Background: Using of acetylcholinesterase inhibitors is one of the methods for treatment of Alzheimer disease currently. Plants are rich sources for many bioactive compounds. So searching for new drugs with better properties and fewer side effects from plants is the aim of many studies.

Objective: The purpose of this study was to investigate acetylcholinesterase activity inhibition by methanol extract of the aerial parts of screened plants, Alcea kurdica (Schlecht.) Alef and Astragalus glumaceus Bioss.

Methods: Using a modified version of Ellman’s microplate assay method, acetylcholinesterase inhibitory activity of methanol extracts from various aerial organs (flowers, stems, leaves) of plants Alcea kurdica and Astragalus glumaceus at four different concentrations were investigated. Electric eel acetylcholinesterase was used in this study. Galanthamine, dissolved in methanol, used as a positive control and each experiment was done in triplicate.

Results: The results revealed that the methanol extract from flower organ of Alcea kurdica and leaves of Astragalus glumaceus, at 2 mg/ml concentration, inhibited the enzyme activity with 63.45 and 53.58 inhibition percent respectively. Their IC₅₀ values were 0.114 and 0.216 mg/ml respectively. According to the results enzyme inhibition kinetics analysis, methanol extract from flower organs of Alcea kurdica and leaves of Astragalus glumaceus showed competitive and mixed (competitive – noncompetitive) inhibition, respectively.

Conclusion: These results suggest that the most effective plant’s organ extracts in this study, be worthy of further investigation with the aim of obtaining new acetylcholinesterase inhibitors with pharmacological applications.