N-Benzyl Benzamide Derivatives as Selective Sub-Nanomolar Butyrylcholinesterase Inhibitors for Possible Treatment in Advanced Alzheimer's Disease

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.

New insights into butyrylcholinesterase: Pharmaceutical applications, selective inhibitors and multitarget-directed ligands

Butyrylcholinesterase (BChE), also known as pseudocholinesterase and serum cholinesterase, is an isoenzyme of acetylcholinesterase (AChE). It mediates the degradation of acetylcholine, especially under pathological conditions. Proverbial pharmacological applications of BChE, its mutants and modulators consist of combating Alzheimer's disease (AD), influencing multiple sclerosis (MS), addressing cocaine addiction, detoxifying organophosphorus poisoning and reflecting the progression or prognosis of some diseases. Of interest, recent reports have shed light on the relationship between BChE and lipid metabolism. It has also been proved that BChE is going to increase abnormally as a compensator for AChE in the middle and late stages of AD, and BChE inhibitors can alleviate cognitive disorders and positively influence some pathological features in AD model animals, foreboding favorable prospects and potential applications. Herein, the selective BChE inhibitors and BChE-related multitarget-directed ligands published in the last three years were briefly summarized, along with the currently known pharmacological applications of BChE, aiming to grasp the latest research directions. Thereinto, some emerging strategies for designing BChE inhibitors are intriguing, and the modulators based on target combination of histone deacetylase and BChE against AD is unprecedented. Furthermore, the involvement of BChE in the hydrolysis of ghrelin, the inhibition of low-density lipoprotein (LDL) uptake, and the down-regulation of LDL receptor (LDLR) expression suggests its potential to influence lipid metabolism disorders. This compelling prospect likely stimulates further exploration in this promising research direction.

Advances in dual-targeting inhibitors of HDAC6 for cancer treatment

Histone Deacetylase 6 (HDAC6) is an essential regulator of histone acetylation processes, exerting influence on a multitude of cellular functions such as cell motility, endocytosis, autophagy, apoptosis, and protein trafficking through its deacetylation activity. The significant implications of HDAC6 in diseases such as cancer, neurodegenerative disorders, and immune disorders have motivated extensive investigation into the development of specific inhibitors targeting this enzyme for therapeutic purposes. Single targeting drugs carry the risk of inducing drug resistance, thus prompting exploration of dual targeting therapy which offers the potential to impact multiple signaling pathways simultaneously, thereby lowering the likelihood of resistance development. While pharmacological studies have exhibited promise in combined therapy involving HDAC6, challenges related to potential drug interactions exist. In response to these challenges, researchers are investigating HDAC6 hybrid molecules which enable the concomitant targeting of HDAC6 and other key proteins, thus enhancing treatment efficacy while mitigating side effects and reducing the risk of resistance compared to traditional combination therapies. The published design strategies for dual targeting inhibitors of HDAC6 are summarized and discussed in this review. This will provide some valuable insights into more novel HDAC6 dual targeting inhibitors to meet the urgent need for innovative therapies in oncology and other related fields.

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.

Butyrylcholinesterase-Activated Near-Infrared Fluorogenic Probe for In Vivo Theranostics of Alzheimer's Disease

Butyrylcholinesterase (BChE) is a promising biomarker and effective therapeutic target for Alzheimer's disease (AD). Herein, we designed a BChE-activated near-infrared (NIR) probe, DTNP, which could be activated by BChE and inhibit its enzymatic activity. DTNP is composed of a cyclopropane moiety as the recognition unit, a NIR fluorophore hemicyanine as the NIR reporter, and a BChE inhibitor as the therapeutic unit. DTNP specifically binds BChE with high sensitivity and exhibits strong "turn-on" NIR fluorescence as well as nerve cell protection. In vivo imaging shows DTNP has favorable blood-brain barrier permeability and long-term tracking ability with preliminary competence in AD diagnosis. DTNP can significantly inhibit BChE activity, promote the release of ACh, and rescue learning deficits and cognitive impairment. Therefore, DTNP, the first reported and partially validated theranostic probe for the detection of BChE in AD, may provide a foundation and inspiration for imaging and therapy in AD.

