Dual targeting of acetylcholinesterase and tau aggregation: Design, synthesis and evaluation of multifunctional deoxyvasicinone analogues for Alzheimer's disease

Deoxyvasicinone hybrids in the management of Alzheimer's disease: Recent advances on manmade derivatives, pharmacological activities, and structure-activity relationship

Alzheimer's disease (AD) is a prevalent neurological illness that affects over 80% of aged adults globally in cases of dementia. Although the exact pathophysiological causes of AD remain unclear, its pathogenesis is primarily driven by several distinct biochemical alterations: (i) the accumulation of toxic Aβ plaques, (ii) the hyperphosphorylation of tau proteins, (iii) oxidative stress resulting in cell death, and (iv) an imbalance between the two main neurotransmitters, glutamate and acetylcholine (ACh). Currently, there are very few medications available and no treatment. Presently marketed medications include memantine, an N-methyl-d-aspartate receptor (NMDA) antagonist, and acetylcholinesterase (AChE) inhibitors: rivastigmine, donepezil, and galantamine. Unfortunately, these medications are only useful in the initial stages of AD. The mentioned medications only provide symptomatic relief and do not slow down the disease progression in the advanced stages. Therefore, there is an urgent need to develop potential candidates to treat AD, symptomatically and therapeutically. Many research groups focus on natural products due to their diverse therapeutic profiles and easy availability. One such natural product is deoxyvasicinone, isolated from Adhatoda vasica. Given its broad pharmacological profile, various researchers have developed semisynthetic hybrids of deoxyvasicinone to address multifaceted diseases like AD. In this review article, we tried to summarize the semisynthetic hybrids of deoxyvasicinone developed over the past decade (2014-2024) for managing AD. We focus on their design, pharmacological activity, and structure-activity relationship (SAR) analysis. We hope this review enhances the reader's understanding of future exploratory options for deoxyvasicinone hybrids in AD management.

Progress in the study of anti-Alzheimer's disease activity of pyrimidine-containing bioactive molecules

Pyrimidines are aromatic, heterocyclic organic compounds characterized by a six-membered ring that contains four carbon atoms and two nitrogen atoms. They have been reported to exhibit a variety of biological activities such as antifungal, antiviral, and anti-Parkinsonian effects. Recently, there has been an increased focus on their potential anti-Alzheimer's properties. Several pyrimidine-based drugs and their analogs are currently undergoing various phases of clinical trials, indicating pyrimidine as a promising chemical structure for drug development. Notably, modifications to the pyrimidine structure significantly influence their activity against Alzheimer's disease. For instance, the introduction of heteroatoms into the pyrimidine ring or alternations in the length of the linkage region have been shown to enhance therapeutic efficacy. This review provides a comprehensive overview of pyrimidine derivatives as potential therapeutics for Alzheimer's disease, with a focus on structure-activity relationship (SAR) studies, design strategies, and binding mechanisms. These insights could pave the way for the development of more effective anti-Alzheimer's medications.

Alkaloids from Mackinlaya species and synthetic mackinazolinone derivatives: An overview

Mackinazolinone is the main alkaloid isolated from plants of the genus Mackinlaya, essentially distributed in tropical Asia and Australia. There are five Mackinlaya species all containing bioactive alkaloids with a tetrahydropyridoquinazolinone core such as mackinazoline (1) and mackinazolinone (2). The present review retraces the origin of mackinazolinone and compares the different chemical routes to synthesize the natural product, through different methods including classical batch synthesis, solid-phase supported synthesis, microwaved irradiation and photochemistry. A panel of about 70 mackinazolinone analogues and derivatives is presented to illustrate the diversity of chemical approaches and structures. The pharmacology of mackinazolinone has been little investigated but derivatives with antibacterial or anticancer properties have been identified. The molecular targets for these compounds are essentially unknown, but a few proteins of interest have been evoked occasionally, such as the EGFR kinase. The natural product mackinazolinone has largely inspired chemists to develop novel products and chemical processes. Hopefully, the review will now encourage pharmacologists to further explore the properties of these quinazolinones as potential anti-infectious, anticancer and/or neuroprotective agents.

