Design, synthesis, and biological evaluation of rutacecarpine derivatives as multitarget-directed ligands for the treatment of Alzheimer's disease

Design, synthesis, biological evaluation, and molecular modeling simulations of new phthalazine-1,4-dione derivatives as anti-Alzheimer's agents

The development of targeted phthalazine-1,4-dione acetylcholinesterase (AChE) inhibitors for treating Alzheimer's disease involved the synthesis of 32 compounds via a multistage process. Various analytical techniques confirmed the compounds' identities. Thirteen compounds were found to inhibit AChE by more than 50% without affecting butyrylcholinesterase (BChE). Among these, three compounds, 8m, 8n, and 8p, exhibited extraordinary activity similar to donepezil, a reference AChE inhibitor. During enzyme kinetic studies, compound 8n, displaying the highest AChE inhibitory activity, underwent evaluation at three concentrations (2 × IC50, IC50, and IC50/2). Lineweaver-Burk plots indicated mixed inhibition activity for compound 8n against AChE, suggesting a combination of competitive and noncompetitive characteristics. Additionally, effective derivatives 8m, 8n, and 8p exhibited high blood-brain barrier (BBB) permeability in in vitro parallel artificial membrane permeability assay tests. Molecular docking studies revealed that these compounds bind to the enzyme's active site residues in a position similar to donepezil. Molecular dynamic simulations confirmed the stability of the protein-ligand system, and the chemical reactivity characteristics of the compounds were investigated using density functional theory. The compounds' wide energy gaps suggest stability and therapeutic potential. This research represents a significant step toward finding a potential cure for Alzheimer's disease. However, further research and testing are required to determine the compounds' safety and efficacy. The unique structure of phthalazine derivatives makes them suitable for various biological activities, and these compounds show promise for developing effective drugs for treating Alzheimer's disease. Overall, the development of these targeted compounds is a crucial advancement in the search for an effective treatment for Alzheimer's disease.

Recent advances in the natural product analogues for the treatment of neurodegenerative diseases

Neurodegenerative diseases (NDs) represent a hallmark of numerous incapacitating and untreatable conditions, the incidence of which is escalating swiftly, exemplified by Alzheimer's disease and Parkinson's disease. There is an urgent necessity to create pharmaceuticals that exhibit high efficacy and minimal toxicity in order to address these debilitating diseases. The structural complexity and diversity of natural products confer upon them a broad spectrum of biological activities, thereby significantly contributing to the history of drug discovery. Nevertheless, natural products present challenges in drug discovery, including time-consuming separation processes, low content, low bioavailability, and other related issues. To address these challenges, numerous analogs of natural products have been synthesized. This methodology enables the rapid synthesis of analogs of natural products with the potential to serve as lead compounds for drug development, thereby paving the way for the discovery of novel pharmaceuticals. This paper provides a summary of 127 synthetic analogues featuring various natural product structures, including flavonoids, alkaloids, coumarins, phenylpropanoids, terpenoids, polyphenols, and amides. The compounds are categorized based on their efficacy in treating various diseases. Furthermore, this article delves into the structure-activity relationship (SAR) of certain analogues, offering a thorough point of reference for the systematic development of pharmaceuticals aimed at addressing neurodegenerative conditions.

Discovery of Novel Tryptanthrin Derivatives with Benzenesulfonamide Substituents as Multi-Target-Directed Ligands for the Treatment of Alzheimer's Disease

Based on the multi-target-directed ligands (MTDLs) approach, two series of tryptanthrin derivatives with benzenesulfonamide substituents were evaluated as multifunctional agents for the treatment of Alzheimer's disease (AD). In vitro biological assays indicated most of the derivatives had good cholinesterase inhibitory activity and neuroprotective properties. Among them, the target compound 4h was considered as a mixed reversible dual inhibitor of acetylcholinesterase (AChE, IC50 = 0.13 ± 0.04 μM) and butyrylcholinesterase (BuChE, IC50 = 6.11 ± 0.15 μM). And it could also potentially prevent the generation of amyloid plaques by inhibiting self-induced Aβ aggregation (63.16 ± 2.33%). Molecular docking studies were used to explore the interactions of AChE, BuChE, and Aβ. Furthermore, possessing significant anti-neuroinflammatory potency (NO, IL-1β, TNF-α; IC50 = 0.62 ± 0.07 μM, 1.78 ± 0.21 μM, 1.31 ± 0.28 μM, respectively) reduced ROS production, and chelated biometals were also found in compound 4h. Further studies showed that 4h had proper blood-brain barrier (BBB) permeability and suitable in vitro metabolic stability. In in vivo study, 4h effectively ameliorated the learning and memory impairment of the scopolamine-induced AD mice model. These findings suggested that 4h may be a promising compound for further development as a multifunctional agent for the treatment of AD.

