In vitro therapeutic potential of selected flavonoids, polyphenols and vitamins against Alzheimer’s disease

Alzheimer's disease is a progressive neurodegenerative disease that leads to impaired cognition.One of the important factors for neurodegeneration and memory impairment is depleted levels of acetylcholine, especially in the brain.Compounds that inhibit cholinesterase enzyme, which is involved in the metabolism of acetylcholine, will help in maintaining the optimum levels of acetylcholine to prevent degenerative changes in the neuron, especially in the brain.Natural compounds obtained from the plants possess various pharmacological properties that can be explored for their therapeutic potential in Alzheimer's disease.They target the cholinesterase inhibitory potential, thereby maintaining the optimum levels of acetylcholine.By keeping this in view, the present study was designed to determine the cholinesterase enzyme inhibition of selected flavonoids, polyphenols and vitamins.Four flavonoids, namely quercetin, morin, naringenin and chrysin; four vitamins, thiamine, pyridoxine, beta-carotene and ascorbic acid; and seven polyphenols, namely ellagic acid, tannic acid, cinnamic acid, quinic acid, syringic acid, ferulic acid and shikimic acid were used.The cholinesterase enzyme inhibition was measured as per Ellmans method using neostigmine as positive control in fish brain homogenate.The range of percentile inhibition of tested flavonoids was found to be 42% to 55%.While the percentage of ascorbic acid inhibition is higher among the vitamins screened.In the category of polyphenols, ferulic acid (66%), shikimic acid (66%) and syringic acid (65.58%) showed better cholinesterase enzyme inhibitory activity when compared to other compounds.From the above results, it is concluded that natural compounds like flavonoids, polyphenols and vitamins can be used as alternatives to synthetic cholinesterase inhibitors in Alzheimer's disease to prevent neuronal degeneration.