Novel sarsasapogenin-triazolyl hybrids as potential anti-Alzheimer's agents: Design, synthesis and biological evaluation

Analysis of skeletal diversity of multi-target directed ligands (MTDLs) targeting Alzheimer's disease

Alzheimer's disease (AD) remains a significant healthcare challenge, necessitating innovative therapeutic approaches to address its complex and multifactorial nature. Traditional drug discovery strategies targeting single molecular targets are not sufficient for the effective treatment of AD. In recent years, MTDLs have emerged as promising candidates for AD therapy, aiming to simultaneously modulate multiple pathological targets. Among the various strategies employed in MTDL design, pharmacophore hybridization offers a versatile approach to integrate diverse pharmacophoric features within a single molecular scaffold. This strategy provides access to a wide array of chemical space for the design and development of novel therapeutic agents. This review, therefore, provides a comprehensive overview of skeletal diversity exhibited by MTDLs designed recently for AD therapy based on pharmacophore hybridization approach. A diverse range of pharmacophoric elements and core scaffolds hybridized to construct MTDLs that has the potential to target multiple pathological features of AD including amyloid-beta aggregation, tau protein hyperphosphorylation, cholinergic dysfunction, oxidative stress, and neuroinflammation are discussed. Through the comprehensive analysis and integration of structural insights of key biomolecular targets, this review aims to enhance optimization efforts in MTDL design, ultimately striving towards a comprehensive cure for the multifaceted pathophysiology of the disease.

Repurposing Anidulafungin for Alzheimer's Disease via Fragment-Based Drug Discovery

The misfolding and aggregation of beta-amyloid (Aβ) peptides have been implicated as key pathogenic events in the early stages of Alzheimer's disease (AD). Inhibiting Aβ aggregation represents a potential disease-modifying therapeutic approach to AD treatment. Previous studies have identified various molecules that inhibit Aβ aggregation, some of which share common chemical substructures (fragments) that may be key to their inhibitory activity. Employing fragment-based drug discovery (FBDD) methods may facilitate the identification of these fragments, which can subsequently be used to screen new inhibitors and provide leads for further drug development. In this study, we used an in silico FBDD approach to identify 17 fragment clusters that are significantly enriched among Aβ aggregation inhibitors. These fragments were then used to screen anti-infective agents, a promising drug class for repurposing against amyloid aggregation. This screening process identified 16 anti-infective drugs, 5 of which were chosen for further investigation. Among the 5 candidates, anidulafungin, an antifungal compound, showed high efficacy in inhibiting Aβ aggregation in vitro. Kinetic analysis revealed that anidulafungin selectively blocks the primary nucleation step of Aβ aggregation, substantially delaying Aβ fibril formation. Cell viability assays demonstrated that anidulafungin can reduce the toxicity of oligomeric Aβ on BV2 microglia cells. Molecular docking simulations predicted that anidulafungin interacted with various Aβ species, including monomers, oligomers, and fibrils, potentially explaining its activity against Aβ aggregation and toxicity. This study suggests that anidulafungin is a potential drug to be repurposed for AD, and FBDD is a promising approach for discovering drugs to combat Aβ aggregation.

Extraction, isolation, synthesis, and biological evaluation of novel piperic acid derivatives for the treatment of Alzheimer's disease

In this paper, we developed a series of piperic acid (PA) analogs with the aim of overcoming the limitations associated with the natural products for the management of Alzheimer's disease (AD). A comprehensive SAR study was performed to enhance cholinesterase inhibition of PA. The acetylcholinesterase inhibition and its kinetic data suggested 6j as the lead molecule (AChE IC50 = 2.13 ± 0.015 µM, BChE = 28.19 ± 0.20%), in comparison to PA (AChE = 7.14 ± 0.98%) which was further selected for various biological studies in AD models. 6j, exhibited interaction with the peripheral anionic site of AChE, BBB permeability (Pe = 7.98), and antioxidant property (% radical scavenging activity = 35.41 ± 1.09, 2.43 ± 1.65, for 6j and PA at 20 M μ , respectively). The result from the metal chelation study suggests that 6j did not effectively chelate iron. The molecular modeling studies suggested that 6j could effectively interact with Ser293, Phe295, Arg296, and Tyr34 of AChE. In the cell-based cytotoxicity studies, 6j exhibited cytocompatibility at the different tested concentrations. The acute toxicity data on mice suggested that compound 6j had no renal and hepatotoxicity at 500 mg/kg. Moreover, 6j could effectively reverse scopolamine-induced amnesia by improving spatial and cognitive memory in mice. The above results strongly suggest that compound 6j may act as a novel multi-targeted lead for AD therapy.

