Anti-cholinesterase hybrids as multi-target-directed ligands against Alzheimer’s disease (1998–2018)

Biological activities and phytochemical characterization of Sideritis germanicopolitana subsp. viridis and S. libanotica subsp. linearis extracts and extract-loaded nanoparticles

Introduction

The current study focuses on evaluating the biological activity and analysis of phytochemical content of extracts and extract-loaded nanoparticles from Sideritis germanicopolitana subsp. viridis (endemic, SGV) and S. libanotica subsp. linearis (SLL).

Methods

Antioxidant activities of extracts and nanoparticles were investigated by DPPH, FRAP and CUPRAC methods. Enzyme inhibition potentials of extracts and nanoparticles were evaluated by Ellman and indophenol methods. Phytochemical contents were analyzed by HPLC-DAD. Plant extracts were encapsulated by the ionic gelation method which was modified in our laboratory using the green chemistry approach.

Results and Discussion

It was found that the 70% ethanol extracts of SGV and SLL exhibited the highest antioxidant activity in terms of DPPH, FRAP and CUPRAC compared to other extracts. The findings showed that both 70% ethanol extract-loaded nanoparticles obtained from SGV and SLL showed lower DPPH radical scavenging, iron (III) reducing and copper (II) reducing activities compared to crude extracts. It was determined that the 70% extracts of SGV and SLL exhibited a higher potential to inhibit the enzyme urease than other extracts. The anti-urease activity of the nanoparticle loaded with SLL 70% ethanol extract was found to be greater than that of the nanoparticle made with SGV 70% ethanol extract. Furthermore, an analysis of the acetylcholinesterase enzyme inhibition capacity of various extracts from both plants revealed that the 70% ethanol extracts of each plant species had a greater potential for enzyme inhibition than the other extracts. The anticholinesterase activity of the nanoparticle loaded with SLL 70% extract was found to be higher than that of the nanoparticle loaded with SGV 70% ethanol extract. In this study the phenolic metabolites were examined, luteolin (27.44 μg/mg extract) and p-coumaric acid (20.03 μg/mg extract) were found at the highest concentration in the SGV plant while rosmarinic acid (8.70 μg/mg extract), caffeic acid (6.46 μg/mg extract) and p-coumaric acid (4.42 μg/mg extract) were found at the highest concentration in the SLL plant. However, the data demonstrated that the nanoparticles had lesser biological activity potential than crude extracts.

Conclusion

The substantial biological activities of the nanoparticles developed as a result of this work showed that these formulations are suitable for use as antioxidant, anti-urease and anticholinesterase medicines in the future due to the benefits of using nanoparticles in the therapeutics such as the controlled release of the active agents and the diminished side effects.

Recent advancements in the therapeutic approaches for Alzheimer's disease treatment: current and future perspective

Alzheimer's disease (AD) is a complex, incurable neurological condition characterized by cognitive decline, cholinergic neuron reduction, and neuronal loss. Its exact pathology remains uncertain, but multiple treatment hypotheses have emerged. The current treatments, single or combined, alleviate only symptoms and struggle to manage AD due to its multifaceted pathology. The developmental drugs target pivotal disease factors involved in the envisaged hypotheses and include targets such as amyloid aggregation, hyperphosphorylated tau proteins, and receptors like cholinergic, adrenergic, etc. Present-day research focuses on multi-target directed ligands (MTDLs), which inhibit multiple factors simultaneously, helping slow the disease's progression. This review attempts to collate the recent information related to proposed hypotheses for AD etiology. It systematically organizes the advances in various therapeutic options for AD, with a particular emphasis on clinical candidates. Also, it is expected to help medicinal chemists design novel AD treatments based on available information, which could be helpful to AD patients.

Structure-based inhibition of acetylcholinesterase and butyrylcholinesterase with 2-Aryl-6-carboxamide benzoxazole derivatives: synthesis, enzymatic assay, and in silico studies

An important research topic is the discovery of multifunctional compounds targeting different disease-causing components. This research aimed to design and synthesize a series of 2-aryl-6-carboxamide benzoxazole derivatives that inhibit cholinesterases on both the peripheral anionic and catalytic anionic sides. Compounds (7-48) were prepared from 4-amino-3-hydroxybenzoic acid in three steps. The Ellman test, molecular docking with Maestro, and molecular dynamics simulation studies with Desmond were done (Schrodinger, 12.8.117). Compound 36, the most potent compound among the 42 new compounds synthesized, had an inhibitory concentration of IC50 12.62 nM for AChE and IC50 25.45 nM for BChE (whereas donepezil was 69.3 nM and 63.0 nM, respectively). Additionally, compound 36 had docking values ​​of - 7.29 kcal/mol for AChE and - 6.71 kcal/mol for BChE (whereas donepezil was - 6.49 kcal/mol and - 5.057 kcal/mol, respectively). Furthermore, molecular dynamics simulations revealed that compound 36 is stable in the active gorges of both AChE (average RMSD: 1.98 Å) and BChE (average RMSD: 2.2 Å) (donepezil had average RMSD: 1.65 Å and 2.7 Å, respectively). The results show that compound 36 is a potent, selective, mixed-type dual inhibitor of both acetylcholinesterase and butyrylcholinesterase. It does this by binding to both the catalytically active and peripheral anionic sites of cholinesterases at the same time. These findings show that target compounds may be useful for establishing the structural basis for new anti-Alzheimer agents.

Conjugates of amiridine and salicylic derivatives as promising multifunctional CNS agents for potential treatment of Alzheimer's disease

New conjugates of amiridine and salicylic derivatives (salicylamide, salicylimine, and salicylamine) with different lengths of alkylene spacers were designed, synthesized, and evaluated as potential multifunctional central nervous system therapeutic agents for Alzheimer's disease (AD). Conjugates demonstrated high acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibition (IC50: AChE, 0.265-4.24 μM; BChE, 0.01-0.64 μM) but poor activity against off-target carboxylesterase (CES). Specifically, conjugates with a (CH2)8 spacer showed the highest AChE and BChE inhibition: 3-16 times more effective than amiridine. Salicylamides 7b and 7c had the maximum BChE/AChE selectivity ratios: 193 and 138, respectively. Conjugates were mixed-type reversible inhibitors of both cholinesterases and displaced propidium from the AChE peripheral anionic site (PAS) at the level of donepezil. All conjugates inhibited Aβ42 self-aggregation in the thioflavin test; inhibition increased with spacer elongation, being greatest for (CH2)8. The results agreed with molecular docking to AChE, BChE, and Aβ42. Conjugates exhibited high 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS)•+-scavenging activity comparable to the standard antioxidant Trolox, and they showed the ability to bind Cu2+, Fe2+, and Zn2+. Conjugates had favorable predicted intestinal absorption and blood-brain barrier permeability. Altogether, the results indicate that the new conjugates possess potential for further development as multifunctional anti-AD drug candidates.

NMR Metabolite Profiling and Antioxidant Properties of Spartan, Jewels, Misty, and Camelia Blueberries

The health-promoting properties of blueberries are widely recognized and are mainly attributed to anthocyanins. However, fruit's chemical composition includes also other components and strongly depends on varieties and climatic conditions. Here, 1H NMR metabolite profiling and biological activity of four blueberry cultivars (Spartan, Jewels, Misty, Camelia) grown in Central Italy over two years were reported. Untargeted and targeted NMR analyses allowed the quantification of sugars, organic acids, amino acids, anthocyanins, lipids, and other compounds. Spectrophotometric assays evaluated total phenolic and flavonoid content, antioxidant activity, and enzyme inhibitory activity toward cholinesterase, α-amylase, α-glucosidase, and tyrosinase. Statistical analysis showed a correlation between chemical composition and biological activity, revealing markers specific to blueberry cultivars (quinic acid, quercitrin, myo-inositol, myrtillin, and petunidin-3-O-glucoside). Almost all antioxidant assays were correlated with the chlorogenic acid levels. A strong effect of harvesting on chemical composition and biological activities was observed, with Misty cultivar having the highest antioxidant activity.

