Role of Polyphenols in Alleviating Alzheimer’s Disease: A Review

Abstract

Alzheimer’s Disease (AD) is a successive neurodegenerative disorder in the aged population. Many chemicals and phytochemicals are used to treat AD. Polyphenols which occur widely in various fruits, vegetables, beverages, and some other plant sources are gaining importance in AD treatment. Polyphenols comprise various subcategories, such as phenolic acids, lignans, tannins, stilbenes, hydroxybenzoic acid, hydroxycinnamic acid, and flavonoids. These compounds, as sole entities or in combination, can be used for treating AD because they have an abundance of antioxidants that are reported to be effective in free radical scavenging, metal ion chelating, and anti-inflammatory activities. Polyphenols of various plant origins have been studied, and these have been supported by in vitro assays and in vivo studies in rodents. These molecules protect neurons against oxidative stress and deposition of amyloid-β (Aβ) and tau proteins which play a vital role in the pathogenesis of AD. Consumption of wine and other foods rich in polyphenols has a beneficial effect on the neuronal signaling pathways, playing a vital role in shielding neuronal cells from neurodegeneration. Their ability to reduce free radicals and chelate metals is of great advantage. In this review, we highlight the various polyphenols that inhibit neuronal damage and progression of AD while also providing a cure. Some of the polyphenols covered are hesperidin, resveratrol, curcumin, catechin, kaempferol, and quercetin. The mechanisms of the actions of three polyphenols are also elaborated.

Rab11a Controls Cell Shape via C9orf72 Protein: Possible Relationships to Frontotemporal Dementia/Amyotrophic Lateral Sclerosis (FTDALS) Type 1

“…Similar results were obtained in primary cortical neurons. Their decreased morphological changes by Rab11a knockdown are recovered by treatment with hesperetin, a flavonoid with neuronal-protective effects [23][24][25][26]. These effects are supported by the results of phosphorylation states of mitogen-activated protein kinase/extracellular signal-regulated protein kinase (MAPK/ERK) [27][28][29].…”

“…Hesperetin, a citrus flavonoid, has demonstrated neuroprotective effects in neurological diseases such as Parkinsonism, including Parkinson's disease [23][24][25][26]. Its impact extends to dementia, including Alzheimer's disease [23][24][25][26], in indicating neuroprotective properties.…”

“…Hesperetin, a citrus flavonoid, has demonstrated neuroprotective effects in neurological diseases such as Parkinsonism, including Parkinson's disease [23][24][25][26]. Its impact extends to dementia, including Alzheimer's disease [23][24][25][26], in indicating neuroprotective properties. Given these observations, it prompts consideration that hesperetin could potentially restore cellular phenotypes knocked down by siRNA for Rab11a as the major C9orf72 effector.…”

“…Given these observations, it prompts consideration that hesperetin could potentially restore cellular phenotypes knocked down by siRNA for Rab11a as the major C9orf72 effector. In addition, hesperetin has a wide range of protective effects on CNS diseases beyond Alzheimer's and Parkinson's diseases [23][24][25][26]. Therefore, to clarify whether hesperetin has a positive effect on neuronal morphological differentiation, we examined its effects in a time-and concentration-dependent manner.…”

Network pharmacology study on fermented soybeans for the prevention of Alzheimer's disease in older individuals

“…As antioxidants, polyphenols have significant effects in scavenging free radicals, chelating metal ions, and exerting anti‐inflammatory activities. These molecules play a crucial role in AD by protecting neurons from oxidative stress and deposition of amyloid‐beta (Aβ) and tau proteins (Raja et al, 2023; Rezaee et al, 2021; Uddin et al, 2021).…”