Combining in silico and in vitro approaches to evaluate the acetylcholinesterase inhibitory profile of some commercially available flavonoids in the management of Alzheimer’s disease

Triclosan-loaded aged microplastics exacerbate oxidative stress and neurotoxicity in Xenopus tropicalis tadpoles via increased bioaccumulation

Microplastics and chlorine-containing triclosan (TCS) are widespread in aquatic environments and may pose health risks to organisms. However, studies on the combined toxicity of aged microplastics and TCS are limited. To investigate the toxic effects and potential mechanisms associated with co-exposure to TCS adsorbed on aged polyethylene microplastics (aPE-MPs) at environmentally relevant concentrations, a 7-day chronic exposure experiment was conducted using Xenopus tropicalis tadpoles. The results showed that the overall particle size of aPE-MPs decreased after 30 days of UV aging, whereas the increase in specific surface area improved the adsorption capacity of aPE-MPs for TCS, resulting in the bioaccumulation of TCS under dual-exposure conditions in the order of aPE-TCS > PE-TCS > TCS. Co-exposure to aPE-MPs and TCS exacerbated oxidative stress and neurotoxicity to a greater extent than a single exposure. Significant upregulation of pro-symptomatic factors (IL-β and IL-6) and antioxidant enzyme activities (SOD and CAT) indicated that the aPE-TCS combination caused more severe oxidative stress and inflammation. Molecular docking revealed the molecular mechanism of the direct interaction between TCS and SOD, CAT, and AChE proteins, which explains why aPE-MPs promote the bioaccumulation of TCS, causing increased toxicity upon combined exposure. These results emphasize the need to be aware of the combined toxicity caused by the increased ability of aged microplastics to carry contaminants.

Pterocarpus soyauxii (Fabaceae) aqueous extract to prevent neuropsychiatric disorders associated with menopause by triggering ROS-dependent oxidative damage and inhibiting acetylcholinesterase, GABA-transaminase, and monoamine oxidase A: In vitro, in vivo, and in silico approaches

Pterocarpus soyauxii (PS) is traditionally used in Cameroon medicine to alleviate postmenopausal symptoms. Previous research has shown that it has tissue-selective potential and estrogen-mimetic effects on vaginal atrophy. Phytoestrogens like 7-O-acetyl formononetin, khrinone A, and 3',5'-dimethoxy-4-stilbenol were found in its water extract by UHPLC, but there is no evidence of its effects on neurological disorders linked to post-menopause (ND-PO). The study aimed to investigate the phytochemical profile of PS aqueous extract, assess its neuroprotective potential in rats, and explore possible underlying pathways. We used colorimetric assays to study the phytochemical profile of PS extract. Effects of the extract on behavioral parameters, neuronal signaling, and integrity in an 84-day ovariectomized rat model. Molecular docking was performed to assess the ability of 7-O-acetyl formononetin, an isoflavone contained in PS, to cross the BBB and its binding affinity to the active sites of AChE, MAO-A, and GABA-T. Besides, the anti-AChE/BChE, antioxidant, and anti-inflammatory effects of PS were assessed by in vitro tests. PS aqueous extract contains polyphenols (656.58 ± 9.18 mgEAG/100gMS), flavonoids (201.25 ± 5.52 mgEQ/100gDW), and tannins (18.42 ± 1.25 mg/100gDW). It slows down anxiety, depressive disorders, cellular disorganization, and neuronal death in the hippocampus, dentate gyrus, and neocortex. In silico modeling was a powerful tool to assess the 7-O-acetylformononetin's ability to cross the BBB and strongly bind and inhibit AChE, MAO-A, and GABA-T. Thus, by combining GABAergic, cholinergic, and serotoninergic modulation, PS aqueous extract also possesses remarkable anti-AChE/BChE in vitro and induces antioxidant and anti-inflammatory potential in macrophages. Such estromimetics, antioxidant, anti-inflammatory, cholinergic, and monoaminergic modulators represent promising activities to develop neuroprotective drugs with optimal therapeutic profiles for menopausal women.

Virtual display of targets: A new level to rise the current understanding of ochratoxin A toxicity from a molecular standpoint

Ochratoxin A (OTA) is a mycotoxin spread worldwide contaminating several food and feed commodities and rising concerns for humans and animals. OTA toxicity has been thoroughly assessed over the last 60 years revealing a variety of adverse effects, including nephrotoxicity, hepatotoxicity and possible carcinogenicity. However, the underpinning mechanisms of action have yet to be completely displayed and understood. In this framework, we applied a virtual pipeline based on molecular docking, dynamics and umbrella simulations to display new OTA potential targets. The results collected consistently identified OGFOD1, a key player in protein translation, as possibly inhibited by OTA and its 2'R diastereomer. This is consistent with the current knowledge of OTA's molecular toxicology and may fill some gaps from a mechanistic standpoint. This could pave the way for further dedicated analysis focusing their attention on the OTA-OGFOD1 interaction, expanding the current understanding of OTA toxicity at a molecular level.