Influence of extraction solvents on the chemical constituents and biological activities of Astragalus aduncus from Turkey flora: In vitro and in silico insights

The n-hexane, ethyl acetate, ethanol, ethanol/water (70% ethanol), and water extracts of Astragalus aduncus aerial parts were investigated for their antioxidant potential, enzyme inhibition activity (anti-acetylcholinesterase [AChE], anti-butyrylcholinesterase [BChE], antityrosinase, antiamylase, and antiglucosidase) and antiproliferative effect (against colon adenocarcinoma cell line [HT-29], gastric cancer cell line [HGC-27], prostate carcinoma cell line [DU-145], breast adenocarcinoma cell line [MDA-MB-231], and cervix adenocarcinoma cell line [HeLa]). In addition, the phytochemical profile of the extracts was evaluated using validated spectrophotometric and high-pressure liquid chromatography-electrospray ionization/tandem mass spectroscopy methods. Generally, the 70% ethanol extract demonstrated the strongest antioxidant properties, and it was the richest source of total phenolic constituents. Our findings indicated that the ethyl acetate extract was the most potent BChE inhibitor (11.44 mg galantamine equivalents [GALAE]/g) followed by the ethanol extract (8.51 mg GALAE/g), while the ethanol extract was the most promising AChE inhibitor (3.42 mg GALAE/g) followed by the ethanol/water extract (3.17 mg GALAE/g). Excellent tyrosinase inhibitory activity (66.25 mg kojic acid equivalent/g) was observed in ethanol/water extracts of the aerial part of A. aduncus. Тhese results showed that the most cytotoxic effects were exhibited by the ethyl acetate extract against HGC-27 cells (IC50: 36.76 µg/mL), the ethanol extract against HT-29 cells (IC50: 30.79 µg/mL), and the water extract against DU-145 cells (IC50: 37.01 µg/mL). A strong correlation was observed between the highest total flavonoid content and the highest content of individual compounds in the ethanol extract, including rutin, hyperoside, isoquercitrin, delphinidin-3,5-diglucoside (delphinidin-3,5-O-diglucoside), and kaempferol-3-glucoside (kaempferol-3-O-glucoside). In the present study, the A. aduncus plant was considered a new source of antioxidants, enzyme inhibitors, and anticancer agents and could be used as a future health-benefit natural product.

Comparison of Anticancer, Antioxidant, Enzyme Inhibitory Effects and Phytochemical Contents Between Edible Lettuce (Lactuca sativa) and a New Wild Species (Lactuca anatolica)

In this study, the bioactive components, enzyme inhibitory, antioxidant and anticancer potentials of edible (L. sativa) and a new species (L. anatolica) of Lactuca were evaluated and compared. The quantitative analyzes of the bioactive components of L. sativa (LS) and L. anatolica (LA) were analyzed quantitatively by GC-MS and Orbitrab HPLC-HRMS. Antioxidant, enzyme inhibitory and anticancer properties were analyzed by various assays. In general, LA exhibited more stronger antioxidant properties compared to LS. The extracts showed similar inhibitory effects on these enzymes. It was determined that LS was dominant in terms of linoleic acid (23.71 %), while LA contained a high level of α-linolenic acid (31.70 %). LA and LS inhibited the viability of A549 and MCF-7 cells in a dose-dependent manner. IC50 values for LA, LS and cisplatin were determined as 120.3, 197.5, 4.3 μg/mL in A549 cell line and 286.2, 472.8, 7.2 μg/mL in MCF-7 cell line, respectively. It was revealed that LA and LS treatment at 50 μg/mL concentrations in A549 cells completely suppressed the colony forming capacity, and treatment with IC50 doses inhibited cell migration, and triggered apoptosis by regulating caspase-3, cPARP, p53 and p21. The findings of this study suggested that these species have significant pharmacological potential.

Synthesis and biological evaluation of Halogen-Substituted novel α-Ketoamides as potential protein aggregation modulators in Alzheimer's disease

The escalating prevalence of Alzheimer's disease (AD) has prompted extensive research into potential therapeutic interventions, with a specific focus on molecular targets such as amyloid beta (Aβ) and tau protein aggregation. In this study, a series of α-ketoamide derivatives was synthesized from β,γ-unsaturated α-keto thioesters, achieving high purity and good yield. Thioflavin T based Aβ aggregation assay identified four promising compounds (BD19, BD23, BD24, and BD27) that demonstrated significant inhibitory effects on Aβ aggregation. BD23, selected for its better solubility (0.045 ± 0.0012 mg/ml), was further subjected to in vitro Parallel Artificial Membrane Permeability Assay to determine the Blood-Brain-Barrier permeability and emerged as BBB permeable with permeability rate (Pe) of 10.66 ± 8.11 × 10-6 cm/s. In addition to its Aβ inhibitory properties, BD23 exhibited significant inhibition of heparin-induced tau aggregation and demonstrated non-toxicity in SHSY5Y cell lines. Subsequent in vivo assays were conducted, administering compound BD23 to an Aβ induced mouse model of AD at various doses (1, 2, & 5 mg/kg). The results revealed a noteworthy enhancement in cognitive functions, particularly when BD23 was administered at a dosage of 5 mg/kg, comparable to the effects observed with the standard dose of Donepezil (DNP). In silico investigations, including molecular docking, molecular dynamics simulations, and Density Functional Theory calculations provided insights into BD23's interactions with the targets and electronic properties. These analyses contribute to the understanding of the therapeutic potential of the lead compounds BD23 which further pave the way for further exploration of its therapeutic potential in the context of AD.

Early- and Late-Onset Alzheimer's Disease: Two Sides of the Same Coin?

Early-onset Alzheimer's disease (EOAD), defined as Alzheimer's disease onset before 65 years of age, has been significantly less studied than the "classic" late-onset form (LOAD), although EOAD often presents with a more aggressive disease course, caused by variants in the APP, PSEN1, and PSEN2 genes. EOAD has significant differences from LOAD, including encompassing diverse phenotypic manifestations, increased genetic predisposition, and variations in neuropathological burden and distribution. Phenotypically, EOAD can be manifested with non-amnestic variants, sparing the hippocampi with increased tau burden. The aim of this article is to review the different genetic bases, risk factors, pathological mechanisms, and diagnostic approaches between EOAD and LOAD and to suggest steps to further our understanding. The comprehension of the monogenic form of the disease can provide valuable insights that may serve as a roadmap for understanding the common form of the disease.

Structure-Guided Design, Synthesis, and Biological Evaluation of Peripheral Anionic Site Selective and Brain Permeable Novel Oxadiazole-Piperazine Conjugates against Alzheimer's Disease with Antioxidant Potential

Alzheimer's disease (AD) is a multifactorial and emerging neurological disorder, which has invoked researchers to develop multitargeted ligands. Herein, hybrid conjugates of 5-phenyl-1,3,4-oxadiazole and piperazines were rationally designed, synthesized, and pharmacologically evaluated against hAChE, hBChE, and hBACE-1 enzymes for the management of AD. Among the series, compound 5AD comprising pyridyl substitution at terminal nitrogen of piperazine contemplated as a paramount lead compound (hAChE, IC50 = 0.103 ± 0.0172 μM, hBChE, IC50 ≥ 10 μM, and hBACE-1, IC50 = 1.342 ± 0.078 μM). Compound 5AD showed mixed-type enzyme inhibition in enzyme kinetic studies against the hAChE enzyme. In addition, compound 5AD revealed a significant displacement of propidium iodide from the peripheral anionic site (PAS) of hAChE and excellent blood-brain barrier (BBB) permeability in a parallel artificial membrane permeation assay (PAMPA). Besides, 5AD also exhibited anti-Aβ aggregation activity in self- and AChE-induced thioflavin T assay. Further, compound 5AD has shown significant improvement in learning and memory (p < 0.001) against the in vivo scopolamine-induced cognitive dysfunction mice model. The ex vivo study implied that after treatment with compound 5AD, there was a decrease in AChE and malonaldehyde (MDA) levels with an increase in catalase (CAT, oxidative biomarkers) in the hippocampal brain homogenate. Hence, compound 5AD could be regarded as a lead compound and further be explored in the treatment of AD.