Synthesis and properties of the kojic acid dimer and its potential for the treatment of Alzheimer's disease

The kojic acid dimer (KAD) is a metabolite derived from developing cottonseed when contaminated with aflatoxin. The KAD has been shown to exhibit bright greenish-yellow fluorescence, but little else is known about its biological activity. In this study, using kojic acid as a raw material, we developed a four-step synthetic route that achieved the gram-scale preparation of the KAD in approximately 25% total yield. The structure of the KAD was verified by single-crystal X-ray diffraction. The KAD showed good safety in a variety of cells and had a good protective effect in SH-SY5Y cells. At concentrations lower than 50 μM, the KAD was superior to vitamin C in ABTS⁺ free radical scavenging assay; the KAD resisted the production of reactive oxygen species induced by H₂O₂ as confirmed by fluorescence microscopy observation and flow cytometry analysis. Notably, the KAD could enhance the superoxide dismutase activity, which might be the mechanism of its antioxidant activity. The KAD also moderately inhibited the deposition of amyloid-β (Aβ) and selectively chelated Cu²⁺, Zn²⁺, Fe²⁺, Fe³⁺, and Al³⁺, which are related to the progress of Alzheimer's disease. Based on its good effects in terms of oxidative stress, neuroprotection, inhibition of Aβ deposition, and metal accumulation, the KAD shows potential for the multi-target treatment of Alzheimer's disease.

Novel quinoline-based derivatives: A new class of PDE4B inhibitors for adjuvant-induced arthritis

A total of 31 quinoline-based derivatives were designed and synthesized to develop novel anti-inflammatory drugs. After the toxicity of synthetic compounds to RAW264.7 cells were evaluated in vitro, their anti-inflammatory activity was assessed by inhibiting lipopolysaccharide (LPS)-induced NO production levels in the RAW264.7 cells. Among the derivatives, compound f4 had the best anti-inflammatory activity, which could reduce the production of pro-inflammatory cytokines NO, IL-1β, and TNF-α with corresponding IC₅₀ values of 20.40 ± 0.94, 18.98 ± 0.21 and 23.48 ± 0.46 μM. Western blot showed that f4 could inhibit the expression of LPS-induced inflammatory mediators iNOS and COX-2. Molecular docking showed that f4 could also enter the PDE4B receptor binding pocket, and the cellular thermal shift assay method indicated that the PDE4B protein bound to f4 had increased stability. Meanwhile, the inhibitory effect of this compound on the PDE4B enzyme (IC₅₀ = 0.94 ± 0.36 μM) was comparable to that of the positive drug rolipram (IC₅₀ = 1.04 ± 0.28 μM). Finally, in vivo studies showed that f4 could improve the degree of foot swelling and knee joint pathology in adjuvant-induced arthritic rats and decrease the levels of serum inflammatory factors TNF-α and IL-1β in a dose-dependent manner. Therefore, the development and design of quinoline-based derivatives for anti-inflammatory applications could be considered opportunities and challenges.