Direct Synthesis of α- and β-2'-Deoxynucleosides with Stereodirecting Phosphine Oxide via Remote Participation

2'-Deoxynucleosides and analogues play a vital role in drug development, but their preparation remains a significant challenge. Previous studies have focused on β-2'-deoxynucleosides with the natural β-configuration. In fact, their isomeric α-2'-deoxynucleosides also exhibit diverse bioactivities and even better metabolic stability. Herein, we report that both α- and β-2'-deoxynucleosides can be prepared with high yields and stereoselectivity using a remote directing diphenylphosphinoyl (DPP) group. It is particularly efficient to prepare α-2'-deoxynucleosides with an easily accessible 3,5-di-ODPP donor. Instead of acting as a H-bond acceptor on a 2-(diphenylphosphinoyl)acetyl (DPPA) group in our previous studies for syn-facial O-glycosylation, the phosphine oxide moiety here acts as a remote participating group to enable highly antifacial N-glycosylation. This proposed remote participation mechanism is supported by our first characterization of an important 1,5-briged P-heterobicyclic intermediate via variable-temperature NMR spectroscopy. Interestingly, antiproliferative assays led to a α-2'-deoxynucleoside with IC50 values in the low micromole range against central nervous system tumor cell lines SH-SY5Y and LN229, whereas its β-anomer exhibited no inhibition at 100 μM. Furthermore, the DPP group significantly enhanced the antitumor activities by 10 times.

Discovery, Structure-Based Modification, In Vitro, In Vivo, and In Silico Exploration of m-Sulfamoyl Benzoamide Derivatives as Selective Butyrylcholinesterase Inhibitors for Treating Alzheimer's Disease

For the potential therapy of Alzheimer's disease (AD), butyrylcholinesterase (BChE) has gradually gained worldwide interest in the progression of AD. This study used a pharmacophore-based virtual screening (VS) approach to identify Z32439948 as a new BChE inhibitor. Aiding by molecular docking and molecular dynamics, essential binding information was disclosed. Specifically, a subpocket was found and structure-guided design of a series of novel compounds was conducted. Derivatives were evaluated in vitro for cholinesterase inhibition and physicochemical properties (BBB, log P, and solubility). The investigation involved docking, molecular dynamics, enzyme kinetics, and surface plasmon resonance as well. The study highlighted compounds 27a (hBChE IC50 = 0.078 ± 0.03 μM) and (R)-37a (hBChE IC50 = 0.005 ± 0.001 μM) as the top-ranked BChE inhibitors. These compounds showed anti-inflammatory activity and no apparent cytotoxicity against the human neuroblastoma (SH-SY5Y) and mouse microglia (BV2) cell lines. The most active compounds exhibited the ability to improve cognition in both scopolamine- and Aβ1-42 peptide-induced cognitive deficit models. They can be promising lead compounds with potential implications for treating the late stage of AD.

Calcium channel blockers' contribution to overcoming Current drug discovery challenges in Alzheimer's disease

INTRODUCTION

Alzheimer's disease (AD) is a progressive, irreversible, and multifactorial brain disorder that gradually and insidiously destroys individual's memory, thinking, and other cognitive abilities.

AREAS COVERED

In this perspective, the authors examine the complex and multifactorial nature of Alzheimer's disease and believe that the best approach to develop new drugs is the MTDL strategy, which obviously faces several challenges. These challenges include identifying the key combination of targets and their suitability for coordinated actions, as well as developing an acceptable pharmacokinetic and toxicological profile to deliver a drug candidate.

EXPERT OPINION

Since calcium plays a crucial role in the pathology of AD, a polypharmacological approach with calcium channel blockers reinforced by activities targeting other factors involved in AD is a serious option in our opinion. This is exemplified by a phase III clinical trial using a drug combination approach with Losartan, Amlodipine (a calcium channel blocker), and Atorvastatin, as well as several MTDL-based calcium channel blockade approaches with a promising in vitro and in vivo profile.

Palladium-catalyzed synthesis and anti-AD biological activity evaluation of N-aryl-debenzeyldonepezil analogues

A series of novel N-aryl-debenzeyldonepezil derivatives (1-26) were designed and synthesized as cholinesterase inhibitors by the modification of anti-Alzheimer's disease drug donepezil, using Palladium catalyzed Buchwald-Hartwig cross-coupling reaction as a key chemical synthesis strategy. In vitro cholinesterase inhibition studies demonstrated that the majority of synthesized compounds exhibited high selective inhibition of AChE. Among them, analogue 13 possessing a quinoline functional group showed the most potent AChE inhibition effect and significant neuroprotective effect against H2O2-induced injury in SH-SY5Y cells. Furthermore, Compound 13 did not show significant cytotoxicity on SH-SY5Y. These results suggest that 13 is a potential multifunctional active molecule for treating Alzheimer's disease.