Sarsasapogenin regulates the immune microenvironment through MAPK/NF-kB signaling pathway and promotes functional recovery after spinal cord injury

Spinal cord injury (SCI) occurs as a result of traumatic events that damage the spinal cord, leading to motor, sensory, or autonomic function impairment. Sarsasapogenin (SA), a natural steroidal compound, has been reported to have various pharmacological applications, including the treatment of inflammation, diabetic nephropathy, and neuroprotection. However, the therapeutic efficacy and underlying mechanisms of SA in the context of SCI are still unclear. This research aimed to investigate the therapeutic effects and mechanisms of SA against SCI by integrating network pharmacology analysis and experimental verification. Network pharmacology results suggested that SA may effectively treat SCI by targeting key targets such as TNF, RELA, JUN, MAPK14, and MAPK8. The underlying mechanism of this treatment may involve the MAPK (JNK) signaling pathway and inflammation-related signaling pathways such as TNF and Toll-like receptor signaling pathways. These findings highlight the therapeutic potential of SA in SCI treatment and provide valuable insights into its molecular mechanisms of action. In vivo experiments confirmed the reparative effect of SA on SCI in rats and suggested that SA could repair SCI by modulating the immune microenvironment. In vitro experiments further investigated how SA regulates the immune microenvironment by inhibiting the MAPK/NF-kB pathways. Overall, this study successfully utilized a combination of network pharmacology and experimental verification to establish that SA can regulate the immune microenvironment via the MAPK/NF-kB signaling pathway, ultimately facilitating functional recovery from SCI. Furthermore, these findings emphasize the potential of natural compounds from traditional Chinese medicine as a viable therapy for SCI treatment.

Investigation of new 1,2,3-triazolyl-quinolinyl-propan-2-ol derivatives as potential antimicrobial agents: in vitro and in silico approach

A new series of 1-((1-(4-substituted benzyl)-1H-1,2,3-triazol-4-yl)methoxy)-2-(2-substituted quinolin-4-yl)propan-2-ol (9a-x) have been synthesized. The newly synthesized 1,2,3-triazolyl-quinolinyl-propan-2-ol (9a-x) derivatives were screened for in vitro antimicrobial activity against M. tuberculosis H37Rv, E. coli, P. mirabilis, B. subtilis, and S. albus. Most of the compounds showed good to moderate antibacterial activity and all derivatives have shown excellent to good antitubercular activity with MIC 0.8-12.5 μg/mL. To know the plausible mode of action for antibacterial activity the docking study against DNA gyrase from M. tuberculosis and S. aureus was investigated. The compounds have shown significant docking scores in the range of -9.532 to -7.087 and -9.543 to -6.621 Kcal/mol with the DNA gyrase enzyme of S. aureus (PDB ID: 2XCT) and M. tuberculosis (PDB ID: 5BS8), respectively. Against the S. aureus and M. tuberculosis H37Rv strains, the compound 9 l showed good activity with MIC values of 62.5 and 3.33 μM. It also showed significant docking scores in both targets with -8.291 and -8.885 Kcal/mol, respectively. Molecular dynamics was studied to investigate the structural and dynamics transitions at the atomistic level in S. aureus DNA gyrase (2XCT) and M. tuberculosis DNA gyrase (5BS8). The results revealed that the residues in the active binding pockets of the S. aureus and M. tuberculosis DNA gyrase proteins that interacted with compound 9 l remained relatively consistent throughout the MD simulations and thus, reflected the conformation stability of the respective complexes. Thus, the significant antimicrobial activity of derivatives 9a-x recommended that these compounds could assist in the development of lead compounds to treat for bacterial infections.Communicated by Ramaswamy H. Sarma.