Diet-gut microbiome interaction and ferulic acid bioavailability: implications on neurodegenerative disorders

PURPOSE OF THE REVIEW

Ferulic acid (FA), which occurs naturally as the feruloylated sugar ester in grains, fruits, and vegetables, is critical for combating oxidative stress and alleviating neurodegenerative diseases resulting from free radical-generated protein aggregates in brain cells. However, FA cannot be absorbed in conjugated form. Therefore, strategies to improve the bioavailability of FA are gaining more importance. Ferulic acid esterases (FAE) of the gut microbiota are critical enzymes that facilitate FA release from feruloylated sugar ester conjugates and influence systemic health. This review provides insight into a nutrition-based approach to preventing neurodegenerative disorders such as Alzheimer's and Parkinson's by altering the diversity of FAE-producing gut microbiota.

RECENT FINDINGS

The human gut is a niche for a highly dense microbial population. Nutrient components and the quality of food shape the gut microbiota. Microbiota-diet-host interaction primarily involves an array of enzymes that hydrolyse complex polysaccharides and release covalently attached moieties, thereby increasing their bio-accessibility. Moreover, genes encoding polysaccharide degrading enzymes are substrate inducible, giving selective microorganisms a competitive advantage in scavenging nutrients. Nutraceutical therapy using specific food components holds promise as a prophylactic agent and as an adjunctive treatment strategy in neurotherapeutics, as it results in upregulation of polysaccharide utilisation loci containing fae genes in the gut microbiota, thereby increasing the release of FA and other antioxidant molecules and combat neurodegenerative processes.

Triple in silico targeting of IMPDH enzyme and RNA-dependent RNA polymerase of both SARS-CoV-2 and Rhizopus oryzae

Aim: Mucormycosis has been associated with SARS-CoV-2 infections during the last year. The aim of this study was to triple-hit viral and fungal RNA-dependent RNA polymerases (RdRps) and human inosine monophosphate dehydrogenase (IMPDH). Materials & methods: Molecular docking and molecular dynamics simulation were used to test nucleotide inhibitors (NIs) against the RdRps of SARS-CoV-2 and Rhizopus oryzae RdRp. These same inhibitors targeted IMPDH. Results: Four NIs revealed a comparable binding affinity to the two drugs, remdesivir and sofosbuvir. Binding energies were calculated using the most abundant conformations of the RdRps after 100-ns molecular dynamics simulation. Conclusion: We suggest the triple-inhibition potential of four NIs against pathogenic RdRps and IMPDH, which is worth experimental validation.

Novel benzothiazole derivatives as multitargeted-directed ligands for the treatment of Alzheimer's disease

Neurodegenerative diseases such as Alzheimer's disease (AD) are multifactorial with several different pathologic mechanisms. Therefore, it is assumed that multitargeted-directed ligands (MTDLs) which interact with different biological targets relevant to the diseases, might offer an improved therapeutic alternative than using the traditional "one-target, one-molecule" approach. Herein, we describe new benzothiazole-based derivatives as a privileged scaffold for histamine H₃ receptor ligands (H₃R). The most affine compound, the 3-(azepan-1-yl)propyloxy-linked benzothiazole derivative 4b, displayed a K_i value of 0.012 μM. The multitargeting potential of these H₃R ligands towards AChE, BuChE and MAO-B enzymes was evaluated to yield compound 3s (pyrrolidin-1-yl-(6-((5-(pyrrolidin-1-yl)pentyl)oxy)benzo[d]thiazol-2-yl)methanone) as the most promising MTDL with a K_i value of 0.036 μM at H₃R and IC₅₀ values of 6.7 µM, 2.35 µM, and 1.6 µM towards AChE, BuChE, and MAO-B, respectively. These findings suggest that compound 3s can be a lead structure for developing new multi-targeting anti-AD agents.

Some morpholine tethered novel aurones: Design, synthesis, biological, kinetic and molecular docking studies

Enzymes are the biological macromolecules that have emerged as an important drug target as their upregulation/imbalance leads to various pathological conditions, such as inflammation, parasitic infection, Alzheimer's, cancer, and many others. Here, we designed and synthesized some morpholine tethered novel aurones and evaluated them as potential inhibitors for CTSB, α-amylase, lipase and activator for trypsin. All the newly synthesized compounds were fully characterized by various spectroscopic techniques (1H NMR, 13C NMR, HRMS) and the Z-configuration to them was assigned based on single crystal XRD data and 1H NMR chemical shift values. Further, the hybrids were evaluated for their intracellular (cathepsin B) and extracellular (trypsin, lipase, amylase) enzyme inhibition potencies. The in-vitro inhibition screening against cathepsin B revealed that most of the synthesized compounds are good competitive inhibitors (% inhibition = 22.91-75.04), with 6q (% inhibition = 75.04) and 6r (% inhibition = 71.13) as the eminent inhibitors of the series. At the same time, they exhibited weak to moderate inhibition towards amylase (% inhibition = 7.22-22.48) and lipase (% inhibition = 16.29-54.83). A significant trypsin activation (% activation = 107.42-196.47) was observed even at the micromolar concentration of the compounds. Furthermore, the drug-modeling studies showed a good correlation between the in-vitro experimental results and the calculated binding affinity of the screened compounds with all the tested enzymes. These findings are expected to provide a new lead in drug development for different pathological disorders wherever these enzymes are involved.

A Workflow Combining Machine Learning with Molecular Simulations Uncovers Potential Dual-Target Inhibitors against BTK and JAK3

The drug development process suffers from low success rates and requires expensive and time-consuming procedures. The traditional one drug-one target paradigm is often inadequate to treat multifactorial diseases. Multitarget drugs may potentially address problems such as adverse reactions to drugs. With the aim to discover a multitarget potential inhibitor for B-cell lymphoma treatment, herein, we developed a general pipeline combining machine learning, the interpretable model SHapley Additive exPlanation (SHAP), and molecular dynamics simulations to predict active compounds and fragments. Bruton's tyrosine kinase (BTK) and Janus kinase 3 (JAK3) are popular synergistic targets for B-cell lymphoma. We used this pipeline approach to identify prospective potential dual inhibitors from a natural product database and screened three candidate inhibitors with acceptable drug absorption, distribution, metabolism, excretion, and toxicity (ADMET) properties. Ultimately, the compound CNP0266747 with specialized binding conformations that exhibited potential binding free energy against BTK and JAK3 was selected as the optimum choice. Furthermore, we also identified key residues and fingerprint features of this dual-target inhibitor of BTK and JAK3.

Antioxidant and Enzyme Inhibitory Activities of Rhoifolin Flavonoid: In Vitro and in Silico Studies

Rhoifolin (apigenin-7-O-β-neohesperidoside) belongs to the class of flavonoids and was reported to exhibit anti-inflammatory, cytotoxic, antidiabetic, hepatoprotective, and cardioprotective activities. The current study presents the in-vitro evaluation of the antioxidative effects of rhoifolin by many assays, namely DPPH, CUPRAC, ABTS, phosphomolybdenum, and FRAP. Enzyme inhibitory potential was also evaluated for acetylcholinesterase (AChE), butyrylcholinesterase (BChE), tyrosinase, amylase, and glucosidase enzymes. While results revealed weak antioxidant activities for rhoifolin, the compound demonstrated some promising enzyme inhibitory effects against BChE (4.03 mg GALAE/g) and tyrosinase (7.44 mg KAE/g) but was not active on AChE. Regarding anti-diabetic enzymes, the compound was active on amylase but did not show any inhibition effect on glucosidase. In-silico molecular docking study was performed for rhoifolin on the active site of NADPH oxidase, BChE, and amylase enzymes to verify the observed enzyme inhibitory effect. Good binding affinities were observed for rhoifolin on all the docked enzymes, revealing numerous hydrogen bonds, carbon-hydrogen, van der Waals interactions. This is the first study to evaluate the enzyme inhibition potential of rhoifolin. We concluded that the increase in the degree of glycosylation might decrease the antioxidant abilities of flavonoids and that rhoifolin had moderate enzyme inhibition abilities to be investigated in future studies.

