Cholinesterase Inhibitors from Plants: Possible Treatment Strategy for Neurological Disorders – A Review

Dementia is a chronic progressive mental disorder, which adversely affects memory, thinking, comprehension, calculation and language. Some of the most common dementias are Alzheimer’s disease, Parkinsonism, Dementia with Lewy Bodies and Myasthenia gravis. All of these disorders are related to abnormalities in the central cholinergic system, which shows a decline in acetylcholine (ACh) level due to substantial reduction in the activity of the enzyme choline acetyl transferase. A variety of strategies have been envisaged to implement the replacement of ACh, of which acetyl cholinesterase (AChE) inhibition has shown consistent positive results. Cholinesterase inhibitors act on the enzymes that hydrolyze ACh, following synaptic release. Currently several cholinesterase inhibitors such as tacrine, rivastigmine, donepezil and galanthamine have been used as first line pharmacotheraphy for Alzheimer’s disease. However these drugs have severe side effects like hepatotoxicity and gastrointestinal disorder, hence there is still a great interest in finding better cholinesterase inhibitors from natural sources. Natural products are significant sources of synthetic and traditional herbal medicines. A potential source of AChE inhibitors is certainly provided by the abundance of plants in nature. Huperzine, bacosides, hyperforin, desoxy-peganine and Ginko biloba (plant extract) are some of the natural drugs used in the treatment neurological disorders. This article aims to provide a comprehensive literature survey of plants that have been tested for AChE inhibitory activity. Numerous phytoconstituents and promising plant species as AChE inhibitors are being reported in this communication. _____________________________________________________________________________________________________________