Research progress of natural products and their derivatives against Alzheimer's disease

Alzheimer's disease (AD), a persistent neurological dysfunction, has an increasing prevalence with the aging of the world and seriously threatens the health of the elderly. Although there is currently no effective treatment for AD, researchers have not given up, and are committed to exploring the pathogenesis of AD and possible therapeutic drugs. Natural products have attracted considerable attention owing to their unique advantages. One molecule can interact with multiple AD-related targets, thus having the potential to be developed in a multi-target drug. In addition, they are amenable to structural modifications to increase interaction and decrease toxicity. Therefore, natural products and their derivatives that ameliorate pathological changes in AD should be intensively and extensively studied. This review mainly presents research on natural products and their derivatives for the treatment of AD.

Mechanistic inhibition of gastric cancer-associated bacteria Helicobacter pylori by selected phytocompounds: A new cutting-edge computational approach

Background

Helicobacter pylori (H. pylori) is a persistent bacterial inhabitant in the stomachs of approximately half the global populace. This bacterium is directly linked to chronic gastritis, leading to a heightened risk of duodenal and gastric ulcer diseases, and is the predominant risk factor for gastric cancer - the second most common cause of cancer-related deaths globally. The increasing prevalence of antibiotic resistance necessitates the exploration of innovative treatment alternatives to mitigate the H. pylori menace.

Methods

Initiating our study, we curated a list of thirty phytochemicals based on previous literature and subjected them to molecular docking studies. Subsequently, eight phytocompounds-Glabridin, Isoliquiritin, Sanguinarine, Liquiritin, Glycyrrhetic acid, Beta-carotin, Diosgenin, and Sarsasapogenin-were meticulously chosen based on superior binding scores. These were further subjected to an extensive computational analysis encompassing ADMET profiling, drug-likeness evaluation, principal component analysis (PCA), and molecular dynamic simulations (MDs) in comparison with the conventional drug, Mitomycin.

Results

The natural compounds investigated demonstrated superior docking affinities to H. pylori targets compared to the standard Mitomycin. Notably, the phytocompounds Diosgenin and Sarsasapogenin stood out due to their exceptional binding affinities and pharmacokinetic properties, including favorable ADMET profiles.

Conclusion

Our comprehensive and technologically-advanced approach showcases the potential of identified phytocompounds as pioneering therapeutic agents against H. pylori-induced gastric malignancies. In light of our promising in silico results, we recommend these natural compounds as potential candidates for advancing H. pylori-targeted drug development. Given their potential, we strongly advocate for subsequent in vitro and in vivo studies to validate their therapeutic efficacy against this formidable gastrointestinal bacterium.

Pathogenesis of Alzheimer's Disease and Diversity of 1,2,3-Triazole Scaffold in Drug Development: Design Strategies, Structural Insights, and Therapeutic Potential

Alzheimer's disease is a most prevalent form of dementia all around the globe and currently poses a significant challenge to the healthcare system. Currently available drugs only slow the progression of this disease rather than provide proper containment. Identification of multiple targets responsible for this disease in the last three decades established it as a multifactorial neurodegenerative disorder that needs novel multifunctional agents for its management and the possible reason for the failure of currently available single target clinical drugs. 1,2,3-Triazole is a miraculous nucleus in medicinal chemistry and the first choice for development of multifunctional hybrid molecules. Apart from that, it is an integral component of various drugs in clinical trials as well as in clinical practice. This review is focused on the pathogenesis of Alzheimer's disease and 1,2,3-triazole containing derivatives developed in recent decades as potential anti-Alzheimer's agents. The review will provide (A) precise insight of various established targets of Alzheimer's disease including cholinergic, amyloid, tau, monoamine oxidases, glutamate, calcium, and reactive oxygen species hypothesis and (B) design hypothesis, structure-activity relationships, and pharmacological outcomes of 1,2,3-triazole containing multifunctional anti-Alzheimer's agents. This review will provide a baseline for various research groups working on Alzheimer's drug development in designing potent, safer, and effective multifunctional anti-Alzheimer's candidates of the future.

Review of triazole scaffolds for treatment and diagnosis of Alzheimer's disease

Triazole scaffolds, a series of 5-membered heterocycles, are well known for their high efficacy, low toxicity, and superior pharmacokinetics. Alzheimer's disease (AD) is the first neurodegenerative disorder with complex pathological mechanisms. Triazole, as an aromatic group with three nitrogen atoms, forms polar and non-polar interactions with diverse key residues in the receptor-ligand binding procedure, and has been widely used in the molecular design in the development of anti-AD agents. Moreover, considering the simple synthesis approaches, triazole scaffolds are commonly used to link two pharmacodynamic groups in one chemical molecule, forming multi-target directed ligands (MTDLs). Furthermore, the click reaction between azide- and cyano-modified enzyme and ligand provides feasibility for the new modulator discovery, compound tissue distribution evaluation, enzyme localization, and pharmacological mechanism study, promoting the diagnosis of AD course.

