Screening Natural Phenolic Compounds for Blood-Brain Barrier Permeability, Alongside GSK-3β, CK-1δ, and AChE Inhibition, for the Treatment of Alzheimer's Disease.

Alzheimer's Disease (AD) is a neurological disorder characterized by progressive cognitive impairment and memory loss. In vitro artificial membrane permeability assays targeting the blood-brain barrier (BBB), such as the parallel artificial membrane permeability assay (PAMPA), are useful for pre-evaluating the BBB penetration of molecules during the early stages of drug development. Inhibitors of glycogen synthase kinase-3β (GSK-3β), casein kinase-1δ (CK-1δ), and acetylcholinesterase (AChE) exhibit neuroprotective effects, indicating a potential therapeutic approach for AD. This study aimed to assess the ability of 23 phenolic compounds derived from natural sources to penetrate the central nervous system (CNS) and examine their potential neuroprotective effects. Following the prediction of BBB penetration of the compounds by PAMPA, neuroprotective effects of CNS+ compounds were evaluated through in vitro inhibition of GSK-3β, CK-1δ, and AChE. Based on the data obtained, five flavonoids (hispidulin, nepetin, platanoside, apigenin, and kaempferol) and two furanocoumarins (isopimpinellin and bergapten) were predicted to penetrate the CNS. Apigenin (API) and kaempferol (KEM) exhibited the most potent dual inhibitory activity against CK-1δ and GSK-3β. Furthermore, API and KEM did not exhibit cytotoxic effects in SH-SY5Y cells. Molecular modeling studies, including molecular docking, molecular dynamics simulations, and dynophore analysis, were performed to understand the binding mechanism of these most potent compounds to their target enzymes. Overall, the current study offers a rational approach to designing new molecules inspired by natural compounds to treat Alzheimer's Disease.