Novel neuroprotective pyromeconic acid derivatives with concurrent anti-Aβ deposition, anti-inflammatory, and anti-oxidation properties for treatment of Alzheimer's disease

The compound (E)-2-(3,4-dihydroxystyryl)-3-hydroxy-4H-pyran-4-one alleviates neuroinflammation and cognitive impairment in a mouse model of Alzheimer's disease

JOURNAL/nrgr/04.03/01300535-202511000-00034/figure1/v/2024-12-20T164640Z/r/image-tiff Previous studies have shown that the compound (E)-2-(3,4-dihydroxystyryl)-3-hydroxy-4H-pyran-4-one (D30), a pyromeconic acid derivative, possesses antioxidant and anti-inflammatory properties, inhibits amyloid-β aggregation, and alleviates scopolamine-induced cognitive impairment, similar to the phase III clinical drug resveratrol. In this study, we established a mouse model of Alzheimer's disease via intracerebroventricular injection of fibrillar amyloid-β to investigate the effect of D30 on fibrillar amyloid-β-induced neuropathology. Our results showed that D30 alleviated fibrillar amyloid-β-induced cognitive impairment, promoted fibrillar amyloid-β clearance from the hippocampus and cortex, suppressed oxidative stress, and inhibited activation of microglia and astrocytes. D30 also reversed the fibrillar amyloid-β-induced loss of dendritic spines and synaptic protein expression. Notably, we demonstrated that exogenous fibrillar amyloid-β introduced by intracerebroventricular injection greatly increased galectin-3 expression levels in the brain, and this increase was blocked by D30. Considering the role of D30 in clearing amyloid-β, inhibiting neuroinflammation, protecting synapses, and improving cognition, this study highlights the potential of galectin-3 as a promising treatment target for patients with Alzheimer's disease.

A novel carbamate-based hybrid derivative with anti-neuroinflammatory properties as a selective butyrylcholinesterase inhibitor for Alzheimer's disease therapy

Cholinesterase inhibitors (ChEIs) are widely utilized for the symptomatic management of Alzheimer's disease (AD) by enhancing acetylcholine levels to improve cognitive function. Concurrently, neuroinflammation has emerged as a critical factor in AD progression, necessitating therapies that address this pathology. In this study, we designed and synthesized a novel bifunctional cholinesterase inhibitor, (E)-4-(2-(3-(benzyloxy)-4-oxo-4H-pyran-2-yl) vinyl)-1,2-phenylene bis(ethyl(methyl)carbamate) (D40), which combines potent cholinesterase inhibition with robust anti-neuroinflammatory activity. D40 demonstrated potent inhibition of human butyrylcholinesterase (hBuChE), with an IC₅₀ value of 0.59 ± 0.03 μM, significantly outperforming Rivastigmine (IC₅₀ = 3.70 ± 0.96 μM). Molecular docking and molecular dynamics simulations confirmed a stable and selective binding of D40 to the BuChE active site, underpinning its inhibitory profile. Additionally, D40 exhibited strong anti-inflammatory effects, with an IC₅₀ value of 4.55 ± 0.78 μM for suppressing nitric oxide production and demonstrated excellent blood-brain barrier permeability. In vivo studies in aged 5 × FAD mice revealed that D40 significantly reduced neuroinflammation by suppressing pro-inflammatory cytokines and glial activation. Furthermore, D40 mitigated Aβ deposition, promoted neuronal survival, and improved cognitive deficits, while demonstrating a favorable safety profile in acute toxicity evaluations. These findings highlight D40 as a dual-function ChEI capable of providing symptomatic relief and modulating neuroinflammatory pathways associated with AD. With its enhanced cholinesterase inhibition and anti-inflammatory properties, D40 emerges as a promising candidate for the treatment of advanced stages of AD. Acetylcholine deficiency and neuroinflammation as drivers of Alzheimer's disease dually intervened by Compound D40.

Oxidovanadium(IV) Porphyrin-Imidazole Complex-Catalyzed One-Pot, Three-Component Green Synthesis of Biologically Active Pyrano[2,3-d]pyrimidine and 4H-Chromene Heterocycles