From Fundamentals to Innovation in Alzheimer's Disease: Molecular Findings and Revolutionary Therapies

Alzheimer's disease (AD) is a global health concern and the leading cause of dementia in the elderly. The prevalence of this neurodegenerative condition is projected to increase concomitantly with increased life expectancy, resulting in a significant economic burden. With very few FDA-approved disease-modifying drugs available for AD, there is an urgent need to develop new compounds capable of impeding the progression of the disease. Given the unclear etiopathogenesis of AD, this review emphasizes the underlying mechanisms of this condition. It explores not only well-studied aspects, such as the accumulation of Aβ plaques and neurofibrillary tangles, but also novel areas, including glymphatic and lymphatic pathways, microbiota and the gut-brain axis, serotoninergic and autophagy alterations, vascular dysfunction, the metal hypothesis, the olfactory pathway, and oral health. Furthermore, the potential molecular targets arising from all these mechanisms have been reviewed, along with novel promising approaches such as nanoparticle-based therapy, neural stem cell transplantation, vaccines, and CRISPR-Cas9-mediated genome editing techniques. Taking into account the overlap of these various mechanisms, individual and combination therapies emerge as the future direction in the AD strategy.

Access to N-Fused Quinazolinones by Radical-Promoted Cascade Annulations of Alkenyl N-Cyanamides with Aromatic Aldehydes

A cascade radical cyclization of alkenyl N-cyanamides with aromatic aldehydes has been achieved for an expeditious synthesis of keto-methylated dihydropyrrolo-quinazolinones. Benzoyl radicals, generated from aryl aldehydes in the presence of di-tert-butyl peroxide (DTBP), promoted the domino annulations leading to distinctive functionalized quinazolinones in good yields. In addition, the robustness of the present protocol is validated by employing heterocyclic and natural product-based aldehydes.

Synthesis and Biological Activity of Some Bromophenols and Their Derivatives Including Natural Products

In addition to the first synthesis of the natural bromophenol butyl 2-(3,5-dibromo-4-hydroxyphenyl)acetate (1), indene derivatives 34 and 35 were synthesized from 3-phenylpropenal derivatives in BBr3 medium. Five known natural bromophenols and some derivatives were synthesized by known methods. Cholinesterase (ChEs) inhibitors reduce the breakdown of acetylcholine and are used in the treatment of Alzheimer's disease (AD) and dementia symptoms. The inhibition effects of all obtained compounds were examined towards acetylcholinesterase (AChE), butyrylcholinesterase (BChE) and α-glycosidase enzymes. All synthesized compounds demonstrated the strong inhibition effects against both cholinergic enzymes. For determination of Ki values of novel bromophenols Lineweaver-Burk graphs were obtained. Ki values were found in the ranging of 0.13-14.74 nM for AChE, 5.11-23.95 nM for BChE, and 63.96-206.78 nM for α-glycosidase, respectively. All bromophenols and their derivatives exhibit effective inhibition profile when compared to positive controls.

Multicomponent Petasis reaction for the identification of pyrazine based multi-target directed anti-Alzheimer's agents: In-silico design, synthesis, and characterization

Multi-target directed ligands (MTDLs) have recently attracted significant interest due to their exceptional effectiveness against multi-factorial Alzheimer's disease. The present work described the development of pyrazine-based MTDLs using multicomponent Petasis reaction for the dual inhibition of tau-aggregation and human acetylcholinesterase (hAChE). The molecular structure of synthesized ligands was validated by ¹H & ¹³C NMR and mass spectrometry. The screened compounds were shown to have a strong inhibitory effect at 10 μM concentration against tau-oligomerization and hAChE, but only moderate inhibitory activity against Aβ₄₂. Among all the compounds, the half-maximal inhibitory concentration (IC₅₀) for 21 and 24 against hAChE were 0.71 μM and 1.09 μM, respectively, while they displayed half-maximal effective concentrations (EC₅₀) values of 2.21 μM and 2.71 μM for cellular tau-oligomerization, respectively. Additionally, an MTT experiment using tau-expressing SH-SY5Y neuroblastoma cells revealed that 21 was more neuroprotective than the FDA-approved medication donepezil. Furthermore, an MD simulation study was performed to investigate the dynamics and stability of AChE-21 and AChE-24 complexes in an aqueous environment. The MM-PBSA calculations were performed to evaluate the binding of 21 and 24 with AChE, and the relative binding energy was calculated as -870.578 and -875.697 kJ mol^-1, respectively. As a result, the study offered insight into the design of new MTDLs and highlighted 21 as a potential roadblock to the development of anti-AD medications.