In silico evaluation of some commercially available terpenoids as spike glycoprotein of SARS-CoV-2 - inhibitors using molecular dynamic approach

Coronavirus, an extremely contagious infections disease had a harmful effect on the world's population. It is a family of enveloped, single-stranded, positive-strand RNA viruses of Nidovirales order belongs to coroviridae family. At present, worldwide several lakhs of deaths and several billions of infections have been reported. Hence, the focus of the present study was to assess the SARS-CoV-2 enzyme inhibitory potential of certain commercially available terpenoids using Lamarckian genetic algorithm as a working principle and molecular dynamic studies was also performed. AutoDock 4.2 software was used to perform the computational docking calculations of terpenoids against SARS-CoV-2 enzyme. The terpenoids such as, Andrographolide, Betulonic acid, Erythrodiol, Friedelin, Mimuscopic acid, Moronic acid, and Retinol were selected based on the drug likeness properties. Remdesivir a well-known anti-viral drug was selected as the standard drug. Molecular dynamic simulation studies were carried using Desmond module of Schrodinger Suite. In the current study we observed that, Friedelin was exhibited excellent SARS-CoV-2 enzyme inhibitory potential than the standard drug and other selected terpenoids. Friedelin and the standard Remdesivir was undergone the molecular dynamic studies and Friedelin showed a good number of hydrogen bonds over the simulation time of 100 ns. Based on the in silico computational evaluation, it can be concluded that Friedelin could be worthwhile terpenoid against SARS-CoV-2 spike protein. A further study on Friedelin is required to develop a potential chemical entity against the management of COVID disease.Communicated by Ramaswamy H. Sarma.

Docking, Synthesis, and In vitro Anti-depressant Activity of Certain Isatin Derivatives

BACKGROUND

In vitro, the molecular docking method has been suggested for estimating the biological affinity of the pharmacophores with physiologically active compounds. It is the latter stage in molecular docking, and the docking scores are examined using the AutoDock 4.2 tool program. The chosen compounds can be evaluated for in vitro activity based on the binding scores, and the IC50 values can be computed.

OBJECTIVE

The purpose of this work was to create methyl isatin compounds as potential antidepressants, compute physicochemical characteristics, and carry out docking analysis.

METHODS

The protein data bank of the RCSB (Research Collaboratory for Structural Bioinformatics) was used to download the PDB structures of monoamine oxidase (PDB ID: 2BXR) and indoleamine 2,3-dioxygenase (PDB ID: 6E35). Based on the literature, methyl isatin derivatives were chosen as the lead chemicals. By determining their IC50 values, the chosen compounds were tested for in vitro anti-depressant activity.

RESULTS

The binding scores for the interactions of SDI 1 and SD 2 with indoleamine 2,3 dioxygenase were found to be -10.55 kcal/mol and -11.08 kcal/mol, respectively, while the scores for their interactions with monoamine oxidase were found to be -8.76 kcal/mol and -9.28 kcal/mol, respectively, using AutoDock 4.2. The relationship between biological affinity and pharmacophore electrical structure was examined using the docking technique. The chosen compounds were tested for their ability to inhibit MAO, and the IC50 values for each were found to be 51.20 and 56, respectively.

CONCLUSION

This investigation has identified many novel and effective MAO-A inhibitors from the family of chemicals known as methyl isatin derivatives. Lead optimization was applied to the SDI 1 and SDI 2 derivatives. The superior bioactivity, pharmacokinetic profile, BBB penetration, pre-ADMET profiles, such as HIA (human intestinal absorption) and MDCK (Madin-Darby canine kidney), plasma protein binding, toxicity assessment, and docking outcomes, have been obtained. According to the study, synthesised isatin 1 and SDI 2 derivatives exhibited a stronger MAO inhibitory activity and effective binding energy, which may help prevent stress-induced depression and other neurodegenerative disorders caused by a monoamine imbalance.