Advancements in the development of multi-target directed ligands for the treatment of Alzheimer's disease

Alzheimer's disease (AD) is a multifactorial irreversible neurological disorder which results in cognitive impairment, loss of cholinergic neurons in synapses of the basal forebrain and neuronal death. Exact pathology of the disease is not yet known however, many hypotheses have been proposed for its treatment. The available treatments including monotherapies and combination therapies are not able to combat the disease effectively because of its complex pathological mechanism. A multipotent drug for AD has the potential to bind or inhibit multiple targets responsible for the progression of the disease like aggregated Aβ, hyperphosphorylated tau proteins, cholinergic and adrenergic receptors, MAO enzymes, overactivated N-methyl-d-aspartate (NMDA), α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor etc. The traditional approach of one disease-one target-one drug has been rationalized to one drug-multi targets for the chronic diseases like AD and cancer. Thus, over the last decade research focus has been shifted towards the development of multi target directed ligands (MTDLs) which can simultaneously inhibit multiple targets and stop or slow the progression of the disease. The MTDLs can be more effective against AD and eliminate any possibility of drug-drug interactions. Many important active pharmacophore units have been fused, merged or incorporated into different scaffolds to synthesize new potent drugs. In the current article, we have described various hypothesis for AD and effectiveness of the MTDLs treatment strategy is discussed in detail. Different chemical scaffolds and their synthetic strategies have been described and important functionalities are identified in the chemical scaffold that have the potential to bind to the multiple targets. The important leads identified in this study with MTDL characteristics have the potential to be developed as drug candidates for the effective treatment of AD.

Discovery of novel paeonol-based derivatives against skin inflammation in vitro and in vivo

T-LAK-cell-originated protein kinase (TOPK), a novel member of the mitogen-activated protein kinase family, is considered an effective therapeutic target for skin inflammation. In this study, a series (A − D) of paeonol derivatives was designed and synthesised using a fragment growing approach, and their anti-inflammatory activities against lipopolysaccharide (LPS)-induced nitric oxide production in RAW264.7 cells were tested. Among them, compound B12 yielded the best results (IC₅₀ = 2.14 μM) with low toxicity (IC₅₀ > 50 µM). Preliminary mechanistic studies indicated that this compound could inhibit the TOPK-p38/JNK signalling pathway and phosphorylate downstream related proteins. A murine psoriasis-like skin inflammation model was used to determine its therapeutic effect.

Design, synthesis, and biological evaluation of novel (4-(1,2,4-oxadiazol-5-yl)phenyl)-2-aminoacetamide derivatives as multifunctional agents for the treatment of Alzheimer's disease

On the basis of our previous work, a novel series of (4-(1,2,4-oxadiazol-5-yl)phenyl)-2-aminoacetamide derivatives were synthesized and evaluated as multifunctional ligands for the treatment of Alzheimer's disease (AD). Biological evaluations indicated that the derivatives can be used as anti-AD drugs that have multifunctional properties, inhibit the activity of butyrylcholinesterase (BuChE), inhibit neuroinflammation, have neuroprotective properties, and inhibit the self-aggregation of Aβ. Compound f9 showed good potency in BuChE inhibition (IC₅₀: 1.28 ± 0.18 μM), anti-neuroinflammatory potency (NO, IL-1β, TNF-α; IC₅₀: 0.67 ± 0.14, 1.61 ± 0.21, 4.15 ± 0.44 μM, respectively), and inhibited of Aβ self-aggregation (51.91 ± 3.90%). Preliminary anti-inflammatory mechanism studies indicated that the representative compound f9 blocked the activation of the NF-κB signaling pathway. Moreover, f9 exhibited 1,1-Diphenyl-2-picrylhydrazyl (DPPH) radical scavenging effect, and an inhibitory effect on the production of intracellular reactive oxygen species (ROS). In the bi-directional transport assay, f9 displayed proper blood-brain barrier (BBB) permeability. In addition, the title compound improved memory and cognitive functions in a mouse model induced by scopolamine. Hence, the compound f9 can be considered as a promising lead compound for further investigation in the treatment of AD.

