Cholinesterase Inhibitory Potential of Quercetin towards Alzheimer’s Disease - A Promising Natural Molecule or Fashion of the Day? - A Narrowed Review

Abstract

: Natural substances are known to have strong protective effects against neurodegenerative diseases. Among them, phenolic compounds, especially flavonoids, come to the fore with their neuroprotective effects. Since quercetin, which is found in many medicinal plants and foods, is also taken through diet, its physiological effects on humans are imperative. Many studies have been published up to date on the neuroprotective properties of quercetin, a flavanol derivative. However, there is no review published so far summarizing the effect of quercetin on the cholinesterase (ChE) enzymes related to the cholinergic hypothesis, which is one of the pathological mechanisms of Alzheimer's disease (AD). However, ChE inhibitors regardless of natural or synthetic play a vital role in the treatment of AD. Although the number of studies on the ChE inhibitory effect of quercetin is limited, it deserves to be discussed in a review article. With this sensitivity, the neuroprotective effect of quercetin against AD through ChE inhibition was scrutinized in the current review study. In addition, studies on the bioavailability of quercetin and its capacity to cross the blood-brain barrier and how this capacity and bioavailability can be increased were given. Generally, studies containing data published in recent years were obtained from search engines such as PubMed, Scopus, and Medline and included herein. Consequently, quercetin should not be considered as a fashionable natural compound and should be identified as a promising compound, especially with increased bioavailability, for the treatment of AD.

Network pharmacology and experiment indicated that medicinal food homologous components play important roles in insomnia

“…We also screened the 10th protein, which is related to Parkinson's syndrome insomnia (PDB code: 1Y7V; Premkumar et al, 2005). Through a literature review, we found that reverse docking with the top nine proteins could directly or indirectly cause insomnia (Duan et al, 2021;Long et al, 2020;Miglis et al, 2021;Orhan, 2021;Rocha-Brito et al, 2022;Romo-Nava et al, 2022; Premkumar et al, 2005) can achieve the effect of treating insomnia.…”

“…We also screened the 10th protein, which is related to Parkinson's syndrome insomnia (PDB code: 1Y7V; Premkumar et al., 2005). Through a literature review, we found that reverse docking with the top nine proteins could directly or indirectly cause insomnia (Duan et al., 2021; Long et al., 2020; Miglis et al., 2021; Orhan, 2021; Rocha‐Brito et al., 2022; Romo‐Nava et al., 2022; Su et al., 2021; Wang et al., 2022; Zhai et al., 2021), and relevant cell experiments or animal experiments have shown that quercetin has an impact on these nine proteins (Ceresa & Peterson, 2014; Cianci et al., 2015; Cuevas et al., 2011; Khodarahmi et al., 2019; Pakdel, 2018; Vieira & Saraiva, 2014). Insomnia is the most immediate symptom experienced by patients with Parkinson's syndrome.…”

UHPLC‐ESI‐QTOF‐MS metabolite profiles of different extracts from Pelargonium endlicherianum parts and their biological properties based on network pharmacological approaches

“…[80,81] In addition, flavonoids such as quercetin, vitexin, or kaempferol showed significant inhibitory effects on cholinesterases. [82][83][84]…”

Polyherbal and Multimodal Treatments: Kaempferol- and Quercetin-Rich Herbs Alleviate Symptoms of Alzheimer’s Disease

“…While its distribution was evidenced in the plasma, liver, heart, spleen, kidneys, and lungs, quercetin levels were non-detectable in the rat brain [326,327]. Hence, it has around 65% BBB permeability [321,328] and is absorbed in the stomach with 24-53% bioavailability [329]. The P-glycoprotein transporter, which is a BBB efflux transporter, has a high affinity for free, unaltered quercetin and greatly reduces its bioavailability by pumping quercetin away from the brain [51,330].…”