Beyond the classical amyloid hypothesis in Alzheimer's disease: Molecular insights into current concepts of pathogenesis, therapeutic targets, and study models

Alzheimer's disease (AD) is one of the progressive neurodegenerative disorders and the most common cause of dementia in the elderly worldwide causing difficulties in the daily life of the patient. AD is characterized by the aberrant accumulation of β-amyloid plaques and tau protein-containing neurofibrillary tangles (NFTs) in the brain giving rise to neuroinflammation, oxidative stress, synaptic failure, and eventual neuronal cell death. The total cost of care in AD treatment and related health care activities is enormous and pharmaceutical drugs approved by Food and Drug Administration have not manifested sufficient efficacy in protection and therapy. In recent years, there are growing studies that contribute a fundamental understanding to AD pathogenesis, AD-associated risk factors, and pharmacological intervention. However, greater molecular process-oriented research in company with suitable experimental models is still of the essence to enhance the prospects for AD therapy and cell lines as a disease model are still the major part of this milestone. In this review, we provide an insight into molecular mechanisms, particularly the recent concept in gut-brain axis, vascular dysfunction and autophagy, and current models used in the study of AD. Here, we emphasized the importance of therapeutic strategy targeting multiple mechanisms together with utilizing appropriate models for the discovery of novel effective AD therapy. This article is categorized under: Neurological Diseases > Molecular and Cellular Physiology.

Synthesis and Pharmacological Evaluation of Novel Triazole-Pyrimidine Hybrids as Potential Neuroprotective and Anti-neuroinflammatory Agents

OBJECTIVE

Neuroprotection is a precise target for the treatment of neurodegenerative diseases, ischemic stroke, and traumatic brain injury. Pyrimidine and its derivatives have been proven to use antiviral, anticancer, antioxidant, and antimicrobial activity prompting us to study the neuroprotection and anti-inflammatory activity of the triazole-pyrimidine hybrid on human microglia and neuronal cell model.

METHODS

A series of novel triazole-pyrimidine-based compounds were designed, synthesized and characterized by mass spectra, 1HNMR, 13CNMR, and a single X-Ray diffraction analysis. Further, the neuroprotective, anti-neuroinflammatory activity was evaluated by cell viability assay (MTT), Elisa, qRT-PCR, western blotting, and molecular docking.

RESULTS

The molecular results revealed that triazole-pyrimidine hybrid compounds have promising neuroprotective and anti-inflammatory properties. Among the 14 synthesized compounds, ZA3-ZA5, ZB2-ZB6, and intermediate S5 showed significant anti-neuroinflammatory properties through inhibition of nitric oxide (NO) and tumor necrosis factor-α (TNF-α) production in LPS-stimulated human microglia cells. From 14 compounds, six (ZA2 to ZA6 and intermediate S5) exhibited promising neuroprotective activity by reduced expression of the endoplasmic reticulum (ER) chaperone, BIP, and apoptosis marker cleaved caspase-3 in human neuronal cells. Also, a molecular docking study showed that lead compounds have favorable interaction with active residues of ATF4 and NF-kB proteins.

CONCLUSION

The possible mechanism of action was observed through the inhibition of ER stress, apoptosis, and the NF-kB inflammatory pathway. Thus, our study strongly indicates that the novel scaffolds of triazole-pyrimidine-based compounds can potentially be developed as neuroprotective and anti-neuroinflammatory agents.

Insights into the chemistry and therapeutic potential of acrylonitrile derivatives

Acrylonitrile is a fascinating scaffold widely found in many natural products, drugs, and drug candidates with various biological activities. Several drug molecules such as entacapone, rilpivirine, teriflunomide, and so forth, bearing an acrylonitrile moiety have been marketed. In this review, diverse synthetic strategies for constructing desired acrylonitriles are discussed, and the different biological activities and medicinal significance of various acrylonitrile derivatives are critically evaluated. The information gathered is expected to provide rational guidance for the development of clinically useful agents from acrylonitriles.