Structure-activity relationship, in vitro and in vivo evaluation of novel dienyl sulphonyl fluorides as selective BuChE inhibitors for the treatment of Alzheimer's disease

To discover novel scaffolds as leads against dementia, a series of δ-aryl-1,3-dienesulfonyl fluorides with α-halo, α-aryl and α-alkynyl were assayed for ChE inhibitory activity, in which compound A10 was identified as a selective BuChE inhibitor (IC50 = 0.021 μM for eqBChE, 3.62 μM for hBuChE). SAR of BuChE inhibition showed: (i) o- > m- > p-; -OCH3 > -CH3 > -Cl (-Br) for δ-aryl; (ii) α-Br > α-Cl, α-I. Compound A10 exhibited neuroprotective, BBB penetration, mixed competitive inhibitory effect on BuChE (Ki = 29 nM), and benign neural and hepatic safety. Treatment with A10 could almost entirely recover the Aβ1-42-induced cognitive dysfunction to the normal level, and the assessment of total amount of Aβ1-42 confirmed its anti-amyloidogenic profile. Therefore, the potential BuChE inhibitor A10 is a promising effective lead for the treatment of AD.

Identification of novel acetylcholinesterase inhibitors through 3D-QSAR, molecular docking, and molecular dynamics simulation targeting Alzheimer's disease

Acetylcholinesterase (AChE) is a potential target for the development of small molecules as inhibitors for the therapy of Alzheimer's disease (AD). To design highly active acetylcholinesterase inhibitors, a three-dimensional quantitative structure-activity relationship (3D-QSAR) approach was performed on a series of N-benzylpyrrolidine derivatives previously evaluated for acetylcholinesterase inhibitory activity. The developed two models, CoMFA and CoMSIA, were statistically validated, and good predictability was achieved for both models. The information generated from 3D-QSAR contour maps may provide a better understanding of the structural features required for acetylcholinesterase inhibition and help to design new potential anti-acetylcholinesterase molecules. Consequently, six novel acetylcholinesterase inhibitors were designed, among which compound A1 with the highest predicted activity was subjected to detailed molecular docking and compared to the most active compound. Extra-precision molecular dynamics (MD) simulation of 50 ns and binding free energy calculations using MM-GBSA were performed for the selected compounds to validate the stability. These results may afford important structural insights needed to identify novel acetylcholinesterase inhibitors and other promising strategies in drug discovery.

Synthesis and evaluation of the anti-inflammatory activity of novel 8-quinolinesulfonamide derivatives as TLR4/MD-2 inhibitors with efficacy in adjuvant-induced arthritis

In this study, a series of 8-quinolinesulfonamidederivatives was synthesized, and their anti-inflammatory activity was evaluated. Among them, compound 3l was found to be the best anti-inflammatory agent, with IC50 values of 2.61 ± 0.39, 9.74 ± 0.85, and 12.71 ± 1.34 μM against NO, TNF-α and IL-1β production respectively. And 3l could significantly prevent lipopolysaccharide (LPS)-induced expression of inflammatory mediators (iNOS and COX-2). Molecule docking results showed that 3l could bind to the LPS binding site of toll-like receptor 4 (TLR4)/MD-2, and 3l was then identified as TLR4/MD-2 inhibitor by co-immunoprecipitation (co-IP) and cellular thermal shift assay (CTESA). Preliminary mechanism studies indicated that 3l could prevent TLR4 from being activated by disrupting TLR4/MD-2 heterodimerization and TLR4 homodimerization, thereby blocking the activation of the NF-κB/MAPK signaling pathway. Furthermore, observation of rat foot swelling, joint pathology and serum inflammatory cytokine levels proved that compound 3l had a significant therapeutic effect on adjuvant-induced arthritis (AIA) in rats in vivo. These results indicated that compound 3l is a potential anti-inflammatory agent, from which more effective anti-inflammatory drugs could be developed.

Novel cannabidiol-carbamate hybrids as selective BuChE inhibitors: Docking-based fragment reassembly for the development of potential therapeutic agents against Alzheimer's disease

Cannabidiol (CBD) and rivastigmine have been launched as drugs for treating dementia and cholinesterases (ChEs) are ideal drug targets. This study focused on developing novel ChE inhibitors as drug leads against dementia through molecular modeling and fragment reassembly approaches. A potent carbamate fragment binding to active site gorge of BuChE was found via a docking-based structural splicing approach, thus, 17 novel compounds were designed by structural reassembly. Compound C16 was identified as a highly selective potent BuChE inhibitor (IC₅₀ = 5.3 nM, SI > 4000), superior to CBD (IC₅₀ = 0.67 μM). C16 possessed BBB penetrating ability, benign safety, neuroprotection, antioxidant and pseudo-irreversible BuChE inhibition (K_d = 13 nM, k₂ = 0.26 min^-1), showing good drug-like properties. In vivo studies confirmed that C16 significantly ameliorated the scopolamine-induced cognition impairment, almost entirely recovered the Aβ_1-42 (icv)-impaired cognitive function to the normal level, showed better behavioral performance than donepezil and good anti-amyloidogenic effect. Hence, the potential BuChE inhibitor C16 can be developed as a promising disease-modifying treatment of AD.