A minireview of 1,2,3-triazole hybrids with O-heterocycles as leads in medicinal chemistry

Over the past few decades, the dynamic progress in the synthesis and screening of heterocyclic compounds against various targets has made a significant contribution in the field of medicinal chemistry. Among the wide array of heterocyclic compounds, triazole moiety has attracted the attention of researchers owing to its vast therapeutic potential and easy preparation via copper and ruthenium-catalyzed azide-alkyne cycloaddition reactions. Triazole skeletons are found as major structural components in a different class of drugs possessing diverse pharmacological profiles including anti-cancer, anti-bacterial, anti-fungal, anti-viral, anti-oxidant, anti-inflammatory, anti-diabetic, anti-tubercular, and anti-depressant among various others. Furthermore, in the past few years, a significantly large number of triazole hybrids were synthesized with various heterocyclic moieties in order to gain the added advantage of the improved pharmacological profile, overcoming the multiple drug resistance and reduced toxicity from molecular hybridization. Among these synthesized triazole hybrids, many compounds are available commercially and used for treating different infections/disorders like tazobactam and cefatrizine as potent anti-bacterial agents while isavuconazole and ravuconazole as anti-fungal activities to name a few. In this review, we will summarize the biological activities of various 1,2,3-triazole hybrids with copious oxygen-containing heterocycles as lead compounds in medicinal chemistry. This review will be very helpful for researchers working in the field of molecular modeling, drug design and development, and medicinal chemistry.

Therapeutic effect and mechanism of Anemarrhenae Rhizoma on Alzheimer’s disease based on multi-platform metabolomics analyses

Anemarrhenae Rhizoma (AR) has multiple pharmacological activities to prevent and treat Alzheimer’s disease (AD). However, the effect and its molecular mechanism are not elucidated clear. This study aims to evaluate AR’s therapeutic effect and mechanism on AD model rats induced by D-galactose and AlCl₃ with serum metabolomics. Behavior study, histopathological observations, and biochemical analyses were applied in the AD model assessment. Gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-QTOF/MS) were combined with multivariate statistical analysis to identify potential biomarkers of AD and evaluate the therapeutic effect of AR on AD from the perspective of metabolomics. A total of 49 biomarkers associated with the AD model were identified by metabolomics, and pathway analysis was performed to obtain the metabolic pathways closely related to the model. With the pre-treatment of AR, 32 metabolites in the serum of AD model rats were significantly affected by AR compared with the AD model group. The regulated metabolites affected by AR were involved in the pathway of arginine biosynthesis, arginine and proline metabolism, ether lipid metabolism, glutathione metabolism, primary bile acid biosynthesis, and steroid biosynthesis. These multi-platform metabolomics analyses were in accord with the results of behavior study, histopathological observations, and biochemical analyses. This study explored the therapeutic mechanism of AR based on multi-platform metabolomics analyses and provided a scientific basis for the application of AR in the prevention and treatment of AD.

Pharmacological exploration of triazole based therapeutics for Alzheimer disease: An overview

Abstract:

Alzheimer`s disease (AD) is an irreversible progressive neurodegenerative disorder which may account for approximately 60-70% cases of dementia worldwide. AD is characterized by impaired behavioural and cognitive functions including memory, language, conception, attentiveness, judgment, and reasoning problems. The two important hallmarks of AD are the appearance of plaques and tangles of amyloid beta (Aβ) and tau proteins, respectively, in the brain based on the etiology of the disease including cholinergic impairment, metal dyshomeostasis, oxidative stress, and degradation of neurotransmitters. Currently, the used medication only provides alleviation of symptoms but not effective in curing the disease that is creating by an urge to develop new molecules to treat AD. Heterocyclic compounds have proven their ability to be developed as drugs for the treatment of various diseases. The five-membered heterocyclic compound triazole has received foremost fascination for the discovery of new drugs due to the possibility of structural variation and proved its significance in various drug categories. Therefore, this review summarizes mainly the recent advancements in the development of novel 1,2,3-triazole and 1,2,4-triazole based molecules in the drug discovery process for targeting various AD targets such as phosphodiesterase 1 (PDE1) Inhibitors, Apoptosis signal-regulating kinase 1 (ASK1) inhibitors, Somatostatin receptor subtype-4 (SSTR4) agonist, many other druggable targets, molecular modelling studies as well as various methodology for the synthesis of triazoles containing molecules such as Click reaction, Pellizzari and Einhorn-Brunner Reaction.