Modified Tacrine Derivatives as Multitarget-Directed Ligands for the Treatment of Alzheimer's Disease: Synthesis, Biological Evaluation, and Molecular Modeling Study

To develop multitarget-directed ligands (MTDLs) as potential treatments for Alzheimer's disease (AD) and to shed light on the effect of the chromene group in designing these ligands, 35 new tacrine-chromene derivatives were designed, synthesized, and biologically evaluated. Compounds 5c and 5d exhibited the most desirable multiple functions for AD; they were strong hAChE inhibitors with IC₅₀ values of 0.44 and 0.25 μM, respectively. Besides, their potent BuChE inhibitory activity was 10- and 5-fold more active than rivastigmine with IC₅₀ = 0.08 and 0.14 μM, respectively. Moreover, they could bind to the peripheral anionic site (PAS), influencing Aβ aggregation and decreasing Aβ-related neurodegeneration, especially compound 5d, which was 8 times more effective than curcumin with IC₅₀ = 0.74 μM and 76% inhibition at 10 μM. Compounds 5c and 5d showed strong BACE-1 inhibition at the submicromolar level with IC₅₀ = 0.38 and 0.44 μM, respectively, which almost doubled the activity of curcumin. They also showed single-digit micromolar inhibitory activity against MAO-B with IC₅₀ = 5.15 and 2.42 μM, respectively. They also had antioxidant activities and showed satisfactory metal-chelating properties toward Fe⁺², Zn⁺², and Cu⁺², inhibiting oxidative stress in AD brains. Furthermore, compounds 5c and 5d showed acceptable relative safety upon normal cells SH-SY5Y and HepG2. It was shown that 5c and 5d were blood-brain barrier (BBB) penetrants by online prediction. Taken together, these multifunctional properties highlight that compounds 5c and 5d can serve as promising candidates for the further development of multifunctional drugs against AD.

Advances in the discovery of heterocyclic-based drugs against Alzheimer's disease

INTRODUCTION

Alzheimer's disease is a multifactorial neurodegenerative disorder characterized by beta-amyloid accumulation and tau protein hyperphosphorylation. The disease involves interconnected mechanisms, which can be clustered into two target-packs based on the affected proteins. Pack-1 focuses on beta-amyloid accumulation, oxidative stress, and metal homeostasis dysfunction, and Pack-2 involves tau protein, calcium homeostasis, and neuroinflammation. Against this background heterocyclic system, there is a powerful source of pharmacophores to develop effective small drugs to treat multifactorial diseases like Alzheimer's.

AREAS COVERED

This review highlights the most promising heterocyclic systems as potential hit candidates with multi-target capacity for the development of new drugs targeting Alzheimer's disease. The selection of these heterocyclic systems was based on two crucial factors: their synthetic versatility and their well-documented biological properties of therapeutic potential in neurodegenerative diseases.

EXPERT OPINION

The synthesis of small drugs against Alzheimer's disease requires a multifactorial approach that targets the key pathological proteins. In this context, the utilization of heterocyclic systems, with well-established synthetic processes and facile functionalization, becomes a crucial element in the design phases. Furthermore, the selection of hit heterocyclic should be guided by a full understanding of their biological activities. Thus, the identification of promising heterocyclic scaffolds with known biological effects increases the potential to develop effective molecules against Alzheimer's disease.

N-Methyl Costaricine and Costaricine, Two Potent Butyrylcholinesterase Inhibitors from Alseodaphne pendulifolia Gamb

Studies have been conducted over the last decade to identify secondary metabolites from plants, in particular those from the class of alkaloids, for the development of new anti-Alzheimer's disease (AD) drugs. The genus Alseodaphne, comprising a wide range of alkaloids, is a promising source for the discovery of new cholinesterase inhibitors, the first-line treatment for AD. With regard to this, a phytochemical investigation of the dichloromethane extract of the bark of A. pendulifolia Gamb. was conducted. Repeated column chromatography and preparative thin-layer chromatography led to the isolation of a new bisbenzylisoquinoline alkaloid, N-methyl costaricine (1), together with costaricine (2), hernagine (3), N-methyl hernagine (4), corydine (5), and oxohernagine (6). Their structures were elucidated by the 1D- and 2D-NMR techniques and LCMS-IT-TOF analysis. Compounds 1 and 2 were more-potent BChE inhibitors than galantamine with IC₅₀ values of 3.51 ± 0.80 µM and 2.90 ± 0.56 µM, respectively. The Lineweaver-Burk plots of compounds 1 and 2 indicated they were mixed-mode inhibitors. Compounds 1 and 2 have the potential to be employed as lead compounds for the development of new drugs or medicinal supplements to treat AD.

Thiadiazole – A promising structure in design and development of anti-Alzheimer agents

The design and development of effective multitargeted agents in treating Alzheimer disease (AD) has always been a hot topic in the field of drug discovery. Since AD is a multifactorial disorder, various key hidden players such as deficit of acetylcholine (ACh), tau-protein aggregation, and oxidative stress have been associated with the incidence and progress of AD. In pursuit of improving efficacy and expanding the range of pharmacological activities of current AD drugs, the molecular hybridization method is also used intensively. Five-membered heterocyclic systems such as thiadiazole scaffolds have previously been shown to have therapeutic activity. Thiadiazole analogs as an anti-oxidant compound have been known to include a wide range of biological activity from anti-cancer to anti-Alzheimer properties. The suitable pharmacokinetic and physicochemical properties of the thiadiazole scaffold have introduced it as a therapeutic target in medicinal chemistry. The current review portrays the critical role of the thiadiazole scaffold in the design of various compounds with potential effects in the treatment of Alzheimer's disease. Furthermore, the rationale used behind hybrid-based design strategies and the outcomes achieved through the hybridization of Thiadiazole analogs with various core structures have been discussed. In addition, the data in the present review may help researchers in the design of new multidrug combinations that may provide new options for the treatment of AD.

Hesperidin methylchalcone (HMC) hinders amyloid-β induced Alzheimer's disease by attenuating cholinesterase activity, macromolecular damages, oxidative stress and apoptosis via regulating NF-κB and Nrf2/HO-1 pathways

Phytocompounds therapy has recently emerged as an effective strategy to treat Alzheimer's disease. Herein, the protective effect of hesperidin methylchalcone (HMC) was evaluated through Alzheimer's disease models of Neuro-2a cells and Wistar rats. The in vitro results showed that HMC possesses significant ability to inhibit the acetylcholinesterase enzyme and exhibiting anti-aggregation and disaggregation properties. Furthermore, HMC could protect the Neuro-2a cells against Aβ-induced neurotoxicity. Simultaneously, HMC treatment significantly improved the cognitive deficits caused by Aβ-peptide on spatial memory in Wistar rats. HMC significantly enhanced the cholinergic effects by inhibiting AChE, BuChE, β-secretase activity, caspase-3 activity, and attenuating macromolecular damages and apoptosis. Notably, HMC reduced the Aβ-induced oxidative stress by activating the antioxidative defence enzymes. In addition, the HMC treatment suppressed the expression of immunocytokines such as p-NF-κB p65, p-IκBα, induced by Aβ; whereas upregulating Nrf2, HO-1 in brain homogenate. These results suggest that HMC could attenuate Aβ-induced neuroinflammation in brain via suppressing NF-κB signalling pathway and activating the Nrf2/HO-1 pathway, thereby improving memory and cognitive impairments in Wistar rats. Overall, the present study reports that HMC can act as a potent candidate with multi-faceted neuroprotective potential against Aβ-induced memory dysfunction in Wistar rats for the treatment of Alzheimer's disease.