Visible-Light-Mediated Synthesis of Rutaecarpine Alkaloids through C–N Cross-Coupling Reaction

A visible-light-initiated cross-dehydrogenative-coupling amination is described, featuring metal- and photocatalyst-free, at room temperature, and using air as an oxidant. The reaction provides a facile approach for the synthesis of rutaecarpine and its derivatives. The substrates with electron-withdrawing groups give higher yields than those with electron-donating groups, but the substituent position has a negligible influence on the yield. Using binaphthyl-diyl hydrogen phosphate and dibenzyl phosphate as catalysts both deliver satisfying yields. This straightforward light-driven strategy might be applicable to the synthesis of quinazolinone derivatives.

Discovery of 7-O-1, 2, 3-triazole hesperetin derivatives as multi-target-directed ligands against Alzheimer's disease

The development of multi-target-directed ligands (MTDLs) may improve complex central nervous system diseases such as Alzheimer's disease (AD). Here, a series of 7-O-1, 2, 3-triazole hesperetin derivatives was evaluated for their inhibition of cholinesterase, anti-neuroinflammatory, and neuroprotective activity. Among the hesperetin derivatives, compound a8 (7-O-((1-(3-chlorobenzyl)-1H-1,2,3-triazol-4-yl)methyl)hesperetin) possessed excellent anti-butyrylcholinesterase activity (IC50 = 3.08 ± 0.29 μM) and exhibited good anti-neuroinflammatory activity (IC50 = 2.91 ± 0.47 μM) against NO production through remarkably blocking the NF-κB signaling pathway and inhibiting the phosphorylation of P65. In addition, a8 showed a remarkable neuroprotective effect and lacked neurotoxicity up to 50 μM concentration. Furthermore, possessing significant self-mediated Aβ1-42 aggregation inhibitory activity, chelated biometals and reduced ROS production were found in compound a8. In the bi-directional transport assay, a8 exhibited a blood-brain barrier penetrating ability. In this study, the Morris water maze task showed that compound a8 significantly improved the learning and memory impairment of the scopolamine-induced AD mice model. Results highlighted the potential of compound a8 to be a potential MTDL for the development of anti-AD agents.

Novel pyridine-containing sultones: Structure-activity relationship and biological evaluation as selective AChE inhibitors for the treatment of Alzheimer's disease

Novel pyridine-containing sultones were synthesized and evaluated for their cholinesterase (ChE) inhibitory activity. Most of compounds showed selective acetylcholinesterase (AChE) inhibitory activity. The structure-activity relationship (SAR) showed: (i) the fused pyridine-containing sultones increase AChE inhibition, series B>series A; (ii) for series A, the effect of the 4-substituent on AChE activity, p->m- or o-; (iii) for series B, a halophenyl group increase activity. Compound B4 (4-(4-chlorophenyl)-2,2-dioxide-3,4,5,6-tetrahydro-1,2-oxathiino[5,6-h]quinoline) was identified as a selective AChE inhibitor (IC₅₀ =8.93 μM), and molecular docking studies revealed a good fit into TcAChE via hydrogen interactions between the δ-pyridylsultone scaffold with Asp72, Ser122, Phe288, Phe290 and Trp84. Compound B4 showed reversible and non-competitive (K_i =7.67 μM) AChE inhibition, nontoxicity and neuroprotective activity. In vivo studies confirmed that compound B4 could ameliorate the cognitive performance of scopolamine-treated C57BL/6 J mice, suggesting a significant benefit of AChE inhibition for a disease-modifying treatment of AD.

