An ongoing journey of chalcone analogues as single and multi-target ligands in the field of Alzheimer's disease: A review with structural aspects

Protective effect of flavonoids on oxidative stress injury in Alzheimer's disease

Alzheimer's disease (AD) is the most common neurodegenerative disease, which is mainly caused by the damage of the structure and function of the central nervous system. At present, there are many adverse reactions in market-available drugs, which can't significantly inhibit the occurrence of AD. Therefore, the current focus of research is to find safe and effective therapeutic drugs to improve the clinical treatment of AD. Oxidative stress bridges different mechanism hypotheses of AD and plays a key role in AD. Numerous studies have shown that natural flavonoids have good antioxidant effects. They can directly or indirectly resist -oxidative stress, inhibit Aβ aggregation and Tau protein hyperphosphorylation by activating Nrf2 and other oxidation-antioxidation-related signals, regulating synaptic function-related pathways, promoting mitochondrial autophagy, etc., and play a neuroprotective role in AD. In this review, we summarised the mechanism of flavonoids inhibiting oxidative stress injury in AD in recent years. Moreover, because of the shortcomings of poor biofilm permeability and low bioavailability of flavonoids, the advantages and recent research progress of nano-drug delivery systems such as liposomes and solid lipid nanoparticles were highlighted. We hope this review provides a useful way to explore safe and effective AD treatments.

Synthesis of novel aryl-substituted 2-aminopyridine derivatives by the cascade reaction of 1,1-enediamines with vinamidinium salts to develop novel anti-Alzheimer agents

Alzheimer's disease (AD), a severe neurodegenerative disorder, imposes socioeconomic burdens and necessitates innovative therapeutic strategies. Current therapeutic interventions are limited and underscore the need for novel inhibitors of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), enzymes implicated in the pathogenesis of AD. In this study, we report a novel synthetic strategy for the generation of 2-aminopyridine derivatives via a two-component reaction converging aryl vinamidinium salts with 1,1-enediamines (EDAMs) in a dimethyl sulfoxide (DMSO) solvent system, catalyzed by triethylamine (Et3N). The protocol introduces a rapid, efficient, and scalable synthetic pathway, achieving good to excellent yields while maintaining simplistic workup procedures. Seventeen derivatives were synthesized and subsequently screened for their inhibitory activity against AChE and BChE. The most potent derivative, 3m, exhibited an IC50 value of 34.81 ± 3.71 µM against AChE and 20.66 ± 1.01 µM against BChE compared to positive control donepezil with an IC50 value of 0.079 ± 0.05 µM against AChE and 10.6 ± 2.1 µM against BChE. Also, detailed kinetic studies were undertaken to elucidate their modes of enzymatic inhibition of the most potent compounds against both AChE and BChE. The promising compound was then subjected to molecular docking and dynamics simulations, revealing significant binding affinities and favorable interaction profiles against AChE and BChE. The in silico ADMET assessments further determined the drug-like properties of 3m, suggesting it as a promising candidate for further pre-clinical development.

MAO-B Inhibitor (2E)-3-(4-Bromophenyl)-1-(1H-indol-3-yl) prop-2-en-1-one as a Neuroprotective Agent Against Alzheimer's Disease

Chalcones (trans-1,3-diphenyl-2-propen-1-ones) form simple chemical structures that act as precursors for the biogenesis of flavonoids. These are distributed in plants and have two aromatic or heteroaromatic rings connected by a three-carbon α, β-unsaturated carbonyl group. Considering the importance of chalcones as monoamine oxidase and acetylcholinesterase inhibitors, the study was designed as a comprehensive and systematic analysis to evaluate the pharmacological activities leading to the formation of drug molecules against Alzheimer's disease (AD). Based on our previous research, 11 indolyl chalcones (IC1-IC11) were synthesised and investigated for MAO-B inhibitory activity. The inhibitory potential was evaluated based on binding and reversibility studies using purified enzymes. The active and most promising molecule, (2E)-3-(4-bromophenyl)-1-(1H-indol-3-yl) prop-2-en-1-one (IC9), also found predominant acetylcholinesterase inhibition and hence it was found dual acting in vitro. Based on this, the molecule IC9 was further subjected to cell line studies to further explore its role as a neuroprotective agent against neuronal degeneration, one of the main contributing parameters related to AD.

Dinuclear copper(II) complexes with a bridging bis(chalcone) ligand reveal considerable in vitro cytotoxicity on human cancer cells and enhanced selectivity