Developments in the Antitumor Activity, Mechanisms of Action, Structural Modifications, and Structure-Activity Relationships of Steroidal Saponins

Steroidal saponins, a class of natural products formed by the combination of spirosteranes with sugars, are widely distributed in plants and have various biological activities, such as anti-tumor, anti-inflammatory, anti-bacterial, anti-Alzheimer's, anti-oxidation, etc. Particularly, extensive researches on the antitumor property of steroidal saponins have been received. Steroidal sapogenins, the aglycones of steroidal saponins, also have attracted much attention due to a vast range of pharmacological activities similar to steroidal saponins. In the past few years, structural modifications on the aglycones and sugar chains of steroidal saponins have been carried out and some achievements have been made. In this mini-review, the antitumor activity, action mechanisms, and structural modifications along with the structure-activity relationships of steroidal saponins and their derivatives are summarized.

Synthesis and biological evaluation of celastrol derivatives as potential anti-glioma agents by activating RIP1/RIP3/MLKL pathway to induce necroptosis

Celastrol, a quinone methide triterpenoid, possesses potential anti-glioma activity. However, its relatively low activity limit its application as an effective agent for glioma treatment. In search for effective anti-glioma agents, this work designed and synthesized two series of celastrol C-3 OH and C-20 COOH derivatives 4a-4o and 6a-6o containing 1, 2, 3-triazole moiety. Their anti-glioma activities against four human glioma cell lines (A172, LN229, U87, and U251) were then evaluated using MTT assay in vitro. Results showed that compound 6i (IC₅₀ = 0.94 μM) exhibited substantial antiproliferative activity against U251 cell line, that was 4.7-fold more potent than that of celastrol (IC₅₀ = 4.43 μM). In addition, compound 6i remarkably inhibited the colony formation and migration of U251 cells. Further transmission electron microscopy and mitochondrial depolarization assays in U251 cells indicated that the potent anti-glioma activity of 6i was attributed to necroptosis. Mechanism investigation revealed that compound 6i induced necroptosis mainly by activating the RIP1/RIP3/MLKL pathway. Additionally, compound 6i exerted acceptable BBB permeability in mice and inhibited U251 cell proliferation in an in vivo zebrafish xenograft model, obviously. In summary, compound 6i might be a promising lead compound for potent celastrol derivatives as anti-glioma agents.

Application of triazoles in the structural modification of natural products

Nature products have been extensively used in the discovery and development of new drugs, as the most important source of drugs. The triazole ring is one of main pharmacophore of the nitrogen-containing heterocycles. Thus, a new class of triazole-containing natural product conjugates has been synthesised. These compounds reportedly exert anticancer, anti-inflammatory, antimicrobial, antiparasitic, antiviral, antioxidant, anti-Alzheimer, and enzyme inhibitory effects. This review summarises the research progress of triazole-containing natural product derivatives involved in medicinal chemistry in the past six years. This review provides insights and perspectives that will help scientists in the fields of organic synthesis, medicinal chemistry, phytochemistry, and pharmacology.

Click Chemistry in Natural Product Modification

Click chemistry is perhaps the most powerful synthetic toolbox that can efficiently access the molecular diversity and unique functions of complex natural products up to now. It enables the ready synthesis of diverse sets of natural product derivatives either for the optimization of their drawbacks or for the construction of natural product-like drug screening libraries. This paper showcases the state-of-the-art development of click chemistry in natural product modification and summarizes the pharmacological activities of the active derivatives as well as the mechanism of action. The aim of this paper is to gain a deep understanding of the fruitful achievements and to provide perspectives, trends, and directions regarding further research in natural product medicinal chemistry.

