Synthesis of derivatives of cleistopholine and their anti-acetylcholinesterase and anti-β-amyloid aggregation activity

Impact of Donepezil Supplementation on Alzheimer's Disease-like Pathology and Gut Microbiome in APP/PS1 Mice

Based on published information, the occurrence and development of Alzheimer's disease (AD) are potentially related to gut microbiota changes. Donepezil hydrochloride (DH), which enhances cholinergic activity by blocking acetylcholinesterase (AChE), is one of the first-line drugs for AD treatment approved by the Food and Drug Administration (FDA) of the USA. However, the potential link between the effects of DH on the pathophysiological processes of AD and the gut microbiota remains unclear. In this study, pathological changes in the brain and colon, the activities of superoxide dismutase (SOD) and AChE, and changes in intestinal flora were observed. The results showed that Aβ deposition in the prefrontal cortex and hippocampus of AD mice was significantly decreased, while colonic inflammation was significantly alleviated by DH treatment. Concomitantly, SOD activity was significantly improved, while AChE was significantly reduced after DH administration. In addition, the gut microbiota community composition of AD mice was significantly altered after DH treatment. The relative abundance of Akkermansia in the AD group was 54.8% higher than that in the N group. The relative abundance of Akkermansia was increased by 18.3% and 53.8% in the AD_G group and the N_G group, respectively. Interestingly, Akkermansia showed a potential predictive value and might be a biomarker for AD. Molecular docking revealed the binding mode and major forces between DH and membrane proteins of Akkermansia. The overall results suggest a novel therapeutic mechanism for treating AD and highlight the critical role of gut microbiota in AD pathology.

Synthesis, biological evaluation and molecular modeling of benzofuran piperidine derivatives as Aβ antiaggregant

A series of benzofuran piperidine derivatives were designed, synthesized and evaluated as multifunctional Aβ antiaggregant to treat Alzheimer's disease (AD). In vitro results revealed that all of them are very good Aβ antiaggregants and some of the compounds are potent acetylcholinesterase (AChE) inhibitors with moderate antioxidant property. Selected compounds were also tested for neuroprotection activity, LDH release, ATP production and inhibitory activity to prevent Aβ peptides binding to the cell membrane. The different modifications introduced in the structure of our lead compound 3 (hAChE IC₅₀ = 61 μM and self induced Aβ _25-35 aggregation 45.45%), to increase its activity toward AD related targets. The most interesting multifunctional Aβ antiaggregants were compounds 3a, 3h and 3i, highlighting 3h as potent Aβ antiaggregant and good antiacetylholinesterase inhibitor (self induced Aβ _25-35 aggregation 57.71% and hAChE IC₅₀ = 21 μM), with good neuroprotective and antioxidant activity. In addition, these three most promising compounds prevent intracellular reactive oxygen species (ROS) formation and cell apoptosis induced by Aβ_25-35 peptides in SH-SY5Y cells. Molecular docking studies were also accomplished to understand the binding interaction of these compounds on Aβ monomer, Aβ fibril and AChE. Based on all data, compounds 3a, 3h and 3i were concluded as potent multifunctional Aβ antiaggregant, useful candidate for the treatment of AD.

Synthesis and biological evaluation of novel 8- substituted sampangine derivatives as potent inhibitor of Zn2+-Aβ complex mediated toxicity, oxidative stress and inflammation

A series of 8-substituted sampangine derivatives have been designed, synthesized and tested for their ability to inhibit cholinesterase and penetrate the blood-brain barrier. Their chelating ability toward Zn²⁺ and other biologically relevant metal ions was also demonstrated by isothermal titration calorimetry. The new derivatives exhibited high acetylcholinesterase inhibitory activity, high blood-brain barrier penetration ability and high chelating selectivity for Zn²⁺. Moreover, compound 10 with the strongest binding affinity to Zn²⁺ was selected for further research. Western blotting analysis, transmission electron microscopy, DCFH-DA assay and paralysis experiment indicated that compound 10 suppressed the formation of Zn²⁺-Aβ complexes, alleviated the Zn²⁺ induced neurotoxicity and inhibited the production of ROS catalyzed by Zn²⁺ in Aβ42 transgenic C. elegans. Furthermore, compound 10 also inhibited the expressions of pro-inflammatory cytokines, such as NO, TNF-α, IL-6 and IL-1β, induced by Zn²⁺ + Aβ_1-42 in BV2 microglial cells. In general, this work provided new insights into the design and development of potent metal-chelating agents for Alzheimer's disease treatment.