Mechanistic insights into phenanthrene-triggered oxidative stress-associated neurotoxicity, genotoxicity, and behavioral disturbances toward the brandling worm (Eisenia fetida) brain: The need for an ecotoxicological evaluation

In this study, earthworm (Eisenia fetida) brain was chosen as targeted receptors to probe the mechanisms of oxidative stress-related neurotoxicity, genotoxicity, and behavioral disturbances triggered by PHE. Results showed that PHE stress can initiate significant amounts of ROS, thus triggering oxidative stress in E. fetida brain. These effects were accompanied by a significant increase of damage to macromolecules DNA and lipids, resulting in severe oxidative effects. PHE exposure can induce AChE inhibition by ROS-induced injury and the accumulation of excess ACh at the nicotinic post-synaptic membrane, thus inducing aggravated neurological dysfunction and neurotoxicity of E. fetida through an oxidative stress pathway. Moreover, the burrowing behavior of earthworms was disturbed by oxidative stress-induced neurotoxicity after exposure to PHE. Furthermore, the abnormal mRNA expression profiles of oxidative stress- and neurotoxicity-related genes in worm brain were induced by PHE stress. The IBR results suggested that E. fetida brain was suffered more serious damage caused by PHE under higher doses and long-term exposure. Taken together, PHE exposure can trigger oxidative stress-mediated neurotoxicity and genotoxicity in worm brain and behavioral disorder through ROS-induced damage. This study is of great significance to evaluate the harmful effects of PHE and its mechanisms on soil ecological health.

Ecotoxicological evaluation of oxidative stress-mediated neurotoxic effects, genetic toxicity, behavioral disorders, and the corresponding mechanisms induced by fluorene-contaminated soil targeted to earthworm (Eisenia fetida) brain

Fluorene is a commonly identified PAH pollutant in soil and exhibits various worrisome hazardous effects to soil organisms. Currently, the toxicity profiles of fluorene on earthworm brain are rare, and the mechanisms and their corresponding pathways involved in fluorene-triggered neurotoxicity, genotoxicity, and behavior changes have not been reported hitherto. Herein, earthworm (Eisenia fetida) brain was chosen as targeted receptor to explore the neurotoxic effects, genetic toxicity, behavioral disorders, and related mechanisms caused by fluorene-induced oxidative stress pathways. The results showed excess fluorene initiated the release of excessive quantities of ROS in earthworm brain, which have caused oxidative stress and accompanied by serious oxidative effects, including LPO (lipid peroxidation) and DNA injury. To minimize the damage effects, the antioxidant defense mechanisms (antioxidant enzymes and non-enzymatic antioxidants) were activated, and entailed a decrease of the antioxidant capacity in E. fetida brain, which, in turn, causes further ROS-induced ROS release. Exposure of fluorene induced the abnormal mRNA expression of genes relevant to oxidative stress (e.g., GST, SOD, CAT, GPx, MT, and Hsp70) and neurotoxicity (e.g., H02, C04, D06, and E08) in E. fetida brain. Specifically, fluorene can bind directly to AChE, destroying the conformation of this protein, and even affecting its physiological functions. This occurrence caused the inhibition of AChE activity and excess ACh accumulation at the nicotinic post-synaptic membrane, finally triggering neurotoxicity by activation of pathways related to oxidative stress. Moreover, the avoidance responses and burrowing behavior were obviously disturbed by oxidative stress-induced neurotoxicity after exposure to fluorene. The results form IBR suggested more severe poisoning effects to E. fetida brain initiated by high-dose and long-term exposure of fluorene. Among, oxidative stress injury and genotoxic potential are more sensitive endpoint than others. Collectively, fluorene stress can provoke potential neurotoxicity, genotoxicity, and behavioral disturbances targeted to E. fetida brain through the ROS-mediated pathways involving oxidative stress. These findings are of great significance to estimate the detrimental effects of fluorene and the corresponding mechanisms on soil eco-safety.

Density Functional Theory Calculations and Molecular Docking Analyses of Flavonoids for Their Possible Application against the Acetylcholinesterase and Triose-Phosphate Isomerase Proteins of Rhipicephalus microplus

Ticks and tick-borne diseases constitute a substantial hazard to the livestock industry. The rising costs and lack of availability of synthetic chemical acaricides for farmers with limited resources, tick resistance to current acaricides, and residual issues in meat and milk consumed by humans further aggravate the situation. Developing innovative, eco-friendly tick management techniques, such as natural products and commodities, is vital. Similarly, searching for effective and feasible treatments for tick-borne diseases is essential. Flavonoids are a class of natural chemicals with multiple bioactivities, including the inhibition of enzymes. We selected eighty flavonoids having enzyme inhibitory, insecticide, and pesticide properties. Flavonoids' inhibitory effects on the acetylcholinesterase (AChE1) and triose-phosphate isomerase (TIM) proteins of Rhipicephalus microplus were examined utilizing a molecular docking approach. Our research demonstrated that flavonoids interact with the active areas of proteins. Seven flavonoids (methylenebisphloridzin, thearubigin, fortunellin, quercetagetin-7-O-(6-O-caffeoyl-β-d-glucopyranoside), quercetagetin-7-O-(6-O-p-coumaroyl-β-glucopyranoside), rutin, and kaempferol 3-neohesperidoside) were the most potent AChE1 inhibitors, while the other three flavonoids (quercetagetin-7-O-(6-O-caffeoyl-β-d-glucopyranoside), isorhamnetin, and liquiritin) were the potent inhibitors of TIM. These computationally-driven discoveries are beneficial and can be utilized in assessing drug bioavailability in both in vitro and in vivo settings. This knowledge can create new strategies for managing ticks and tick-borne diseases.