Synthesis and activity of miconazole derivatives as dual BChE/IDO1 inhibitors for the treatment of Alzheimer's disease

Background: Alzheimer's disease is a multifactorial neurological disorder seen in elderly people. Loss of cholinergic transmission and unbalanced tryptophan metabolism kynurenine pathway have been demonstrated in neuropsychiatric diseases. Methods & results: Among the two series of synthesized compounds, compounds 5c and 5h were identified as effective dual BChE/IDO1 inhibitors, with well-balanced micromolar activity. Compounds 5c and 5h exhibited promising ability to ameliorate behavioral impairment by Morris water maze. The safety of miconazole analogs was also validated by PC12 and SH-SY5Y cell lines. Conclusion: These results highlight the ability of 5c and 5h to treat Alzheimer's disease.

3-B-RUT, a derivative of RUT, protected against alcohol-induced liver injury by attenuating inflammation and oxidative stress

Alcoholic liver disease (ALD) is the most common chronic liver disease worldwide. Currently, there is no definitive treatment for alcohol-induced liver injury (ALI). Inflammatory response and oxidative stress play a crucial role in ALI. Cyclooxygenase 2 (COX-2) can be induced by inflammation and it has been reported that the enhanced expression of COX-2 in alcoholic liver injury. Rutaecarpine (RUT) was extracted from evodia rutaecarpa. RUT has a wide range of pharmacological activities. In order to increase its anti-inflammatory activity, our group introduced sulfonyl group to synthesized the 3-[2-(trifluoromethoxy)benzenesulfonamide]-rutaecarpine (3-B-RUT). In this study, we explored the protective effect of 3-B-RUT on alcoholic liver injury in vivo and in vitro and preliminarily explore its mechanism. Mice ALI model was established according to the chronic-plus-binge ethanol model. Results showed that 3-B-RUT (20 μg/kg) attenuated alcohol-induced liver injury and suppressed liver inflammation and oxidative stress, and the effect was comparable to RUT (20 mg/kg). In vitro results are consistent with in vivo results. Mechanistically, the 3-B-RUT might suppress inflammatory response and oxidative stress by regulating activation of NF-κB/COX-2 pathway. In summary, 3-B-RUT, a derivative of RUT, may be a promising clinical candidate for ALI treatment.

Quinuclidine-Based Carbamates as Potential CNS Active Compounds

The treatment of central nervous system (CNS) diseases related to the decrease of neurotransmitter acetylcholine in neurons is based on compounds that prevent or disrupt the action of acetylcholinesterase and butyrylcholinesterase. A series of thirteen quinuclidine carbamates were designed using quinuclidine as the structural base and a carbamate group to ensure the covalent binding to the cholinesterase, which were synthesized and tested as potential human acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitors. The synthesized compounds differed in the substituents on the amino and carbamoyl parts of the molecule. All of the prepared carbamates displayed a time-dependent inhibition with overall inhibition rate constants in the 103 M-1 min-1 range. None of the compounds showed pronounced selectivity for any of the cholinesterases. The in silico determined ability of compounds to cross the blood-brain barrier (BBB) revealed that six compounds should be able to pass the BBB by passive transport. In addition, the compounds did not show toxicity toward cells that represented the main models of individual organs. By machine learning, the most optimal regression models for the prediction of bioactivity were established and validated. Models for AChE and BChE described 89 and 90% of the total variations among the data, respectively. These models facilitated the prediction and design of new and more potent inhibitors. Altogether, our study confirmed that quinuclidinium carbamates are promising candidates for further development as CNS-active drugs, particularly for Alzheimer's disease treatment.

β-Carboline as a Privileged Scaffold for Multitarget Strategies in Alzheimer's Disease Therapy

The natural β-carboline alkaloids display similarities with neurotransmitters that can be favorably exploited to design bioactive and bioavailable drugs for Alzheimer's disease (AD) therapy. Several AD targets are currently and intensively being investigated, divided in different hypotheses: mainly the cholinergic, the amyloid β (Aβ), and the Tau hypotheses. To date, only symptomatic treatments are available involving acetylcholinesterase and NMDA inhibitors. On the basis of plethoric single-target structure-activity relationship studies, the β-carboline scaffold was identified as a powerful tool for fostering activity and molecular interactions with a wide range of AD-related targets. This knowledge can undoubtedly be used to design multitarget-directed ligands, a highly relevant strategy preferred in the context of multifactorial pathology with intricate etiology such as AD. In this review, we first individually discuss the AD targets of the β-carbolines, and then we focus on the multitarget strategies dedicated to the deliberate design of new efficient scaffolds.