A β-functionalized porphyrin ligand {H2TPP(Phen)}, has been synthesized and subsequently employed as a dibasic tetradentate ligand in synthesizing its vanadyl complex 2-(1H-imidazo[4,5-f][1,10]phenanthroline-2-yl)-5,10,15,20-tetraphenylporphyrinatooxido-vanadium(IV)[VIVOTPP(Phen)] (1). Comprehensive characterization of the ligand {H2TPP(Phen)} and its vanadyl(IV) complex (1) was achieved through various analytical and spectroscopic techniques, including NMR, ultraviolet-visible (UV-vis), EPR, and MALDI-TOF mass spectrometry and elemental analysis. Electrochemical studies indicated that the free base porphyrin {H2TPP(Phen)} tends to four successive reduction peaks and two oxidation peaks observed in cyclic voltammetry. In contrast, the metalated complex [VIVOTPP(Phen)] displayed two successive reversible reductions and two oxidation peaks. The synthesized vanadyl(IV)-porphyrin complex (1) was further employed as an efficient and reusable catalyst in an environmentally friendly, one-pot, three-component synthesis of biologically and clinically relevant pyrano[2,3-d]pyrimidine (Ca-Ch, Da-Dg) and 4H-chromene (Ga-Gj, Ha-Hj) heterocycles. Based on the current literature regarding one-pot, multicomponent reactions, two distinct and plausible mechanistic pathways are postulated for these transformations. A detailed mechanistic investigation, including the isolation of intermediates and stepwise reaction analysis, revealed that the type of 1,3-dicarbonyl compound used is pivotal in determining the operative mechanistic pathway in these reactions. The current catalytic protocol developed for the synthesis of pyrano[2,3-d]pyrimidine and 4H-chromene heterocycles presents several advantages over existing methodologies, including the use of an eco-friendly solvent (ethanol), high product yields (up to 97%), shorter reaction time scale (30 min), high turnover frequency (TOF) values (up to 14.7 min-1), and excellent catalyst reusability over five catalytic cycles.

Antioxidants in anti-Alzheimer's disease drug discovery

Oxidative stress is widely recognized as a key contributor to the pathogenesis of Alzheimer's disease (AD). While not the sole factor, it is closely linked to critical pathological features, such as the formation of senile plaques and neurofibrillary tangles. The development of agents with antioxidant properties has become an area of growing interest in AD research. Between 2015 and 2024, several antioxidant-targeted drugs for AD progressed to clinical trials, with increasing attention to the evaluation of antioxidant properties during their development. Oxidative stress plays a pivotal role in linking various AD hypotheses, underscoring its importance in understanding the disease mechanisms. Despite this, comprehensive reviews addressing advancements in AD drug development from the perspective of antioxidant capacity remain limited, hindering the design of novel compounds. This review aims to explore the mechanistic relationship between oxidative stress and AD, summarize methods for assessing antioxidant capacity, and provide an overview of antioxidant compounds with anti-AD properties reported over the past decade. The goal is to offer strategies for identifying effective antioxidant-based therapies for AD and to deepen our understanding of the role of oxidative stress in AD pathology.

Recent Studies on Heterocyclic Cholinesterase Inhibitors Against Alzheimer's Disease

Alzheimer's disease is a progressive and neurodegenerative disease characterized by impairment in emotion, language, memory, and cognitive judgment. There are many factors related to Alzheimer's disease, such as amyloid beta plaques (Aβ) due to impaired metabolism of amyloid precursor protein (APP), tau hyperphosphorylation, and accumulation of neurofibrillary tangles, and disruption of the cholinergic system. Disruption of the cholinergic system responsible for cognitive function and memory processes is one of the important causes of Alzheimer's disease. Therefore, cholinesterase (acetylcholinesterase and butyrylcholinesterase) inhibitors that maintain choline (acetylcholine and butyrylcholine) levels in the synaptic gap play an important role in the symptomatic treatment of Alzheimer's disease. Numerous studies have been carried out against Alzheimer's disease involving acetylcholinesterase and butyrylcholinesterase inhibitors. However, there are very few drugs (tacrine, rivastigmine, galantamine, and donepezil) approved as cholinesterase inhibitors. Therefore, cholinesterase inhibitors are needed against Alzheimer's disease. This review is focused on using heterocyclic rings that show remarkable cholinesterase inhibitory activity for Alzheimer's disease. In this review, chemical structures and structure-activity relationships of recently reported cholinesterase inhibitors are emphasized. This review will give important ideas to medicinal chemists in the discovery and development of potent cholinesterase inhibitors in their future studies.

D30 Alleviates β2-Microglobulin-Facilitated Neurotoxic Microglial Responses in Isoflurane/Surgery-Induced Cognitive Dysfunction in Aged Mice