Phenolic Profile and Cholinesterase Inhibitory Properties of Three Chilean Altiplano Plants: Clinopodium gilliesii (Benth.) Kuntze [Lamiaceae], Mutisia acuminata Ruiz & Pav. var. hirsuta (Meyen) Cabrera, and Tagetes multiflora (Kunth) [Asteraceae]

This research aimed to identify the phenolic profile and composition of the aerial parts of three native species used in traditional medicine in the Andean Altiplano of northern Chile: Clinopodium gilliesii (Benth.) Kuntze [Lamiaceae] (commonly known as Muña-Muña), Mutisia acuminata Ruiz & Pav. var. hirsuta (Meyen) Cabrera [Asteraceae] (commonly known as Chinchircoma), and Tagetes multiflora (Kunth), [Asteraceae] (commonly known as Gracilis), as well as to evaluate their potential inhibitory effects against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). Polyphenolic enriched-extracts (PEEs) of the species were prepared and analyzed and the main components were quantified using HPLC-DAD. In total, 30 phenolic compounds were identified and quantified in all species, including simple phenolics, hydroxycinnamic acids, flavan-3-ols (monomers and polymers), flavanones, and flavonols. In addition, other main phenolics from the extracts were tentatively identified by ESI-MS-MS high-resolution analysis. T. multiflora extract showed the greatest anti-AChE and BChE activity in comparison with C. gilliesii and M. acuminata extracts, being the anti-AChE and BChE activity weak in all extracts in comparison to galantamine control. To comprise to better understand the interactions between cholinesterase enzymes and the main phenolics identified in T. multiflora, molecular docking analysis was conducted.

Acetylcholinesterase inhibition of Alzheimer's disease: identification of potential phytochemicals and designing more effective derivatives to manage disease condition

Alzheimer's disease (AD) is a brain disease characterized by gradual memory loss and cognitive impairments. Acetylcholinesterase (AChE) inhibitors-such as donepezil, memantine, and tacrine-are FDA-approved medications for AD treatment. Due to the lack of their efficacy and higher side effects, many researchers have been searching for effective and safer alternatives. In this study, experimentally proved phytochemicals against brain diseases were screened based on their binding energies to the target site of AChE, pharmacokinetic properties, and drug-likeness. Although some phytochemicals showed higher binding affinities than the control drug (donepezil), they did not show permeability across the blood-brain barrier (BBB). However, berberine, anthocyanin, and diterpene alkaloid can cross the BBB and showed good binding affinities of -10.3, -10.1, and -10.2 kcal/mol, respectively. MD simulation and PCA of the simulation data of the protein and protein-ligand complexes proved that the complexes are stable in the biological environment. A total of 16 derivatives of berberine and 3 derivatives of anthocyanin also showed higher binding energies compared to the binding affinity (-11.5 kcal/mol) of the donepezil. The derivatives were designed by substituting -F, -CF3, -CN, and -NH2, and provided higher docking scores due to increasing of nonbonding interactions. MM/GBSA calculations show that the binding free energies of the best predicted derivatives of diterpene alkaloid, anthocyanin, and berberine (DA22, AC11, and BB40) are -100.4 ± 8.4, -79.3 ± 8.7, and -78.3 ± 10.7 kcal/mol, respectively, with the protein. Overall, this study was successful in finding new, highly effective, and possibly safer inhibitors of AChE.Communicated by Ramaswamy H. Sarma.

3D QSAR based Virtual Screening of Flavonoids as Acetylcholinesterase Inhibitors

In an attempt to develop therapeutic agents to treat Alzheimer's disease, a series of flavonoid analogues were collected, which already had established acetylcholinesterase (AChE) enzyme inhibition activity. For each molecule we also collected biological activity data (Ki). Then, 3D-QSAR (quantitative structure-activity relationship model) was developed which showed acceptable predictive and descriptive capability as represented by standard statistical parameters r2 and q2. This SAR data can explain the key descriptors which can be related to AChE inhibitory activity. Using the QSAR model, pharmacophores were developed based on which, virtual screening was done and a dataset was obtained which loaded as a prediction set to fit the developed QSAR model. Top 10 compounds fitting the QSAR model were subjected to molecular docking. CHEMBL1718051 was found to be the lead compound. This study is offering an example of a computationally-driven tool for prioritisation and discovery of probable AChE inhibitors. Further, in vivo and in vitro testing will show its therapeutic potential.