Design and synthesis of 3-(4-pyridyl)-5-(4-sulfamido-phenyl)-1,2,4-oxadiazole derivatives as novel GSK-3β inhibitors and evaluation of their potential as multifunctional anti-Alzheimer agents

Pleiotropic intervention has prominent advantages for complex pathomechanisms, such as Alzheimer's disease (AD). In this study, a series of novel 3-(4-pyridyl)-5-(4- sulfamido-phenyl)-1,2,4-oxadiazole derivatives were designed and synthesized following the multitarget-directed ligand-based strategy. All compounds were evaluated for glycogen synthase kinase 3β (GSK-3β) inhibition and antineuroinflammatory and neuroprotective activities. Given that abnormal glucose metabolism plays an important role in AD occurrence and development, the effects of all compounds on glucose consumption in HepG2 cells was evaluated. Compounds 5e and 10b showed good dual potency in GSK-3β inhibition (IC50: 5e = 1.52 μM, 10b = 0.19 μM) and antineuroinflammatory potency (IC50: 5e = 0.47 ± 0.64 μM, 10b = 6.94 ± 2.33 μM). The effect of compound 10b on glucose consumption was higher than that of positive drug metformin. These compounds exerted a certain neuroprotective effect. Compound 10b dramatically reduced Aβ-induced Tau hyperphosphorylation, thus inhibiting GSK-3β at the cellular level. Notably, compounds 5e and 10b exhibited good inhibitory effects on the formation of intracellular reactive oxygen species (ROS). Moreover, these compounds displayed proper blood-brain barrier permeability and lacked neurotoxicity up to 50 μM concentration. Finally, in vivo experiments revealed that compound 10b improved cognitive impairment in scopolamine-induced mouse models. Results indicated that compound 10b deserves further study as a multifunctional lead compound.

Biological evaluation of 7-O-amide hesperetin derivatives as multitarget-directed ligands for the treatment of Alzheimer's disease

A series of 7-O-amide hesperetin derivatives were subjected to multi-target biological evaluation of anti-Alzheimer's disease. Most of the compounds showed good in vitro inhibitory activity against cholinesterase, of which compound 7c (7-O-(4-(morpholinoethyl)-acetamide) hesperetin) was the most effective anti-eqBuChE derivative (IC₅₀ = 0.28 ± 0.05 μM) and exerted neuroprotective effects. Further biological evaluation found that compounds 4d, 4e and 7c showed strong antioxidant, anti-Aβ self-aggregation and anti-neuroinflammatory activities. Compound 7c could inhibit the expression of iNOS and COX-2 proteins and prevent LPS-induced inflammatory response in BV2 cells. In addition, compound 7c could chelate biometal ions such as Cu²⁺ and Zn²⁺. In the vivo study, the MWM test confirmed that compound 7c could improve the cognitive impairment caused by scopolamine. In summary, the above studies have shown that the optimized compound 7c has great development potential as MTDL for the treatment of AD.

Identification of novel CDK 9 inhibitors based on virtual screening, molecular dynamics simulation, and biological evaluation

AIMS

Cyclin-dependent kinase 9 (CDK9) is a member of the CDK subfamily and plays a major role in the regulation of transcriptional elongation. It has attracted widespread attention as a therapeutic target for cancer. Here, we aimed to explore novel CDK 9 inhibitors by using a hybrid virtual screening strategy.

MAIN METHODS

A hybrid virtual screening strategy was constructed with computer-aided drug design (CADD). First, compounds were filtered in accordance with Lipinski's rule of five and adsorption, distribution, metabolism, excretion, and toxicity (ADMET) properties. Second, a 3D-QSAR pharmacophore model was built and used as a 3D query to screen the obtained hit compounds. Third, the hit compounds were subjected to molecular docking studies. Fourth, molecular dynamics (MD) simulations were performed on CDK9 in complex with the final hits to examine the structural stability. Finally, CDK9 kinase biochemical assay was performed to identify the biological activity of the hit compounds.

