by Clevenger apparatus and the extracts were acquired by soxhlet extraction. Acetylcholinesterase inhibition of essential oil and extracts was measured by Ellman's method. Acetylthiocholine iodide (ATCI) was used as a substrate, and donepezil was used as a positive control to measure the inhibition of acetylcholinesterase. Molecular modeling studies were performed with AutoDocktools-1.5.6 software to study the interaction mechanism of compounds.Result: In the Ellman test, the highest inhibition was related to freeze-dried ethanolic extract with inhibitory activity of 70.9%, vaccium-dried ethanolic extract with 49.5% inhibition, and freeze-dried methanolic extract with 28.1% inhibition.In docking studies, triterpenoid and flavonoid compounds showed strong interactions in the Enzyme active site.Conclusion: It seems that flavonoid and triterpenoid compounds are among the main effective compounds in the occurrence of cholinesterase inhibitory effect.