Exploring the Inhibition of Quercetin on Acetylcholinesterase by Multispectroscopic and In Silico Approaches and Evaluation of Its Neuroprotective Effects on PC12 Cells

This study investigated the inhibitory mechanism of quercetin in acetylcholinesterase (AChE) and its neuroprotective effects on β-amyloid_25-35-induced oxidative stress injury in PC12 cells. Quercetin inhibited AChE in a reversible mixed manner with an IC₅₀ of 4.59 ± 0.27 µM. The binding constant of quercetin with AChE at 25 °C was (5.52 ± 0.05) × 10⁴ L mol^-1. Hydrogen bonding and van der Waals forces were the main interactions in forming the stable quercetin-AChE complex. Computational docking revealed that quercetin was dominant at the peripheral aromatic site in AChE and induced enzymatic allosterism; meanwhile, it extended deep into the active center of AChE and destabilized the hydrogen bond network, which caused the constriction of the gorge entrance and prevented the substrate from entering the enzyme, thus resulting in the inhibition of AChE. Molecular dynamics (MD) simulation emphasized the stability of the quercetin-AChE complex and corroborated the previous findings. Interestingly, a combination of galantamine hydrobromide and quercetin exhibited the synergistic inhibition effect by binding to different active sites of AChE. In a β-amyloid_25-35-induced oxidative stress injury model in PC12 cells, quercetin exerted neuroprotective effects by increasing the glutathione level and reducing the malondialdehyde content and reactive oxygen species levels. These findings may provide novel insights into the development and application of quercetin in the dietary treatment of Alzheimer's disease.

Computer-aided identification of cholinergic and monoaminergic inhibitory flavonoids from Hibiscus sabdariffa L

BACKGROUND

The reduced levels of acetylcholine and dopamine lead to Alzheimer's disease AD and Parkinson disease PD, respectively, due to the action of cholinesterase and monoamine oxidase B.

METHODS

Therapeutic options for AD and PD involve respective cholinergic and monoaminergic inhibitors, and considering the adverse outcomes of cholinergic- and monoaminergic- inhibitory therapeutics, phytoconstituents may be promising alternatives. Reports have shown that different extracts of the calyx of Hibiscus sabdariffa exhibit anticholinesterase and monoamine oxidase B inhibitory properties with potential to delay and prevent the development of AD and PD. However, there is limited knowledge on the multitarget cholinergic and monoaminergic inhibitory activities of individual compounds in this plant. Computational methods were used to identify the specific compounds responsible for the observed cholinergic and monoaminergic inhibitory activities of the H. sabdariffa calyx extracts.

RESULTS

Results confirm that three flavonoids: delphinidin-3-sambubioside, kaempferol-3-O-rutinoside and quercetin-3-rutinoside showed strong binding affinity with acetylcholinesterase, butyrylcholinesterase and monoamine oxidase B while the observed stability of the ligands-enzymes complexes over the MD simulation time suggests their cholinergic and monoaminergic inhibitory properties.

CONCLUSION

The three flavonoids may be responsible for the reported anticholinergic and monoaminergic inhibitory potentials of H. sabdariffa extracts and could be enlisted as multi-target inhibitory agents for cholinesterases and monoamine oxidase B.

Computer Aided Drug Design Methodologies with Natural Products in the Drug Research Against Alzheimer's Disease

Natural products are compounds isolated from plants that provide a variety of lead structures for the development of new drugs by the pharmaceutical industry. The interest in these substances increases because of their beneficial effects on human health. Alzheimer's disease (AD) affects occur in about 80% of individuals aged 65 years. AD, the most common cause of dementia in elderly people, is characterized by progressive neurodegenerative alterations, as decrease of cholinergic impulse, increased toxic effects caused by reactive oxygen species and the inflammatory process that the amyloid plaque participates. In silico studies is relevant in the process of drug discovery; through technological advances in the areas of structural characterization of molecules, computational science and molecular biology have contributed to the planning of new drugs used against neurodegenerative diseases. Considering the social impairment caused by an increased incidence of disease and that there is no chemotherapy treatment effective against AD; several compounds are studied. In the researches for effective neuroprotectants as potential treatments for Alzheimer's disease, natural products have been extensively studied in various AD models. This study aims to carry out a literature review with articles that address the in silico studies of natural products aimed at potential drugs against Alzheimer's disease (AD) in the period from 2015 to 2021.