New Benzamides as Multi-Targeted Compounds: A Study on Synthesis, AChE and BACE1 Inhibitory Activity and Molecular Docking

The synthesis of eleven new and previously undescribed benzamides was designed. These compounds were specifically projected as potential inhibitors of the enzymes acetylcholinesterase (AChE) and β-secretase (BACE1). N,N'-(1,4-phenylene)bis(3-methoxybenzamide) was most active against AChE, with an inhibitory concentration of AChE IC50 = 0.056 µM, while the IC50 for donepezil was 0.046 µM. This compound was also the most active against the BACE1 enzyme. The IC50 value was 9.01 µM compared to that for quercetin, with IC50 = 4.89 µM. Quantitative results identified this derivative to be the most promising. Molecular modeling was performed to elucidate the potential mechanism of action of this compound. Dynamic simulations showed that new ligands only had a limited stabilizing effect on AChE, but all clearly reduced the flexibility of the enzyme. It can, therefore, be concluded that a possible mechanism of inhibition increases the stiffness and decreases the flexibility of the enzyme, which obviously impedes its proper function. An analysis of the H-bonding patterns suggests a different mechanism (from other ligands) when interacting the most active derivative with the enzyme.

Design, Synthesis, and Proof of Concept of Balanced Dual Inhibitors of Butyrylcholinesterase (BChE) and Histone Deacetylase 6 (HDAC6) for the Treatment of Alzheimer's Disease

Concomitant inhibition of butyrylcholinesterase (BChE) and histone deacetylase 6 (HDAC6) is supposed to be effective in the treatment of Alzheimer's disease (AD). Inspired by our previous efforts in designing BChE inhibitors, herein, selective BChE and HDAC6 dual inhibitors were successfully identified through the fusion of the core pharmacophoric moiety of BChE and HDAC6 inhibitors. After the structure-activity relationship (SAR) studies, two compounds (24g and 29a) were confirmed to have superior inhibitory activity against BChE (the IC50 against hBChE are 4.0 and 1.8 nM, respectively) and HDAC6 (the IC50 against HDAC6 are 8.9 and 71.0 nM, respectively). These two compounds showed prominently neuroprotective effects in vitro, potent reactive oxygen species (ROS) scavenging effects, and effective metal ion (Fe2+ and Cu2+) chelation. In addition, they exhibited pronounced inhibition of phosphorylated tau and a moderate immunomodulatory effect, with a lack of neurotoxicity at the cellular level. In vivo studies showed that both 24g and 29a ameliorated the cognitive impairment in an Aβ1-42-induced mouse model at a low dosage (2.5 mg/kg). Our data demonstrated that BChE/HDAC6 dual inhibitors could establish the basis for a potential new symptomatic and disease-modifying strategy to treat AD.

Sulfur-fluoride exchange (SuFEx)-enabled lead discovery of AChE inhibitors by fragment linking strategies

SuFEx click chemistry has been a method for the rapid synthesis of functional molecules with desirable properties. Here, we demonstrated a workflow that allows for in situ synthesis of sulfonamide inhibitors based on SuFEx reaction for high-throughput testing of their cholinesterase activity. According to fragment-based drug discovery (FBDD), sulfonyl fluorides [R-SO₂F] with moderate activity were identified as fragment hits, rapidly diversified into 102 analogs in SuFEx reactions, and the sulfonamides were directly screened to yield drug-like inhibitors with 70-fold higher potency (IC₅₀ = 94 nM). Moreover, the improved molecule J8-A34 can ameliorate cognitive function in Aβ_1-42-induced mouse model. Since this SuFEx linkage reaction succeeds on picomole scale for direct screening, this methodology can accelerate the development of robust biological probes and drug candidates.

Dual-Acting Small Molecules: Subtype-Selective Cannabinoid Receptor 2 Agonist/Butyrylcholinesterase Inhibitor Hybrids Show Neuroprotection in an Alzheimer's Disease Mouse Model

We present the synthesis and characterization of merged human butyrylcholinesterase (hBChE) inhibitor/cannabinoid receptor 2 (hCB₂R) ligands for the treatment of neurodegeneration. In total, 15 benzimidazole carbamates were synthesized and tested for their inhibition of human cholinesterases, also with regard to their pseudoirreversible binding mode and affinity toward both cannabinoid receptors in radioligand binding studies. After evaluation in a calcium mobilization assay as well as a β-arrestin 2 (βarr2) recruitment assay, two compounds with balanced activities on both targets were tested for their immunomodulatory effect on microglia activation and regarding their pharmacokinetic properties and blood-brain barrier penetration. Compound 15d, containing a dimethyl carbamate motif, was further evaluated in vivo, showing prevention of Aβ_25-35-induced learning impairments in a pharmacological mouse model of Alzheimer's disease for both short- and long-term memory responses. Additional combination studies proved a synergic effect of BChE inhibition and CB₂R activation in vivo.