Photobiomodulation in Alzheimer's Disease-A Complementary Method to State-of-the-Art Pharmaceutical Formulations and Nanomedicine?

Alzheimer's disease (AD), as a neurodegenerative disorder, usually develops slowly but gradually worsens. It accounts for approximately 70% of dementia cases worldwide, and is recognized by WHO as a public health priority. Being a multifactorial disease, the origins of AD are not satisfactorily understood. Despite huge medical expenditures and attempts to discover new pharmaceuticals or nanomedicines in recent years, there is no cure for AD and not many successful treatments are available. The current review supports introspection on the latest scientific results from the specialized literature regarding the molecular and cellular mechanisms of brain photobiomodulation, as a complementary method with implications in AD. State-of-the-art pharmaceutical formulations, development of new nanoscale materials, bionanoformulations in current applications and perspectives in AD are highlighted. Another goal of this review was to discover and to speed transition to completely new paradigms for the multi-target management of AD, to facilitate brain remodeling through new therapeutic models and high-tech medical applications with light or lasers in the integrative nanomedicine of the future. In conclusion, new insights from this interdisciplinary approach, including the latest results from photobiomodulation (PBM) applied in human clinical trials, combined with the latest nanoscale drug delivery systems to easily overcome protective brain barriers, could open new avenues to rejuvenate our central nervous system, the most fascinating and complex organ. Picosecond transcranial laser stimulation could be successfully used to cross the blood-brain barrier together with the latest nanotechnologies, nanomedicines and drug delivery systems in AD therapy. Original, smart and targeted multifunctional solutions and new nanodrugs may soon be developed to treat AD.

N-Substituted piperidine-3-carbohydrazide-hydrazones against Alzheimer's disease: Synthesis and evaluation of cholinesterase, beta-amyloid inhibitory activity, and antioxidant capacity

A series of piperidine-3-carbohydrazide-hydrazones bearing phenylethyl, phenylpropyl, and phenylbutyl substituents on piperidine nitrogen were designed and synthesized as cholinesterase (ChE) inhibitors. The title compounds were screened for acetylcholinesterase (AChE), butyrylcholinesterase (BuChE) inhibitory activities and antioxidant capacities, and the active ones for Aβ₄₂ self-aggregation inhibition, in vitro. The chemiluminescence method was used to determine the effect of the selected compounds on the reactive oxygen species (ROS) levels in brain tissue. Physicochemical properties were calculated by the MOE program. Kinetic analysis and molecular modeling studies were also carried out for the most active compounds. Generally, the final compounds exhibited moderate to good AChE or BuChE inhibitory activity. Among them, 3g and 3j showed the most potent activity against AChE (IC₅₀  = 4.32 µM) and BuChE (IC₅₀  = 1.27 µM), respectively. The kinetic results showed that both compounds exhibited mixed-type inhibition. Among the selected compounds, nitro derivatives (3g, 4g, and 5g) provided better Aβ₄₂ inhibition. According to the chemiluminescence assay, 4i exhibited the most active superoxide free-radical scavenger activity and 3g, 3j, and 4i showed similar scavenger activity on other ROS. All results suggested that 3g, 3j, and 4i have good AChE/BuChE, Aβ₄₂ inhibitory potentials and antioxidant capacities and can therefore be suggested as promising multifunctional agents to combat Alzheimer's disease.

Chemical Characterization of Different Extracts of Justicia secunda Vahl and Determination of Their Anti-Oxidant, Anti-Enzymatic, Anti-Viral, and Cytotoxic Properties

Justicia secunda Vahl. is a traditional medicinal plant in tropical regions, including West Africa. The present study examined the chemical profiles and biological properties of J. secunda extracts obtained with different solvents (dichloromethane, ethyl acetate, methanolic and aqueous: macerated and infused). Chemical components were characterized by liquid chromatography-mass spectrometry (LC-MS), and over 50 compounds were identified, including flavonoids, phenolic acids, and alkaloids. Antioxidant, enzyme inhibitory, cytotoxic, and antiviral properties were selected as biological properties. Total phenolic and flavonoid contents in methanol (58.07 mg gallic acid equivalent (GAE)/g and 13.07 mg rutin equivalent (RE)/g) and water (infused) (36.34 mg GAE/g and 8.52 mg RE/g) were higher than in other extracts. Consistent with the levels of total bioactive components, the methanol and water extracts exhibited stronger antioxidant abilities. However, the dichloromethane and ethyl acetate extracts were more active on α-amylase and α-glucosidase than other extracts. Aqueous extracts exerted selective anticancer properties toward human pharyngeal cancer cell lines, whereas the methanolic extract decreased the human herpesvirus type-1 (HHV-1) infectious titer by 2.16 log and the viral load by 1.21 log. Overall, J. secunda could be considered a multifunctional bioactive raw material in the preparation of potent applications to manage diseases related to oxidative stress, including cancer, diabetes, and Alzheimer's.

Conjugates of Tacrine and Salicylic Acid Derivatives as New Promising Multitarget Agents for Alzheimer's Disease

A series of previously synthesized conjugates of tacrine and salicylamide was extended by varying the structure of the salicylamide fragment and using salicylic aldehyde to synthesize salicylimine derivatives. The hybrids exhibited broad-spectrum biological activity. All new conjugates were potent inhibitors of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) with selectivity toward BChE. The structure of the salicylamide moiety exerted little effect on anticholinesterase activity, but AChE inhibition increased with spacer elongation. The most active conjugates were salicylimine derivatives: IC₅₀ values of the lead compound 10c were 0.0826 µM (AChE) and 0.0156 µM (BChE), with weak inhibition of the off-target carboxylesterase. The hybrids were mixed-type reversible inhibitors of both cholinesterases and displayed dual binding to the catalytic and peripheral anionic sites of AChE in molecular docking, which, along with experimental results on propidium iodide displacement, suggested their potential to block AChE-induced β-amyloid aggregation. All conjugates inhibited Aβ₄₂ self-aggregation in the thioflavin test, and inhibition increased with spacer elongation. Salicylimine 10c and salicylamide 5c with (CH₂)₈ spacers were the lead compounds for inhibiting Aβ₄₂ self-aggregation, which was corroborated by molecular docking to Aβ₄₂. ABTS^•+-scavenging activity was highest for salicylamides 5a-c, intermediate for salicylimines 10a-c, low for F-containing salicylamides 7, and non-existent for methoxybenzoylamides 6 and difluoromethoxybenzoylamides 8. In the FRAP antioxidant (AO) assay, the test compounds displayed little or no activity. Quantum chemical analysis and molecular dynamics (MD) simulations with QM/MM potentials explained the AO structure-activity relationships. All conjugates were effective chelators of Cu²⁺, Fe²⁺, and Zn²⁺, with molar compound/metal (Cu²⁺) ratios of 2:1 (5b) and ~1:1 (10b). Conjugates exerted comparable or lower cytotoxicity than tacrine on mouse hepatocytes and had favorable predicted intestinal absorption and blood-brain barrier permeability. The overall results indicate that the synthesized conjugates are promising new multifunctional agents for the potential treatment of AD.

Chemical synthesis and antifouling activity of monoterpene-furan hybrid molecules

Geraniol, a monoterpene, and furan are structural motifs that exhibit antifouling activity. In this study, monoterpene-furan hybrid molecules with potentially enhanced antifouling activity were designed and synthesized. The nine synthetic hybrids showed antifouling activity against the cypris larvae of the barnacle Balanus (Amphibalanus) amphitrite with EC₅₀ values of 1.65-4.70 μg mL^-1. This activity is higher than that of geraniol and the reference furan compound. This hybridization approach to increase antifouling activity is useful and can also be extended to other active structural units.