A bis(chalcone) molecule (H2L) was synthesized via Aldol's condensation from terephthalaldehyde and 2'-hydroxyacetophenone and it was used as bridging ligand for the preparation of five dinuclear copper(II) complexes of the composition [Cu(NN)(μ-L)Cu(NN)](NO3)2⋅nH2O (n = 0-2) (1-5), where NN stands for a bidentate N-donor ligand such as phen (1,10-phenanthroline, 1), bpy (2,2'-bipyridine, 2), mebpy (5,5'-dimethyl-2,2'-dipyridine, 3), bphen (bathophenanthroline, 4) and nphen (5-nitro-1,10-phenanthroline, 5). The compounds were characterized by different suitable techniques to confirm their purity, composition, and structure. Moreover, the products were evaluated for their in vitro cytotoxicity on a panel of human cancer cell lines: ovarian (A2780), ovarian resistant to cisplatin (A2780R), prostate (PC3), osteosarcoma (HOS), breast (MCF7) and lung (A549), and normal fibroblasts (MRC-5), showing significant cytotoxicity in most cases, with IC50 ≈ 0.35-7.8 μM. Additionally, the time-dependent cytotoxicity and cellular uptake of copper, together with flow cytometric studies concerning cell-cycle arrest, induction of cell death and autophagy and induction of intracellular ROS/superoxide production in A2780 cells, were also performed. The results of biological testing on A2780 cells pointed out a possible mechanism of action characterized by the G2/M cell cycle arrest and induction of apoptosis by triggering the intrinsic signalling pathway associated with the damage of mitochondrial structure and depletion of mitochondrial membrane potential. SYNOPSIS: Dinuclear Cu(II) complexes bearing a bridging bis(chalcone) ligand revealed high in vitro cytotoxicity, initiated A2780 cell arrest at G2/M phase and efficiently triggered intrinsic pathway of apoptosis.

N-methylpiperazinyl and piperdinylalkyl-O-chalcone derivatives as potential polyfunctional agents against Alzheimer's disease: Design, synthesis and biological evaluation

The series of N-methylpiperazinyl and piperdinylalkyl-O-chalcone derivatives as potential polyfuctional agents against Alzheimer's disease that have been designed, synthesized and then evaluated biologically using in vitro assays for the inhibition of acetylcholinesterase (AChE) activity, AGEs, and free radical formation. The majority of synthesized compounds inhibited AChE & AGEs with additional free radical scavenging activities at nanomolar concentrations. Among these, compound 5k was found to have potent AChE inhibitory activity (IC50  = 11.6 nM), superior than the reference compound donepezil (15.68 nM) along with the good anti-AGEs and free radical formation effect. Its potency was justified by docking studies that revealed its dual binding characteristic with both catalytic active site and peripheral anionic site of AChE, simultaneously. Furthermore, the in vivo evaluation of 5k against streptozotocin (STZ)-induced dementia in rats also showed improvement of memory functions (Morris water maze test) in animals. Also, 5k inhibited STZ-inudced brain AChE activity and oxidative stress which further strengthen the observed in vitro effects. The stability of the ligand-protein complex was then analyzed using a simulation-based interaction protocol. The results revealed that these N-methylpiperazinyl and piperdinylalkyl-O-chalcone derivatives could be considered for potential polyfunctional anti-Alzheimer's molecules.

Computational Studies to Understand the Neuroprotective Mechanism of Action Basil Compounds

Neurodegenerative diseases, such as Alzheimer's and Parkinson's, pose a significant global health challenge, emphasizing the need for novel neuroprotective agents. Basil (Ocimum spp.) has been recognized for its therapeutic potential, and numerous studies have reported neuroprotective effects. In this manuscript, we present a computational protocol to extricate the underlying mechanism of action of basil compounds in neuroprotective effects. Molecular docking-based investigation of the chemical interactions between selected bioactive compounds from basil and key neuroprotective targets, including AChE, GSK3β, γ-secretase, and sirtuin2. Our results demonstrate that basil compound myricerone caffeoyl ester possesses a high affinity of -10.01 and -8.85 kcal/mol against GSK3β and γ-secretase, respectively, indicating their potential in modulating various neurobiological processes. Additionally, molecular dynamics simulations were performed to explore the protein-ligand complexes' stability and to analyze the bound basil compounds' dynamic behavior. This comprehensive computational investigation enlightens the putative mechanistic basis for the neuroprotective effects of basil compounds, providing a rationale for their therapeutic use in neurodegenerative disorders after further experimental validation.

Recent Development of Novel Aminoethyl-Substituted Chalcones as Potential Drug Candidates for the Treatment of Alzheimer's Disease

No drug on the market, as a single entity, participates in different pathways involved in the pathology of Alzheimer's disease. The current study is aimed at the exploration of multifunctional chalcone derivatives which can act on multiple targets involved in Alzheimer's disease. A series of novel aminoethyl-substituted chalcones have been developed using in silico approaches (scaffold morphing, molecular docking, and ADME) and reported synthetic methods. The synthesized analogs were characterized and evaluated biologically using different in vitro assays against AChE, AGEs, and radical formation. Among all compounds, compound PS-10 was found to have potent AChE inhibitory activity (IC50 = 15.3 nM), even more than the standard drug (IC50 = 15.68 nM). Further, the in vivo evaluation of PS-10 against STZ-induced dementia in rats showed memory improvement (Morris Water Maze test) in rats. Also, PS-10 inhibited STZ-induced brain AChE activity and oxidative stress, further strengthening the observed in vitro effects. Further, the molecular dynamic simulation studies displayed the stability of the PS-10 and AChE complex. The novel aminoethyl-substituted chalcones might be considered potential multifunctional anti-Alzheimer's molecules.