Sarsasapogenin attenuates Alzheimer-like encephalopathy in diabetes

BACKGROUND

A crosstalk exists between diabetes and Alzheimer's disease (AD), and diabetic encephalopathy displays AD-like disorders. Sarsasapogenin (Sar) has strong anti-inflammatory efficacy, showing neuroprotection and memory-enhancement effects.

PURPOSE

This study aims to verify the ameliorative effects of Sar on diabetic encephalopathy in vivo and in vitro, and to clarify the mechanisms from attenuation of AD-like pathology.

METHODS

Streptozotocin-induced type 1 diabetic rats and high glucose-cultured SH-SY5Y cells were used in this study. After Sar treatment (20 and 60 mg/kg) for consecutive 9 weeks, Morris water maze and novel object recognition tasks were performed. Hematoxylin-eosin staining was used for examining loss of neurons in CA1 area and ki67 expression for reflecting neurogenesis in DG area of hippocampus. Aβ production pathway and tau phosphorylation kinase cascade were examined in these two models.

RESULTS

Sar improved learning and memory ability, loss of neurons and reduction of neurogenesis in the hippocampus of diabetic rats. Moreover, Sar suppressed Aβ overproduction due to up-regulation of BACE1 in protein and mRNA and tau hyperphosphorylation from inactivation of AKT/GSK-3β cascade in the hippocampus and cerebral cortex of diabetic rats and high glucose-cultured SH-SY5Y cells, and PPARγ antagonism abolished the effects of Sar on key molecules in the two pathways. Additionally, it was found that high glucose-stimulated Aβ overproduction was prior to tau hyperphosphorylation in neurons.

CONCLUSION

Sar alleviated diabetic encephalopathy, which was obtained through inhibitions of Aβ overproduction and tau hyperphosphorylation mediated by the activation of PPARγ signaling. Hence, Sar is a good candidate compound for AD-like disorders.

Recent Progress in the Drug Development for the Treatment of Alzheimer's Disease Especially on Inhibition of Amyloid-peptide Aggregation

As the world 's population is aging, Alzheimer's disease (AD) has become a big concern since AD has started affecting younger people and the population of AD patients is increasing worldwide. It has been revealed that the neuropathological hallmarks of AD are typically characterized by the presence of neurotoxic extracellular amyloid plaques in the brain, which are surrounded by tangles of neuronal fibers. However, the causes of AD have not been completely understood yet. Currently, there is no drug to effectively prevent AD or to completely reserve the symptoms in the patients. This article reviews the pathological features associated with AD, the recent progress in research on the drug development to treat AD, especially on the discovery of natural product derivatives to inhibit Aβ peptide aggregation as well as the design and synthesis of Aβ peptide aggregation inhibitors to treat AD.

Design and synthesis of novel diosgenin-triazole hybrids targeting inflammation as potential neuroprotective agents

Alzheimer's disease is a progressive neurodegenerative disease, and its incidence is expected to increase as the global population ages. Recent studies provide increasing evidence that inflammation plays a key role in the pathogenesis and progression of AD. Diosgenin, an active ingredient in Dioscorea nipponica Makino, is a promising bioactive lead compound in the treatment of Alzheimer's disease, which exhibited anti-inflammatory activity. To search for more efficient anti-Alzheimer agents, a series of novel diosgenin-triazolyl hybrids were designed, synthesized, and their neuroprotective effects against oxygen-glucose deprivation-induced neurotoxicity and LPS-induced NO production were evaluated. Most of these new hybrids displayed better activities than DIO. In particular, the promising compound L6 not only demonstrated an excellent neuroprotective effect but also showed the best anti-inflammatory activity. The structure-activity relationship study illustrated that the introduction of benzyl or phenyl triazole did improve the activity, and the introduction of benzyl triazole was better than that of phenyl triazole. The results we obtained showed that the diosgenin skeleton could be a promising structural template for the development of new anti-Alzheimer drug candidates, and compound L6 has the potential to be an important lead compound for further research.