Highly selective butyrylcholinesterase inhibitors related to Amaryllidaceae alkaloids - Design, synthesis, and biological evaluation

Butyrylcholinesterase (BChE) is one of the most frequently implicated enzymes in the advanced stage of Alzheimer's disease (AD). As part of our endeavors to develop new drug candidates for AD, we have focused on natural template structures, namely the Amaryllidaceae alkaloids carltonine A and B endowed with high BChE selectivity. Herein, we report the design, synthesis, and in vitro evaluation of 57 novel highly selective human BChE (hBChE) inhibitors. Most synthesized compounds showed hBChE inhibition potency ranging from micromolar to low nanomolar scale. Compounds that revealed BChE inhibition below 100 nM were selected for detailed biological investigation. The CNS-targeted profile of the presented compounds was confirmed theoretically by calculating the BBB score algorithm, these data were corroborated by determining the permeability in vitro using PAMPA-assay for the most active derivatives. The study highlighted compounds 87 (hBChE IC₅₀ = 3.8 ± 0.2 nM) and 88 (hBChE IC₅₀ = 5.7 ± 1.5 nM) as the top-ranked BChE inhibitors. Compounds revealed negligible cytotoxicity for the human neuroblastoma (SH-SY5Y) and hepatocellular carcinoma (HepG2) cell lines compared to BChE inhibitory potential. A crystallographic study was performed to inspect the binding mode of compound 87, revealing essential interactions between 87 and hBChE active site. In addition, multidimensional QSAR analyses were applied to determine the relationship between chemical structures and biological activity in a dataset of designed agents. Compound 87 is a promising lead compound with potential implications for treating the late stages of AD.

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

We synthesized a series of novel pyromeconic acid-styrene hybrid compounds and measured their activities in inhibiting Aβ_1-42 self-aggregation and promoting disaggregation, and their anti-inflammatory and antioxidant properties. The most potent compound, compound 30, had IC₅₀ values of 11.15 μM and 6.87 μM for inhibition of fibril aggregation and promotion of fibril disaggregation, respectively. Because of its redox metal chelating property, 30 also inhibited Cu²⁺-induced Aβ_1-42 fibril aggregation and promoted fibril disaggregation with IC₅₀ of 3.69 μM and 3.35 μM, respectively. Molecular docking demonstrated that 30 interacted with key amino acids of Aβ_1-42, and the reliability of the complex was confirmed by molecular dynamics. In addition, 30 displayed excellent antioxidative activity (oxygen radical absorbance capacity = 2.65 Trolox equivalents) and moderate anti-inflammatory activity and neuroprotection in cell culture assays. Compound 30 was safe in acute toxicity test in mice, and it exhibited favorable pharmacokinetic properties, particularly, accumulation in the hippocampus (maximum ratio of hippocampus to plasma = 7.12). Compound 30 alleviated cognitive deficits in scopolamine-induced amnesia mice; this property may have been attributed to reducing neuroinflammation by inhibiting ionized calcium binding adapter molecule 1 and glial fibrillary acidic protein expression and reducing oxidative stress by activating the Nrf2/HO-1 signaling pathway. In view of its many properties, we envision that 30 is a promising lead for the treatment of Alzheimer's disease.

Multicomponent reactions as a privileged tool for multitarget-directed ligand strategies in Alzheimer's disease therapy

Among neurodegenerative pathologies affecting the older population, Alzheimer's disease is the most common type of dementia and leads to neurocognitive and behavioral disorders. It is a complex and progressive age-related multifactorial disease characterized by a series of highly interconnected pathophysiological processes. Within the last decade, the multitarget-directed ligand strategy has emerged as a viable approach to developing complex molecules that exhibit several pharmacophores which can target the different enzymes and receptors involved in the pathogenesis of the disease. Herein, we focus on using multicomponent reactions such as Hantzsch, Biginelli and Ugi to develop these biologically active multitopic ligands.