Development of new Alzheimer's disease drug candidates using donepezil as a key model

Alzheimer's disease (AD) is one of the most prevalent geriatric diseases and a significant cause of high mortality. This crippling disorder is becoming more prevalent at an unprecedented rate, which has led to an increase in the financial cost of caring. It is a pathologically complicated, multifactorial disease characterized by β-amyloid precipitation, β-amyloid oligomer production, decrease in cholinergic function, and dysregulation of other neurotransmitter systems. Due to the pathogenic complexity of AD, multitarget drugs that can simultaneously alternate multiple biological targets may enhance the therapeutic efficacy. Donepezil (DNP) is the most potent approved drug for the treatment of AD. It has a remarkable effect on a number of AD-related processes, including cholinesterase activity, anti-Aβ aggregation, oxidative stress, and more. DNP resembles an excellent scaffold to be hybridized with other pharmacophoric moieties having biological activity against AD pathological factors. There have been significant attempts made to modify the structure of DNP to create new bioactive chemical entities with novel structural patterns. In this review, we highlight recent advances in the development of multiple-target DNP-hybridized models for the treatment of AD that can be used in the future in the rational design of new potential AD therapeutics. The design and development of new drug candidates for the treatment of AD using DNP as a molecular scaffold have also been reviewed and summarized.

Discovery of pyrrole derivatives as acetylcholinesterase-sparing butyrylcholinesterase inhibitor

Inspired by the crucial roles of (hetero)aryl rings in cholinesterase inhibitors and the pyrrole ring in new drug discovery, we synthesized 19 pyrrole derivatives and investigated their cholinesterase inhibitory activity. As a result, compounds 3o, 3p, and 3s with a 1,3-diaryl-pyrrole skeleton showed high selectivity toward BChE over AChE with a best IC₅₀ value of 1.71 ± 0.087 µM, which were comparable to donepezil. The pharmaceutical potential of these structures was further predicted and compounds 3o and 3p were proved to meet well with the Lipinsky's five rules. In combination of the inhibition kinetic studies with the results of molecular docking, we concluded that compound 3p inhibited BChE in a mixed competitive mode. This research has proved the potential of the 1,3-diaryl-pyrrole skeleton as a kind of selective BChE inhibitor.

Alternative Pharmacological Strategies for the Treatment of Alzheimer's Disease: Focus on Neuromodulator Function

Alzheimer's disease (AD) is a neurodegenerative disorder, comprising 70% of dementia diagnoses worldwide and affecting 1 in 9 people over the age of 65. However, the majority of its treatments, which predominantly target the cholinergic system, remain insufficient at reversing pathology and act simply to slow the inevitable progression of the disease. The most recent neurotransmitter-targeting drug for AD was approved in 2003, strongly suggesting that targeting neurotransmitter systems alone is unlikely to be sufficient, and that research into alternate treatment avenues is urgently required. Neuromodulators are substances released by neurons which influence neurotransmitter release and signal transmission across synapses. Neuromodulators including neuropeptides, hormones, neurotrophins, ATP and metal ions display altered function in AD, which underlies aberrant neuronal activity and pathology. However, research into how the manipulation of neuromodulators may be useful in the treatment of AD is relatively understudied. Combining neuromodulator targeting with more novel methods of drug delivery, such as the use of multi-targeted directed ligands, combinatorial drugs and encapsulated nanoparticle delivery systems, may help to overcome limitations of conventional treatments. These include difficulty crossing the blood-brain-barrier and the exertion of effects on a single target only. This review aims to highlight the ways in which neuromodulator functions are altered in AD and investigate how future therapies targeting such substances, which act upstream to classical neurotransmitter systems, may be of potential therapeutic benefit in the sustained search for more effective treatments.

Resveratrol Analogues as Dual Inhibitors of Monoamine Oxidase B and Carbonic Anhydrase VII: A New Multi-Target Combination for Neurodegenerative Diseases?

Neurodegenerative diseases (NDs) are described as multifactorial and progressive syndromes with compromised cognitive and behavioral functions. The multi-target-directed ligand (MTDL) strategy is a promising paradigm in drug discovery, potentially leading to new opportunities to manage such complex diseases. Here, we studied the dual ability of a set of resveratrol (RSV) analogs to inhibit two important targets involved in neurodegeneration. The stilbenols 1−9 were tested as inhibitors of the human monoamine oxidases (MAOs) and carbonic anhydrases (CAs). The studied compounds displayed moderate to excellent in vitro enzyme inhibitory activity against both enzymes at micromolar/nanomolar concentrations. Among them, the best compound 4 displayed potent and selective inhibition against the MAO-B isoform (IC50 MAO-A 0.43 µM vs. IC50 MAO-B 0.01 µM) with respect to the parent compound resveratrol (IC50 MAO-A 13.5 µM vs. IC50 MAO-B > 100 µM). It also demonstrated a selective inhibition activity against hCA VII (KI 0.7 µM vs. KI 4.3 µM for RSV). To evaluate the plausible binding mode of 1−9 within the two enzymes, molecular docking and dynamics studies were performed, revealing specific and significant interactions in the active sites of both targets. The new compounds are of pharmacological interest in view of their considerably reduced toxicity previously observed, their physicochemical and pharmacokinetic profiles, and their dual inhibitory ability. Compound 4 is noteworthy as a promising lead in the development of MAO and CA inhibitors with therapeutic potential in neuroprotection.

New Multifunctional Agents for Potential Alzheimer's Disease Treatment Based on Tacrine Conjugates with 2-Arylhydrazinylidene-1,3-Diketones

Alzheimer's disease (AD) is considered a modern epidemic because of its increasing prevalence worldwide and serious medico-social consequences, including the economic burden of treatment and patient care. The development of new effective therapeutic agents for AD is one of the most urgent and challenging tasks. To address this need, we used an aminoalkylene linker to combine the well-known anticholinesterase drug tacrine with antioxidant 2-tolylhydrazinylidene-1,3-diketones to create 3 groups of hybrid compounds as new multifunctional agents with the potential for AD treatment. Lead compounds of the new conjugates effectively inhibited acetylcholinesterase (AChE, IC50 0.24-0.34 µM) and butyrylcholinesterase (BChE, IC50 0.036-0.0745 µM), with weak inhibition of off-target carboxylesterase. Anti-AChE activity increased with elongation of the alkylene spacer, in agreement with molecular docking, which showed compounds binding to both the catalytic active site and peripheral anionic site (PAS) of AChE, consistent with mixed type reversible inhibition. PAS binding along with effective propidium displacement suggest the potential of the hybrids to block AChE-induced β-amyloid aggregation, a disease-modifying effect. All of the conjugates demonstrated metal chelating ability for Cu2+, Fe2+, and Zn2+, as well as high antiradical activity in the ABTS test. Non-fluorinated hybrid compounds 6 and 7 also showed Fe3+ reducing activity in the FRAP test. Predicted ADMET and physicochemical properties of conjugates indicated good CNS bioavailability and safety parameters acceptable for potential lead compounds at the early stages of anti-AD drug development.

Rational drug design strategies for the development of promising multi-target directed indole hybrids as Anti-Alzheimer agents

Alzheimer's disease (AD) is a neurological disorder that leads to dementia i.e., progressive memory loss accompanied with worsening of thinking ability of an individual. The cause of AD is not fully understood but it progresses with age where brain cells gradually die over time. According to the World Health Organization (WHO), currently 50 million people worldwide are affected by dementia and 60-70% of the cases belong to AD. Cumulative research over the past few decades have shown that molecules that act at a single target possess limited efficacy since these investigational drugs are not able to act against complex pathologies and thus do not provide permanent cure. Designing of multi-target directed ligands (MTDLs) appears to be more beneficial and a rational approach to treat chronic complex diseases including neurodegenerative diseases. Recently, MTDLs are being extensively researched by the medicinal chemists for the development of drugs for the treatment of various multifactorial diseases. Indole is one of the privileged scaffolds which is considered as an essential mediator between the gut-brain axis because of its neuroprotective, anti-inflammatory, β-amyloid anti-aggregation and antioxidant activities. Herein, we have reviewed the potential of some indole-hybrids acting at multiple targets in the pathogenesis of AD. We have reviewed research articles from the year 2014-2021 from various scientific databases and highlighted the synthetic strategies, mechanisms of neuroprotection, toxicity, structure activity relationships and molecular docking studies of various indole-hybrid derivatives. This literature review of published data on indole derivatives indicated that developing indole hybrids have improved the pharmacokinetic profile with lower toxicity, provided synergistic effect, helped to develop more potent compounds and prevented drug-drug interactions. It is evident that this class of compounds have potential to inhibit multiple enzymes targets involved in the pathogenesis of AD and therefore indole hybrids as MTDLs may play an important role in the development of anti-AD molecules.