Diosgenin Derivatives as Potential Antitumor Agents: Synthesis, Cytotoxicity, and Mechanism of Action

Thirty-two new diosgenin derivatives were designed, synthesized, and evaluated for their cytotoxic activities in three human cancer cell lines (A549, MCF-7, and HepG2) and normal human liver cells (L02) using an MTT assay in vitro. Most compounds, especially 8, 18, 26, and 30, were more potent when compared with diosgenin. The structure-activity relationship results suggested that the presence of a succinic acid or glutaric acid linker, a piperazinyl amide terminus, and lipophilic cations are all beneficial for promoting cytotoxic activity. Notably, compound 8 displayed excellent cytotoxic activity against HepG2 cells (IC₅₀ = 1.9 μM) and showed relatively low toxicity against L02 cells (IC₅₀ = 18.6 μM), showing some selectivity between normal and tumor cells. Studies on its cellular mechanism of action showed that compound 8 induces G0/G1 cell cycle arrest and apoptosis in HepG2 cells. Predictive studies indicated that p38α mitogen-activated protein kinase (MAPK) is the optimum target of 8 based on its 3D molecular similarity, and docking studies showed that compound 8 fits well into the active site of p38α-MAPK and forms relatively strong interactions with the surrounding amino acid residues. Accordingly, compound 8 may be used as a promising lead compound for the development of new antitumor agents.

Extracts from Chinese herbs with anti-amyloid and neuroprotective activities

Many Chinese herbs are well known for their neuroprotective and anti-oxidant properties. Extracts of Salvia miltiorrhiza and Anemarrhenae asphodeloides, tanshinone IIA (tanIIA), salvianolic acid B (Sal B) and sarsasapogenin (ML-1), were selected to study their dissociation potential towards Aβ₄₂ peptide fibrils and neuroprotective effect on cells. Moreover, derivatives of sarsasapogenin (ML-2, ML-3 and ML-4) have been prepared by the addition of modified carbamate moiety. TanIIA and Sal B have shown to possess a strong ability to dissociate Aβ₄₂ fibrils. The dissociation potential of ML-1 increased upon the introduction of carbamate moiety with N-heterocycles. In silico data revealed that derivatives ML-4 and Sal B interact with Aβ₄₂ regions responsible for fibril stabilization through hydrogen bonds. Contrary, tanIIA binds close to a central hydrophobic region, which may lead to destabilization of fibrils. Sarsasapogenin derivative ML-2 decreased nitride oxide production, and derivative ML-4 enhanced the growth of neurites. The reported data highlight the possibility of using active compounds to design novel treatment agents for Alzheimer's disease.

Anti-aging Klotho Protects SH-SY5Y Cells Against Amyloid β1-42 Neurotoxicity: Involvement of Wnt1/pCREB/Nrf2/HO-1 Signaling

Alzheimer's disease (AD) is considered a prevalent neurological disorder with a neurodegenerative nature in elderly people. Oxidative stress and neuroinflammation due to amyloid β (Aβ) peptides are strongly involved in AD pathogenesis. Klotho is an anti-aging protein with multiple protective effects that its deficiency is involved in development of age-related disorders. In this study, we investigated the beneficial effect of Klotho pretreatment at different concentrations of 0.5, 1, and 2 nM against Aβ1-42 toxicity at a concentration of 20 μM in human SH-SY5Y neuroblastoma cells. Our findings showed that Klotho could significantly and partially restore cell viability and decrease reactive oxygen species (known as ROS) and improve superoxide dismutase activity (SOD) in addition to reduction of caspase 3 activity and DNA fragmentation following Aβ1-42 challenge. In addition, exogenous Klotho also reduced inflammatory biomarkers consisting of nuclear factor-kB (NF-kB), interleukin-1β (IL-1β), and tumor necrosis factor-α (TNF-α) in Aβ-exposed cells. Besides, Klotho caused downregulation of Wnt1 level, upregulation of phosphorylated cyclic AMP response element binding (pCREB), and mRNA levels of nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase 1 (HO-1) with no significant alteration of epsilon isoform of protein kinase C (PKCε) after Aβ toxicity. In summary, Klotho could alleviate apoptosis, oxidative stress, and inflammation in human neuroblastoma cells after Aβ challenge and its beneficial effect is partially exerted through appropriate modulation of Wnt1/pCREB/Nrf2/HO-1 signaling.