KEY FINDINGS

Seven hit compounds were screened out. These hit compounds showed drug-like properties in accordance with Lipinski's rule of five and ADMET. Complexes involving the six hit compounds bound to CDK9 exhibited good structural stability in the MD simulation. Furthermore, these six hit compounds had strong inhibitory activity against CDK9 kinase. In particular, hit 3 showed the most promising activity with the percentage of 71%.

SIGNIFICANCE

The six hit compounds may be promising novel CDK9 inhibitors, and the hybrid virtual screening strategy designed in this study provides an important reference for the design and synthesis of novel CDK9 inhibitors.

Rutaecarpine derivative Cpd-6c alleviates acute kidney injury by targeting PDE4B, a key enzyme mediating inflammation in cisplatin nephropathy

Acute kidney injury (AKI), characterized by a rapid decline in renal function, is triggered by an acute inflammatory response that leads to kidney damage. An effective treatment for AKI is lacking. Using in vitro and in vivo AKI models, our laboratory has identified a series of anti-inflammatory molecules and their derivatives. In the current study, we identified the protective role of rutaecarpine (Ru) on renal tubules. We obtained a series of 3-aromatic sulphonamide-substituted Ru derivatives exhibiting enhanced renoprotective and anti-inflammatory function. We identified Compound-6c(Cpd-6c) as having the best activity and examined its protective effect against cisplatin nephropathy both in vivo and in vitro in cisplatin-stimulated tubular epithelial cells (TECs). Our results showed that Cpd-6c restored renal function more effectively than Ru, as evidenced by reduced blood urea nitrogen and serum creatinine levels in mice. Cpd-6c alleviated tubular injury, as shown by PAS staining and molecular analysis of kidney injury molecule-1 (KIM-1), with both prevention and treatment protocols in cisplatin-treated mice. Moreover, Cpd-6c decreased kidney inflammation, oxidative stress and programmed cell death. These results have also been confirmed in cisplatin-treated TECs. Using web-prediction algorithms, molecular docking, and cellular thermal shift assay (CETSA), we identified phosphodiesterase 4B (PDE4B) as a Cpd-6c target. In addition, we firstly found that PDE4B was up-regulated significantly in the serum of AKI patients. After identifying the function of PDE4B in cisplatin-treated tubular epithelial cells by siRNA transfection or PDE4 inhibitor rolipram, we showed that Cpd-6c treatment did not protect against cisplatin-induced injury in PDE4B knockdown TECs, thus indicating that Cpd-6c exerts its renoprotective and anti-oxidative effects via the PDE4B-dependent pathway. Collectively, Cpd-6c might serve as a potential therapeutic agent for AKI and PDE4B may be highly involved in the initiation and progression of AKI.

Multitarget Therapeutic Strategies for Alzheimer's Disease: Review on Emerging Target Combinations

Neurodegenerative diseases represent nowadays one of the major health problems. Despite the efforts made to unveil the mechanism leading to neurodegeneration, it is still not entirely clear what triggers this phenomenon and what allows its progression. Nevertheless, it is accepted that neurodegeneration is a consequence of several detrimental processes, such as protein aggregation, oxidative stress, and neuroinflammation, finally resulting in the loss of neuronal functions. Starting from these evidences, there has been a wide search for novel agents able to address more than a single event at the same time, the so-called multitarget-directed ligands (MTDLs). These compounds originated from the combination of different pharmacophoric elements which endowed them with the ability to interfere with different enzymatic and/or receptor systems, or to exert neuroprotective effects by modulating proteins and metal homeostasis. MTDLs have been the focus of the latest strategies to discover a new treatment for Alzheimer's disease (AD), which is considered the most common form of dementia characterized by neurodegeneration and cognitive dysfunctions. This review is aimed at collecting the latest and most interesting target combinations for the treatment of AD, with a detailed discussion on new agents with favorable in vitro properties and on optimized structures that have already been assessed in vivo in animal models of dementia.