Anticholinesterase Inhibitory Activity of Essential Oil and Extracts From Aerial Parts of Melilotus Officinalis

Background & Aims: Medicinal plants serve as a valuable resource for novel approaches to alleviating dementia symptoms.In Persian medicine manuscripts, Melilotus officinalis (sweet clover) was proposed as a treatment for dementia-related symptoms.This study aimed to evaluate the cholinesterase inhibitory activity of sweet clover extracts and essential oil using Ellman's method. Materials & Methods:The essential oil from the aerial parts of sweet clover was obtained via hydrodistillation.Phytochemical composition of the volatile oil was analyzed by GC-MS.Additionally, the plant material was extracted using two solvent systems: (1) petroleum ether, ethyl acetate, and methanol; and (2) n-hexane, dichloromethane, and ethanol.The extracts were dehydrated via ovendrying and freeze-drying.Acetylcholinesterase inhibitory activity of the volatile oil and extracts was assessed using Ellman's test.A preliminary phytochemical analysis of the ethanolic extract was performed by TLC.Results: GC-MS analysis of the volatile oil identified 45.67% of its phytoconstituents, comprising 18 compounds, including hexyl butyrate, phytol, octyl butyrate, and hexahydrofarnesyl acetone.Ellman's test revealed that the volatile oil exhibited no inhibitory activity, whereas the freeze-dried ethanolic extract (200 µg/mL) showed 70.9% inhibition.The freeze-dried extract demonstrated significantly higher inhibitory activity than the oven-dried extract.TLC analysis of the ethanolic extract confirmed the presence of phenolic compounds and coumarins, which are likely responsible for its bioactivity. Conclusion:The freeze-dried ethanolic extract exhibited the strongest acetylcholinesterase inhibitory activity, suggesting that freeze-drying is the preferred dehydration method for sweet clover extracts.Phenolic compounds and coumarins are probable contributors to this inhibitory effect.