Novel sampangine derivatives as potent inhibitors of Cu2+-mediated amyloid-β protein aggregation, oxidative stress and inflammation

A series of 11-substituted sampangine derivatives have been designed, synthesized, and tested for their ability to inhibit cholinesterase. Their chelating ability and selectivity for Cu²⁺ over other biologically relevant metal ions were demonstrated by isothermal titration calorimetry. Their blood-brain barrier permeability was also tested by parallel artificial membrane permeation assay. Among the synthesized derivatives, compound 11 with the strong anti-acetylcholinesterase activity, high blood-brain barrier penetration ability and high binding affinity to Cu²⁺ was selected for further research. Western blotting analysis, transmission electron microscopy, DCFH-DA assay and paralysis experiment indicated that compound 11 suppressed the formation of Cu²⁺-Aβ complexes, alleviated the Cu²⁺ induced neurotoxicity and inhibited the production of ROS catalyzed by Cu²⁺ in Aβ42 transgenic C. elegans. Moreover, compound 11 also inhibited the expressions of proinflammatory cytokines, such as NO, TNF-α, IL-6 and IL-1β, induced by Cu²⁺ + Aβ_1-42 in BV2 microglial cells. In general, this work provided new insights into the design and development of potent metal-chelating agents for AD treatment.

The Antiviral Drug Tilorone Is a Potent and Selective Inhibitor of Acetylcholinesterase

Acetylcholinesterase (AChE) is an important drug target in neurological disorders like Alzheimer's disease, Lewy body dementia, and Parkinson's disease dementia as well as for other conditions like myasthenia gravis and anticholinergic poisoning. In this study, we have used a combination of high-throughput screening, machine learning, and docking to identify new inhibitors of this enzyme. Bayesian machine learning models were generated with literature data from ChEMBL for eel and human AChE inhibitors as well as butyrylcholinesterase inhibitors (BuChE) and compared with other machine learning methods. High-throughput screens for the eel AChE inhibitor model identified several molecules including tilorone, an antiviral drug that is well-established outside of the United States, as a newly identified nanomolar AChE inhibitor. We have described how tilorone inhibits both eel and human AChE with IC₅₀'s of 14.4 nM and 64.4 nM, respectively, but does not inhibit the closely related BuChE IC₅₀ > 50 μM. We have docked tilorone into the human AChE crystal structure and shown that this selectivity is likely due to the reliance on a specific interaction with a hydrophobic residue in the peripheral anionic site of AChE that is absent in BuChE. We also conducted a pharmacological safety profile (SafetyScreen44) and kinase selectivity screen (SelectScreen) that showed tilorone (1 μM) only inhibited AChE out of 44 toxicology target proteins evaluated and did not appreciably inhibit any of the 485 kinases tested. This study suggests there may be a potential role for repurposing tilorone or its derivatives in conditions that benefit from AChE inhibition.

The interactions of an Aβ protofibril with a cholesterol-enriched membrane and involvement of neuroprotective carbazolium-based substances

Recent studies have shown that the aggregation of the amyloid-beta peptide (Aβ) in the brain cell membrane is responsible for the emergence of Alzheimer's disease (AD); the exploration of effective factors involved in the extension of the aggregation process and alternatively the examination of an effective inhibitor via theoretical and experimental tools are among the main research topics in the field of AD treatment. Therefore, in this study, we used all-atom molecular dynamics (MD) simulations to clarify the impact of cell membrane cholesterol on the interaction of Aβ with 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) as a membrane model. Moreover, the effect of the P7C3-S243 molecule on the abovementioned process was investigated. The simulation results disclosed the neuroprotective property of the P7C3-S243 molecule. The MD simulation results indicate that the interaction of cholesterol molecules with the Aβ oligomer is negligible and cannot enhance membrane rupture. However, strong hydrogen bonding between the POPC molecules and the oligomers led to membrane perturbation. According to our modellings, the P7C3-S243 molecular layer can protect the cell membrane by inhibiting the direct interaction between the bilayer and Aβ. In addition, free-energy calculations were conducted to determine the possible penetration of Aβ fibrils into the cholesterol-enriched membrane.