Design, synthesis and biological evaluation of novel naturally-inspired multifunctional molecules for the management of Alzheimer's disease

In our overall goal to overcome the limitations associated with natural products for the management of Alzheimer's disease and to develop in-vivo active multifunctional cholinergic inhibitors, we embarked on the development of ferulic acid analogs. A systematic SAR study to improve upon the cholinesterase inhibition of ferulic acid with analogs that also had lower logP was carried out. Enzyme inhibition and kinetic studies identified compound 7a as a lead molecule with preferential acetylcholinesterase inhibition (AChE IC₅₀ = 5.74 ± 0.13 μM; BChE IC₅₀ = 14.05 ± 0.10 μM) compared to the parent molecule ferulic acid (% inhibition of AChE and BChE at 20 μM, 15.19 ± 0.59 and 19.73 ± 0.91, respectively). Molecular docking and dynamics studies revealed that 7a fits well into the active sites of AChE and BChE, forming stable and strong interactions with key residues Asp74, Trp286, and Tyr337 in AChE and with Tyr128, Trp231, Leu286, Ala328, Phe329, and Tyr341 in BChE. Compound 7a was found to be an efficacious antioxidant in a DPPH assay (IC₅₀ = 57.35 ± 0.27 μM), and it also was able to chelate iron. Data from atomic force microscopy images demonstrated that 7a was able to modulate aggregation of amyloid β_1-42. Upon oral administration, 7a exhibited promising in-vivo activity in the scopolamine-induced AD animal model and was able to improve spatial memory in cognitive deficit mice in the Y-maze model. Analog 7a could effectively reverse the increased levels of AChE and BChE in scopolamine-treated animals and exhibited potent ex-vivo antioxidant properties. These findings suggest that 7a can act as a lead molecule for the development of naturally-inspired multifunctional molecules for the management of Alzheimer's and other neurodegenerative disorders.

Critical evaluation of current Alzheimer's drug discovery (2018-19) & futuristic Alzheimer drug model approach

Alzheimer's disease (AD), a neurodegenerative disease responsible for death of millions of people worldwide is a progressive clinical disorder which causes neurons to degenerate and ultimately die. It is one of the common causes of dementia wherein a person's incapability to independently think, behave and decline in social skills can be quoted as major symptoms. However the early signs include the simple non-clinical symptoms such as forgetting recent events and conversations. Onset of these symptoms leads to worsened conditions wherein the AD patient suffers severe memory impairment and eventually becomes unable to work out everyday tasks. Even though there is no complete cure for AD, rigorous research has been going on to reduce the progress of AD. Currently, a very few clinical drugs are prevailing for AD treatment. So this is the need of hour to design, develop and discovery of novel anti-AD drugs. The main factors for the cause of AD according to scientific research reveals structural changes in brain proteins such as beta amyloid, tau proteins into plaques and tangles respectively. The abnormal proteins distort the neurons. Despite the high potencies of the synthesized molecules; they could not get on the clinical tests up to human usage. In this review article, the recent research carried out with respect to inhibition of AChE, BuChE, NO, BACE1, MAOs, Aβ, H3R, DAPK, CSF1R, 5-HT4R, PDE, σ₁R and GSK-3β is compiled and organized. The summary is focused mainly on cholinesterases, Aβ, BACE1 and MAOs classes of potential inhibitors. The review also covers structure activity relationship of most potent compounds of each class of inhibitors alongside redesign and remodeling of the most significant inhibitors in order to expect cutting edge inhibitory properties towards AD. Alongside the molecular docking studies of the some final compounds are discussed.

1,2,3-Triazole-containing hybrids as leads in medicinal chemistry: A recent overview

The 1,2,3-triazole ring is a major pharmacophore system among nitrogen-containing heterocycles. These five-membered heterocyclic motifs with three nitrogen heteroatoms can be prepared easily using 'click' chemistry with copper- or ruthenium-catalysed azide-alkyne cycloaddition reactions. Recently, the 'linker' property of 1,2,3-triazoles was demonstrated, and a novel class of 1,2,3-triazole-containing hybrids and conjugates was synthesised and evaluated as lead compounds for diverse biological targets. These lead compounds have been demonstrated as anticancer, antimicrobial, anti-tubercular, antiviral, antidiabetic, antimalarial, anti-leishmanial, and neuroprotective agents. The present review summarises advances in lead compounds of 1,2,3-triazole-containing hybrids, conjugates, and their related heterocycles in medicinal chemistry published in 2018. This review will be useful to scientists in research fields of organic synthesis, medicinal chemistry, phytochemistry, and pharmacology.