Potential of flavonoids as anti-Alzheimer's agents: bench to bedside

Developing therapies for neurodegenerative diseases are challenging because of the presence of blood-brain barrier and Alzheimer being one of the commonest and uprising neurodegenerative disorders possess the need for developing novel therapies. Alzheimer's is attributed to be the sixth leading cause of death in the USA and the number of cases is estimated to be increased from 58 million in 2021 to 88 million by 2050. Natural drugs have benefits of being cost-effective, widely available, fewer side effects, and immuno-booster can be useful in managing Alzheimer. Flavonoids can slow the neuronal degeneration as they have shown activity in central nervous system and are able to cross the blood-brain barrier. These can be easily extracted from fruits, vegetable, and plants. In Alzheimer disease, flavonoids scavenges the reactive oxygen species and reduces the production of amyloid beta protein. Agents from sub-classes of flavonoids such as flavanones, flavanols, flavones, flavonols, anthocyanins, and isoflavones having pharmacological action in treating Alzheimer disease are discussed in this review.

An ethnopharmacological review on the therapeutical properties of flavonoids and their mechanisms of actions: A comprehensive review based on up to date knowledge

Flavonoids -a class of low molecular weight secondary metabolites- are ubiquitous and cornucopia throughout the plant kingdom. Structurally, the main structure consists of C6-C3-C6 rings with different substitution patterns so that many sub-classes are obtained, for example: flavonols, flavonolignans, flavonoid glycosides, flavans, anthocyanidins, aurones, anthocyanidins, flavones, neoflavonoids, chalcones, isoflavones, flavones and flavanones. Flavonoids are evaluated to have drug like nature since they possess different therapeutic activities, and can act as cardioprotective, antiviral, antidiabetic, anti-inflammatory, antibacterial, anticancer, and also work against Alzheimer's disease and others. However, information on the relationship between their structure and biological activity is scarce. Therefore, the present review tries to summarize all the therapeutic activities of flavonoids, their mechanisms of action and the structure activity relationship.

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Latest updated ethnopharmacological review of the therapeutic effects of flavonoids.

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Flavonoids are attracting attention because of their therapeutic properties.

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Flavonoids are valuable candidates for drug development against many dangerous diseases.

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This overview summarizes the most important therapeutic effect and mechanism of action of flavonoids.

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General knowledge about the structure activity relationship of flavonoids is summarized.

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Substitution of chemical groups in the structure of flavonoids can significantly change their biological and chemical properties.

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The chemical properties of the basic flavonoid structure should be considered in a drug-based structural program.

In Silico Evaluation Of Some Commercially Available Flavonoids As Galactofuranoyltransferase-2 Inhibitors In The Management Of Tuberculosis

Background:

Background: Galactofuranoyltransferase-2 (GlfT2) enzyme involved in the galactan polymerization of the arabinogalactan (AG) region of the mycolylarabinogalactan-peptidoglycan (mAGP) complex, an important component of the mycobacterial cell wall

Objective:

Objective: With the existing challenge the study focused into identifying certain commercially available flavonoids through molecular docking studies against the Galactofuranoyltransferase-2 enzyme.

Methods:

Methods: The initial pharmacokinetic screening was carried out using Lipinski’s rule of 5 with the help of Molinspiration software. In this perspective, Apigenin, Kaempferol, Rutin, Silibinin and Vitexicarpin were selected for the current study. Except for rutin all other selected flavonoids did not show any violations and thereby selected for the docking studies using AutoDock 4.2.

Results:

Results: The docking results showed that the selected flavonoids have excellent binding energy values between −8.98 to −6.58 kcal/mol against the GlfT2 enzyme. The theoretical inhibition constant was found to be in the range of 260.90 nM to 15.13 µM which coincides with the binding energies of the selected compounds.

Conclusion:

Conclusion: From the selected flavonoids, Silibinin showed excellent binding scores and it has the potential to inhibit the GlfT2 enzyme. Silibinin could act as a novel GlfT2 inhibitor with promising therapeutic activity with low toxicity profile against tuberculosis

Molecular Effects of Pteryxin and Scopoletin in the 5xFAD Alzheimer's Disease Mouse Model

BACKGROUND

Alzheimer's disease (AD) is one of the most prevalent diseases with rapidly increasing numbers, but there is still no medication to treat or stop the disease. Previous data on coumarins suggests that scopoletin may have potential benefits in AD.