Postoperative cognitive dysfunction (POCD) is a common complication with no effective treatment in elderly patients. POCD, Alzheimer disease (AD), and many other cognitive diseases mostly involve neurotoxic microglia response, and recently, β2-microglobulin (B2M) has been suggested to play a pivotal role. A novel pyromeconic acid-styrene hybrid compound D30 was synthesized by our team and shown to be safe and effective in some neurodegenerative mouse models. In this study, we evaluated D30 on POCD and its potential mechanism. Fourteen- to 18-month-old male C57BL/6 mice were used to establish POCD through isoflurane anesthesia and surgery. The plasma of elderly patients was collected pre- and postoperatively. Primary mouse microglia were subjected to various stimulations in multiple experimental designs to imitate in vivo POCD-like conditions. Morris water maze, fear conditioning, western blot, immunofluorescent staining, and blood-brain barrier (BBB) permeability tests were conducted in this study. D30 administration significantly improved learning and memory in aged mice following POCD. Neurotoxic M1 microglia cells were dramatically increased following POCD, manifested as morphologically changing into fewer and shorter branches, enlarged somatic areas, and upregulated expression of iNOS and C1q. Notably, following POCD, B2M was significantly upregulated in the plasma and the brain. D30 treatment significantly suppressed these pathologic changes, by inhibiting the POCD-induced BBB breakdown while suppressing the surge of plasma B2M levels. D30 treatment suppressed POCD-induced surge of B2M and Aβ plaques in the brain and preserved adult hippocampal neurogenesis vulnerable to POCD. Furthermore, postoperative levels of B2M were significantly elevated over the preoperative levels in patients aged 80 years and over. In parallel with mouse plasma after POCD, the postoperative patient plasma was also much more effective at activating M1 microglia. Of note, this POCD plasma-induced activation of M1 microglia was largely prevented by D30 treatment. Taken together, by inhibiting the surge of plasma B2M, protecting BBB integrity, and reducing inflammatory response, D30 protected aged mice from B2M-facilitated POCD.

Design, synthesis and biological evaluation of novel pyrazolinone derivatives as multifunctional ligands for the treatment of Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by the depletion of cholinergic neurons and the accumulation of amyloid β (Aβ) plaques. The complexity and multifaceted nature of AD necessitate further exploration of multi-target drugs for its treatment. In this study, a series of novel pyrazolinone-based compounds were designed, synthesized, and evaluated as acetylcholinesterase (AChE) inhibitors and antioxidants. The lead compounds ET11 and ET21 showed strong inhibitory activity against human AChE, with IC50 values of 6.34 and 1.81 nM, respectively. In vitro DPPH and ORACFL assays confirmed the compounds' strong antioxidant capabilities. ET11 exhibited excellent neuroprotective activity in the tBHP-induced SH-SY5Y cell damage model. Benefiting from the pyridopyrazolone moiety, ET11 showed significant Cu2+ chelating ability and effectively inhibited Cu2+-induced Aβ aggregation. In vivo behavioral studies and histopathology analysis preliminarily confirmed the compound's cognitive improvement and neuroprotective effects. Overall, these findings suggested that compound ET11 is expected to play a synergistic role in the treatment of AD, potentially slowing disease progression.

Novel anti-neuroinflammatory pyranone-carbamate derivatives as selective butyrylcholinesterase inhibitors for treating Alzheimer's disease

Butyrylcholinesterase (BuChE) and neuroinflammation have recently emerged as promising therapeutic directions for Alzheimer's disease (AD). Herein, we synthesised 19 novel pyranone-carbamate derivatives and evaluated their activities against cholinesterases and neuroinflammation. The optimal compound 7p exhibited balanced BuChE inhibitory activity (eqBuChE IC50 = 4.68 nM; huBuChE IC50 = 9.12 nM) and anti-neuroinflammatory activity (NO inhibition = 28.82% at 10 μM, comparable to hydrocortisone). Enzyme kinetic and docking studies confirmed compound 7p was a mix-type BuChE inhibitor. Additionally, compound 7p displayed favourable drug-likeness properties in silico prediction, and exhibited high BBB permeability in the PAMPA-BBB assay. Compound 7p had good safety in vivo as verified by an acute toxicity assay (LD50 > 1000 mg/kg). Most importantly, compound 7p effectively mitigated cognitive and memory impairments in the scopolamine-induced mouse model, showing comparable effects to Rivastigmine. Therefore, we envisioned that compound 7p could serve as a promising lead compound for treating AD.

Compound (E)-2-(3,4-dihydroxystyryl)-3-hydroxy-4H-pyran-4-one downregulation of Galectin-3 ameliorates Aβ pathogenesis-induced neuroinflammation in 5 × FAD mice

AIMS

Alzheimer's disease (AD) is characterized by β-amyloid (Aβ) aggregation and neuroinflammation, leading to progressive synaptic loss and cognitive decline. Recent evidence suggests that Galectin-3 (Gal-3) plays a critical role in Aβ pathogenesis. However, strategies to simultaneously target Gal-3 and Aβ are currently insufficient. This study evaluates the therapeutic efficacy of (E)-2-(3,4-dihydroxystyryl)-3-hydroxy-4H-pyran-4-one (D30), in reducing Gal-3 and Aβ pathogenesis.