Ecdysteroids as Potent Enzyme Inhibitors and Verification of Their Activity Using In Vitro and In Silico Docking Studies

Ecdysteroids represent arthropods’ steroidal hormones, and they exist in about 5–6% of plant species. In this study, the enzyme inhibitory activity of 20 ecdysteroids was assessed for the first time via determining their inhibition versus acetylcholinesterase, butyrylcholinesterase, tyrosinase, as well as α-amylase enzymes. Furthermore, 20-Hydroxyecdysone-2,3,22-tri-O-acetate (4) showed the highest inhibition of acetylcholinesterase and butyrylcholinesterase with values of 5.56 and 4.76 mg GALAE/g, respectively. All ecdysteroids displayed tyrosinase inhibitory effects, whereas the most potent was viticosterone E (7) with 78.88 mg KAE/g. Most ecdysteroids had similar amylase inhibitory properties; meanwhile, the best α-amylase inhibitory potential was observed with viticosterone E-diacetonide (18) (0.35 mmol ACAE/g). Most of the tested compounds showed tyrosinase inhibitory potential; therefore, they were exposed to molecular docking evaluation using the tyrosinase enzyme. Viticosterone E (7) showed the best ranking score with a docking score of −5.716 Kcal/mol and made three separate H-bonds with Gly281, Asn81, and His85. From ADMET /TOPKAT in silico evaluation, it was obvious that most of the compounds displayed reasonable pharmacodynamic and pharmacokinetic properties; however, their toxicity should be carefully monitored by adjusting their doses while investigating their activity after incorporation into dosage forms. Principal component analysis (PCA) based upon the in vitro and in silico data was carried out to visualize the differences between the tested compounds better. PCA score plot successfully classifies the compounds into four main clusters that, in turn, reflects the similarities and differences among the clustered compounds with respect to their biological, pharmacokinetic, and pharmacodynamic properties that are mainly influenced by the similarity in the chemical structure. Thus, ecdysteroids can act as effective drug entities for alleviating several disorders owing to their enzyme inhibitory potential.

Comparative Content, Biological and Anticancer Activities of Heracleum humile Extracts Obtained by Ultrasound-Assisted Extraction Method

As the safety and effectiveness of synthetic drugs remain in doubt, researchers are trying to develop natural medicines from medicinal plants. Herein, ethyl acetate, methanol and water extracts from the Heracleum humile plant were obtained by an ultrasonic-assisted extraction process and the aim was to evaluate some biological effects of the extracts due to the limited data on the pharmacological properties of Heracleum humile in the literature. Weak antibacterial activity was observed on tested bacterial species. The minimum inhibitory concentration and the minimum bactericidal concentration values ranged from 250 to 500 μg/mL. In addition, cytotoxic activity was determined using the MTT test. The strongest findings were determined for ethyl acetate extract on the MDA-MB-231 cell lines at the 48^th  hour (IC₅₀ :97.94 μg/mL), followed by the MCF-7 cell lines at the 24^th  hour (IC₅₀ :103.9 μg/mL). All extracts of Heracleum humile contained mainly flavonoids, phenolic acids and their derivatives, i. e., well-known compounds that possess numerous biological activities such as antioxidant, anti-inflammatory, anticancer, antimicrobial etc. The study results could provide important information that Heracleum humile could be a potential candidate as a natural enzyme inhibitor. It can be concluded that these extracts could be useful in the elementary step of improving novel plant-derived multifunctional pharmaceuticals.

Design, Synthesis, and In Vitro, In Silico and In Cellulo Evaluation of New Pyrimidine and Pyridine Amide and Carbamate Derivatives as Multi-Functional Cholinesterase Inhibitors

Alzheimer disease is an age-linked neurodegenerative disorder representing one of the greatest medical care challenges of our century. Several drugs are useful in ameliorating the symptoms, even if none could stop or reverse disease progression. The standard approach is represented by the cholinesterase inhibitors (ChEIs) that restore the levels of acetylcholine (ACh) by inhibiting the acetylcholinesterase (AChE). Still, their limited efficacy has prompted researchers to develop new ChEIs that could also reduce the oxidative stress by exhibiting antioxidant properties and by chelating the main metals involved in the disease. Recently, we developed some derivatives constituted by a 2-amino-pyrimidine or a 2-amino-pyridine moiety connected to various aromatic groups by a flexible amino-alkyl linker as new dual inhibitors of AChE and butyrylcholinesterase (BChE). Following our previous studies, in this work we explored the role of the flexible linker by replacing the amino group with an amide or a carbamic group. The most potent compounds showed higher selectivity against BChE in respect to AChE, proving also to possess a weak anti-aggregating activity toward Aβ₄₂ and tau and to be able to chelate Cu²⁺ and Fe³⁺ ions. Molecular docking and molecular dynamic studies proposed possible binding modes with the enzymes. It is noteworthy that these compounds were predicted as BBB-permeable and showed low cytotoxicity on the human brain cell line.

Design, Synthesis and Biological Evaluation of New 3,4-Dihydro-2(1H)-Quinolinone-Dithiocarbamate Derivatives as Multifunctional Agents for the Treatment of Alzheimer’s Disease

Background

Alzheimer’s disease (AD) belongs to neurodegenerative disease, and the increasing number of AD patients has placed a heavy burden on society, which needs to be addressed urgently. ChEs/MAOs dual-target inhibitor has potential to treat AD according to reports.

Purpose

To obtain effective multi-targeted agents for the treatment of AD, a novel series of hybrid compounds were designed and synthesized by fusing the pharmacophoric features of 3,4-dihydro-2 (1H)-quinolinone and dithiocarbamate.

Methods

All compounds were evaluated for their inhibitory abilities of ChEs and MAOs. Then, further biological activities of the most promising candidate 3e were determined, including the ability to cross the blood-brain barrier (BBB), kinetics and molecular model analysis, cytotoxicity in vitro and acute toxicity studies in vivo.

Results

Most compounds showed potent and clear inhibition to AChE and MAOs. Among them, compound 3e was considered to be the most effective and balanced inhibitor to both AChE and MAOs (IC₅₀=0.28 µM to eeAChE; IC₅₀=0.34 µM to hAChE; IC₅₀=2.81 µM to hMAO-B; IC₅₀=0.91 µM to hMAO-A). In addition, 3e showed mixed inhibition of hAChE and competitive inhibition of hMAO-B in the enzyme kinetic studies. Further studies indicated that 3e could penetrate the BBB and showed no toxicity on PC12 cells and HT-22 cells when the concentration of 3e was lower than 12.5 µM. More importantly, 3e lacked acute toxicity in mice even at high dose (2500 mg/kg, P.O.).

Conclusion

This work indicated that compound 3e with a six-carbon atom linker and a piperidine moiety at terminal position was a promising candidate and was worthy of further study.

Neuroprotective Effects of Cholinesterase Inhibitors: Current Scenario in Therapies for Alzheimer's Disease and Future Perspectives

Alzheimer's disease (AD) is a slowly progressive neurodegenerative disease conceptualized as a continuous process, ranging from mild cognitive impairment (MCI), to the mild, moderate, and severe clinical stages of AD dementia. AD is considered a complex multifactorial disease. Currently, the use of cholinesterase inhibitors (ChEI), such as tacrine, donepezil, rivastigmine, and galantamine, has been the main treatment for AD patients. Interestingly, there is evidence that ChEI also promotes neuroprotective effects, bringing some benefits to AD patients. The mechanisms by which the ChEI act have been investigated in AD. ChEI can modulate the PI3K/AKT pathway, which is an important signaling cascade that is capable of causing a significant functional impact on neurons by activating cell survival pathways to promote neuroprotective effects. However, there is still a huge challenge in the field of neuroprotection, but in the context of unravelling the details of the PI3K/AKT pathway, a new scenario has emerged for the development of more efficient drugs that act on multiple protein targets. Thus, the mechanisms by which ChEI can promote neuroprotective effects and prospects for the development of new drug candidates for the treatment of AD are discussed in this review.