OBJECTIVE

Evaluate the therapeutic potential of the coumarins with natural origin - scopoletin and pteryxin in a 5xFAD mouse model of AD Methods: Both compounds were administered at two doses to 12-month-old mice, which represent severe AD pathology. The effects of coumarins were assessed on cognition in mouse experiments. Changes in the overall brain proteome were evaluated using LC-MS/MS analyses.

RESULTS

The Morris water maze test implicated that a higher dose of pteryxin (16 mg/kg) significantly improved learning, and the proteome analysis showed pronounced changes of specific proteins upon pteryxin administration. The amyloid-β precursor protein, glial fibrillary acid protein, and apolipoprotein E protein which are highly associated with AD, were among the differentially expressed proteins at the higher dose of the pteryxin.

CONCLUSION

Overall, pteryxin may be evaluated further as a disease-modifying agent in AD pathology in the late stages of AD.

Biocatalytic modifications of ethynodiol diacetate by fungi, anti-proliferative activity, and acetylcholineterase inhibitory of its transformed products

The fungal transformations of ethynodiol diacetate (1) were investigated for the first-time using Botrytis cinerea, Trichothecium roseum, and R3-2 SP 17. The metabolites obtained are as following: 17α-Ethynyl-17β-acetoxyestr-4-en-3-one-15β-ol (2), 19-nor-17a-ethynyltestosterone (3), and 17α-ethynyl-3β-hydroxy-17β-acetoxyestr-4-ene (4). The new metabolite, 2 (IC50 = 104.8 µM), which has ketone group at C-3, and the β-hydroxyl group at C-15, resulted in an almost equipotent strength with the parent compound (IC50 = 103.3 µM) against proliferation of SH-SY5Y cells. The previously reported biotransformed product, 3, showed almost equal strength to 1 against acetylcholinesterase. Molecular modelling studies were carried out to understand the observed experimental activities, and also to obtain more information on the binding mode and the interactions between the biotransformed products, and enzyme.

Homology modeling, docking, molecular dynamics and in vitro studies to identify Rhipicephalus microplus acetylcholinesterase inhibitors

Rhipicephalus microplus is an important ectoparasite of cattle, causing considerable economical losses. Resistance to chemical acaricides has stimulated the search for new antiparasitic drugs, including natural products as an eco-friendly alternative of control. Flavonoids represent a class of natural compounds with many biological activities, such as enzyme inhibitors. Acetylcholinesterase is an essential enzyme for tick survival that stands out as an important target for the development of acaricides. This work aimed to predict this 3D structure by homology modeling and use the model to identify compound with inhibitory activity. The model of R. microplus AChE1 (RmAChE1) was constructed using MODELLER program. The optimization and molecular dynamic investigation were performed in GROMACS program. The model developed was used, by molecular docking, to evaluate the anticholinesterase activity of flavonoids (quercetin, rutin, diosmin, naringin and hesperidin) and an acaricide synthetic (eserine). Additionally, in vitro inhibition of AChE and larval immersion tests were performed. The model of RmAChE1 showed to be sterically and energetically acceptable. In molecular dynamics simulations, the 3D structure remains stable with Root Mean Square Deviation = 3.58 Å and Root Mean Square Fluctuation = 1.43 Å. In molecular docking analyses, only eserine and quercetin show affinity energy to the RmAChE (Gridscore: -52.17 and -39.44 kcal/mol, respectively). Among the flavonoids, quercetin exhibited the best in vitro inhibition of AChE activity (15.8%) and mortality of larvae tick (30.2%). The use of in silico and in vitro techniques has shown that quercetin showed promising anti-tick activity and structural requirements to interact with RmAChE1. Communicated by Ramaswamy H. Sarma.

Artemisia scoparia and Metabolic Health: Untapped Potential of an Ancient Remedy for Modern Use

Botanicals have a long history of medicinal use for a multitude of ailments, and many modern pharmaceuticals were originally isolated from plants or derived from phytochemicals. Among these, artemisinin, first isolated from Artemisia annua, is the foundation for standard anti-malarial therapies. Plants of the genus Artemisia are among the most common herbal remedies across Asia and Central Europe. The species Artemisia scoparia (SCOPA) is widely used in traditional folk medicine for various liver diseases and inflammatory conditions, as well as for infections, fever, pain, cancer, and diabetes. Modern in vivo and in vitro studies have now investigated SCOPA's effects on these pathologies and its ability to mitigate hepatotoxicity, oxidative stress, obesity, diabetes, and other disease states. This review focuses on the effects of SCOPA that are particularly relevant to metabolic health. Indeed, in recent years, an ethanolic extract of SCOPA has been shown to enhance differentiation of cultured adipocytes and to share some properties of thiazolidinediones (TZDs), a class of insulin-sensitizing agonists of the adipogenic transcription factor PPARγ. In a mouse model of diet-induced obesity, SCOPA diet supplementation lowered fasting insulin and glucose levels, while inducing metabolically favorable changes in adipose tissue and liver. These observations are consistent with many lines of evidence from various tissues and cell types known to contribute to metabolic homeostasis, including immune cells, hepatocytes, and pancreatic beta-cells. Compounds belonging to several classes of phytochemicals have been implicated in these effects, and we provide an overview of these bioactives. The ongoing global epidemics of obesity and metabolic disease clearly require novel therapeutic approaches. While the mechanisms involved in SCOPA's effects on metabolic, anti-inflammatory, and oxidative stress pathways are not fully characterized, current data support further investigation of this plant and its bioactives as potential therapeutic agents in obesity-related metabolic dysfunction and many other conditions.

