HPTLC-based Bioassay Screening of Selected Indigenous Plants for Acetylcholinesterase Inhibitory Activity

Introduction:: Alzheimer’s disease (AD) is a neurodegenerative disorder marked by memory loss and cognitive decline, primarily linked to the excessive breakdown of acetylcholine by the enzyme Acetylcholinesterase (AChE), which impairs neurotransmission. Current research is exploring plant-derived compounds that inhibit AChE, offering a potential therapeutic approach for AD. : This study aimed to screen indigenous medicinal plants and their parts for acetylcholinesterase inhibitory activity. Methods: Eleven medicinal plants from the Rajasthan state of India were collected. Twenty-six plant extracts were prepared using methanol. AChE inhibitory activity was assayed using a spectrophotometer and HPTLC bioassay based on Ellman's method. Experiments were conducted in triplicate. Results: TLC bioautographic (qualitative) (with the concentration of methanolic extract being 10mg/ml and inhibition time approximately 15-20 minutes) and spectrophotometric (quantitative) (with the concentration of methanolic extract being 1mg/ml and inhibition time approximately 2-3 minutes) methods revealed that extracts from nine of the eleven plant species exhibited AChE inhibitory activity. Specifically, the fruit extract of Cucumis callosus Cogn exhibited maximum activity (73.72 ± 3.93%), and the flower extract of Trifolium alexandrinum L. demonstrated minimum (19.78 ± 3.09%) acetylcholinesterase inhibitory activity. Discussion: AChE inhibitors derived from plant extracts have gained significant attention due to their potential in managing Alzheimer’s disease. Natural AChE inhibitors are often associated with fewer side effects compared to synthetic drugs, making them promising candidates for therapeutic development. Continued exploration of plant-based inhibitors could lead to safer and more effective treatments for cognitive decline. Conclusion: In conclusion, fourteen extracts from nine plant species exhibited notable cholinesterase inhibition, suggesting their potential as candidates for further research.