Conjugates of Tacrine with Salicylamide as Promising Multitarget Agents for Alzheimer's Disease

New conjugates of tacrine and salicylamide with alkylene spacers were synthesized and evaluated as potential multifunctional agents for Alzheimer's disease (AD). The compounds exhibited high acetylcholinesterase (AChE, IC₅₀ to 0.224 μM) and butyrylcholinesterase (BChE, IC₅₀ to 0.0104 μM) inhibitory activities. They were also rather poor inhibitors of carboxylesterase, suggesting a low tendency to exert potential unwanted drug-drug interactions in clinical use. The conjugates were mixed-type reversible inhibitors of both cholinesterases and demonstrated dual binding to the catalytic and peripheral anionic sites of AChE in molecular docking that, along with experimental results on propidium iodide displacement, suggest their potential to block AChE-induced β-amyloid aggregation. The new conjugates exhibited high ABTS^.+ -scavenging activity. N-(6-(1,2,3,4-Tetrahydroacridin-9-ylamino)hexyl)salicylamide is a lead compound that also demonstrates metal chelating ability toward Cu²⁺ , Fe²⁺ and Zn²⁺ . Thus, the new conjugates have displayed the potential to be multifunctional anti-AD agents for further development.

Pharmacophore mapping of the crucial mediators of acetylcholinesterase and butyrylcholinesterase dual inhibition in Alzheimer's disease

Optimization and re-optimization of bioactive molecules using in silico methods have found application in the design of more active ones. Herein, we applied a pharmacophore modeling approach to screen potent dual inhibitors of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) aimed at Alzheimer's disease (AD) treatment. The investigation entails molecular dynamics simulation, docking, pharmacophore modeling, drug-like screening, and binding energy analysis. We prepared a pharmacophore model from approved inhibitors of AChE and BuChE to predict the crucial moieties required for optimum molecular interaction with these proteins. The obtained pharmacophore model, used for database screening via some critical criteria, showed 229 hit molecules. Further analyses showed 42 likely dual inhibitors of AChE/BuChE with drug-like and pharmacokinetics properties the same as the approved cholinesterase inhibitors. Finally, we identified 14 dual molecules with improved potentials over the existing inhibitors and simulated ZINC92385797 bound to human AChE and BuChE structure after noticing that these 14 molecules are similar. The selected compound maintained relative stability at the active sites of both proteins over 120 ns simulation. Our integrated protocols showed the pertinent recipes of anti-AD drug design through the in silico pipeline.

Tea and coffee polyphenols and their biological properties based on the latest in vitro investigations

Tea and coffee contain numerous polyphenolic compounds that exhibit health-promoting properties for humans, including antioxidant and neuroprotective properties, and can also take part in the treatment of covid-19 and improve fertility. This review, presents the activity of polyphenols found in different types of tea and coffee and describes the effects of tea fermentation and coffee roasting on their polyphenol composition and antioxidant properties. Polyphenol oxidase activity is reduced in the fermentation process; therefore black tea contains significantly less polyphenolic compounds compared to green and white tea. Epigallocatechin-3-gallate - a polyphenol from tea - effectively has been shown to inhibit the activity of SARS-CoV-2 as it blocked binding of coronavirus 2 to human angiotensin converting enzyme 2, decreased the expression of inflammatory factors in the blood, including tumor necrosis factor-α and interleukin-6, and significantly increased the overall fertilization efficiency in animals. Coffee roasting process influences both the content of polyphenols and the oxidative activity. The lowest levels of active compounds such as caffeine, chlorogenic acid and coffee acids are identified in roasted coffee beans. On the other hand, light coffee and green coffee show the strongest cytotoxic potential and antioxidant properties, and thus the greatest ability to decrease apoptosis by stopping the cell cycle in the S phase. Proteins, such as components of milk, can strongly bind/interact with phenolic compounds (especially, the CGAs) contain in coffee, which may explain the negative influence of milk on its antioxidant properties. Coffee polyphenols have also antiproliferative and antiesterase activities, which may be important in prevention of cancer and neurodegenerative disorders, respectively. In this review, biological properties of tea and coffee polyphenols, observed mainly in in vitro studies have been described. Based on these findings, future directions of the research works on these compounds have been suggested.

Tea and coffee polyphenols and their biological properties based on the latest in vitro investigations

Tea and coffee contain numerous polyphenolic compounds that exhibit health-promoting properties for humans, including antioxidant and neuroprotective properties, and can also take part in the treatment of covid-19 and improve fertility. This review, presents the activity of polyphenols found in different types of tea and coffee and describes the effects of tea fermentation and coffee roasting on their polyphenol composition and antioxidant properties. Polyphenol oxidase activity is reduced in the fermentation process; therefore black tea contains significantly less polyphenolic compounds compared to green and white tea. Epigallocatechin-3-gallate - a polyphenol from tea - effectively has been shown to inhibit the activity of SARS-CoV-2 as it blocked binding of coronavirus 2 to human angiotensin converting enzyme 2, decreased the expression of inflammatory factors in the blood, including tumor necrosis factor-α and interleukin-6, and significantly increased the overall fertilization efficiency in animals. Coffee roasting process influences both the content of polyphenols and the oxidative activity. The lowest levels of active compounds such as caffeine, chlorogenic acid and coffee acids are identified in roasted coffee beans. On the other hand, light coffee and green coffee show the strongest cytotoxic potential and antioxidant properties, and thus the greatest ability to decrease apoptosis by stopping the cell cycle in the S phase. Proteins, such as components of milk, can strongly bind/interact with phenolic compounds (especially, the CGAs) contain in coffee, which may explain the negative influence of milk on its antioxidant properties. Coffee polyphenols have also antiproliferative and antiesterase activities, which may be important in prevention of cancer and neurodegenerative disorders, respectively. In this review, biological properties of tea and coffee polyphenols, observed mainly in in vitro studies have been described. Based on these findings, future directions of the research works on these compounds have been suggested.

LC-MS/HRMS Analysis, Anti-Cancer, Anti-Enzymatic and Anti-Oxidant Effects of Boerhavia diffusa Extracts: A Potential Raw Material for Functional Applications

Boerhavia diffusa is a great tropical plant and is widely used for various traditional purposes. In the present study, we examined the influence of solvents (dichloromethane, ethyl acetate, methanol and infusion (water)) on chemical composition and biological capabilities of B. diffusa. An UHPLC-HRMS method was used to determine the chemical characterization. The biological ability was examined for antioxidant, enzyme inhibitory and anti-cancer effects. To evaluate antioxidant effects, different chemical methods (ABTS, DPPH, CUPRAC, FRAP, metal chelating and phosphomolybdenum) were applied. With regard to enzyme inhibitory properties, cholinesterases, amylase, glucosidase and tyrosinase were used. The MDA-MB-231 breast cancer cell line was chosen to determine anticancer activity. Based on the UHPLC-HRMS analysis, 37 specialized metabolites were dereplicated and identified in the studied extracts. Results revealed the presence of 15 hydroxybenzoic, hydroxycinnamic, acylquinic acids, and their glycosides, one rotenoid, seven flavonoids, 12 fatty acids and two other glycosides. Among the tested extracts, the methanol extract showed a stronger antioxidant ability compared with other extracts. The methanol extract also showed the best inhibitory effects on tyrosinase and glucosidase. In the anti-cancer evaluation, the methanol extract showed stronger anticancer effects compared with water extract. In summary, our observations can contribute to the establishment of B. diffusa as a potential candidate for functional applications in the preparation.