MATERIALS AND METHODS

We applied exogenous oligomeric Aβ and used 5 × FAD mice to assess the impact of Aβ on Gal-3 deposition, microglial activation, and cognitive function. Thy1-EGFP mice were employed to observe dendritic spines. Comprehensive evaluations of D30's effects included behavioral studies, transcriptomic analysis, Western blotting, and immunofluorescent staining. The interaction between D30 and Gal-3 was examined using fluorescence resonance energy transfer (FRET) and microscale thermophoresis (MST).

KEY FINDINGS

D30 effectively reduced Aβ monomer production by inhibiting Amyloid Precursor Protein (APP) and presenilin 1 (PS1) expression, and decreased Aβ aggregation. Treatment with D30 improved cognitive functions, reversed dendritic spine loss, and increased PSD95 expression in 5 × FAD mice. Additionally, D30 significantly lowered Gal-3 levels in both plasma and hippocampal tissues. D30 binds to Gal-3 and disrupts the interaction between Gal-3 and TREM2, as confirmed by FRET and MST.

SIGNIFICANCE

Our findings underscore the interaction between Gal-3 and Aβ in AD and its role in systemic inflammation using the 5 × FAD mouse model. Being able to target and regulate Gal-3 together with Aβ is crucial for preventing neuroinflammation and protecting synapses, D30 emerged as a novel compound with promising potential for AD treatment.

Synthesis, biological evaluation, molecular docking, MD simulation and DFT analysis of new 3-hydroxypyridine-4-one derivatives as anti-tyrosinase and antioxidant agents

In the present study, ten new substituted 3-hydroxypyridine-4-one derivatives were synthesized in a four-step method, and their chemical structures were confirmed using various spectroscopic techniques. Subsequently, the inhibitory activities of these derivatives against tyrosinase enzyme and their antioxidant activities were evaluated. Amongest the synthesized compounds, 6b bearing a 4-OH-3-OCH3 substitution was found to be a promising tyrosinase inhibitor with an IC50 value of 25.82 μM, which is comparable to the activity of kojic acid as control drug. Kinetic study indicated that compound 6b is a competitive inhibitor of tyrosinase enzyme, which was confirmed by molecular docking results. The molecular docking study and MD simulation showed that compound 6b was properly placed within the tyrosinase binding pocket and interacted with key residues, which is consistent with its biological activity. The DFT analysis demonstrated that compound 6b is kinetically more stable than the other compounds. In addition, compounds 6a and 6b exhibited the best antioxidant activities. The findings indicate that compound 6b could be a promising lead for further studies.

Discovery of novel deoxyvasicinone derivatives with benzenesulfonamide substituents as multifunctional agents against Alzheimer's disease

A series of deoxyvasicinone derivatives with benzenesulfonamide substituents were designed and synthesized to find a multifunctional anti-Alzheimer's disease (AD) drug. The results of the biological activity evaluation indicated that most compounds demonstrated selective inhibition of acetylcholinesterase (AChE). Among them, g17 exhibited the most potent inhibitory effect on AChE (IC50 = 0.24 ± 0.04 μM). Additionally, g17 exhibited promising properties as a metal chelator and inhibitor of amyloid β peptides self-aggregation (68.34 % ± 1.16 %). Research on oxidative stress has shown that g17 displays neuroprotective effects and effectively suppresses the intracellular accumulation of reactive oxygen species. Besides, g17 demonstrated remarkable anti-neuroinflammatory effects by significantly reducing the production of pro-inflammatory cytokines (such as NO, IL-1β, and TNF-α) and inhibiting the expression of inflammatory mediators iNOS and COX-2. In vivo studies showed that g17 significantly improved AD model mice's cognitive and memory abilities. Histological examination of mouse hippocampal tissue sections using hematoxylin and eosin staining revealed that g17 effectively mitigates neuronal damage. Considering the multifunctional properties of g17, it is regarded as a promising lead compound for treating AD.

Recent Advancements in the Treatment of Alzheimer's Disease: A Multitarget-directed Ligand Approach

Alzheimer's disease (AD) is a neurodegenerative disease and one of the leading causes of progressive dementia, affecting 50 million people worldwide. Many pathogenic processes, including amyloid β aggregation, tau hyperphosphorylation, oxidative stress, neuronal death, and deterioration of the function of cholinergic neurons, are associated with its progression. The one-compound-one-target treatment paradigm was unsuccessful in treating AD due to the multifaceted nature of Alzheimer's disease. The recent development of multitarget-directed ligand research has been explored to target the complementary pathways associated with the disease. We aimed to find the key role and progress of MTDLs in treating AD; thus, we searched for the past ten years of literature on "Pub- Med", "ScienceDirect", "ACS" and "Bentham Science" using the keywords neurodegenerative diseases, Alzheimer's disease, and multitarget-directed ligands. The literature was further filtered based on the quality of work and relevance to AD. Thus, this review highlights the current advancement and advantages of multitarget-directed ligands over traditional single-targeted drugs and recent progress in their development to treat AD.