Combined Structure and Ligand-Based Design of Selective Acetylcholinesterase Inhibitors

Acetylcholinesterase is a prime target for therapeutic intervention in Alzheimer's disease. Acetylcholinesterase inhibitors (AChEIs) are used to improve cognitive abilities, playing therefore an important role in disease management. Drug repurposing screening has been performed on a corporate chemical library containing 11 353 compounds using a target fishing approach comprising three-dimensional (3D) shape similarity and pharmacophore modeling against an approved drug database, Drugbank. This initial screening identified 108 hits. Among them, eight molecules showed structural similarity to the known AChEI drug, pyridostigmine. Further structure-based screening using a pharmacophore-guided rescoring method identifies one more potential hit. Experimental evaluations of the identified hits sieve out a highly selective AChEI scaffold. Further lead optimization using a substructure search approach identifies 24 new potential hits. Three of the 24 compounds (compounds 10b, 10h, and 10i) based on a 6-(2-(pyrrolidin-1-yl)pyrimidin-4-yl)-thiazolo[3,2-a]pyrimidine scaffold showed highly promising AChE inhibition ability with IC₅₀ values of 13.10 ± 0.53, 16.02 ± 0.46, and 6.22 ± 0.54 μM, respectively. Moreover, these compounds are highly selective toward AChE. Compound 10i shows AChE inhibitory activity similar to a known Food and Drug Administration (FDA)-approved drug, galantamine, but with even better selectivity. Interaction analysis reveals that hydrophobic and hydrogen-bonding interactions are the primary driving forces responsible for the observed high affinity of the compound with AChE.

Medroxyprogesterone derivatives from microbial transformation as anti-proliferative agents and acetylcholineterase inhibitors (combined in vitro and in silico approaches)

The fungal transformations of medroxyrogesterone (1) were investigated for the first time using Cunninghamella elegans, Trichothecium roseum, and Mucor plumbeus. The metabolites obtained are as following: 6β, 20-dihydroxymedroxyprogesterone (2), 12β-hydroxymedroxyprogesterone (3), 6β, 11β-dihydroxymedroxyprogesterone (4), 16β-hydroxymedroxyprogesterone (5), 11α, 17-dihydroxy-6α-methylpregn-4-ene-3, 20-dione (6), 11-oxo-medroxyprogesterone (7), 6α-methyl-17α-hydroxypregn-1,4-diene-3,20-dione (8), and 6β-hydroxymedroxyprogesterone (9), 15β-hydroxymedroxyprogesterone (10), 6α-methyl-17α, 11β-dihydroxy-5α-pregnan-3, 20-dione (11), 11β-hydroxymedroxyprogesterone (12), and 11α, 20-dihydroxymedroxyprogesterone (13). Among all the microbial transformed products, the newly isolated biotransformed product 13 showed the most potent activity against proliferation of SH-SY5Y cells. Compounds 12, 5, 6, 9, 11, and 3 (in descending order of activity) also showed some extent of activity against SH-SY5Y tumour cell line. The never been reported biotransformed product, 2, showed the most potent inhibitory activity against acetylcholinesterase. Molecular modelling studies were carried out to understand the observed experimental activities, and also to obtain more information on the binding mode and the interactions between the biotransformed products, and enzyme.

Anti-acetylcholinesterase and toxicity against Artemia salina of chitosan microparticles loaded with essential oils of Cymbopogon flexuosus, Pelargonium x ssp and Copaifera officinalis

Essential oils (EOs) are bioactive compounds with therapeutic potential for use as alternatives or as support to conventional treatments. However, EOs present limitations, such as sensibility to environmental factors, which can be overcome through microencapsulation. The objective of this study was to produce, by spray drying, chitosan microparticles (CMs) loaded with EO of Lemongrass (Cymbopogon flexuosus), Geranium (Pelargonium x ssp) and Copaiba (Copaifera officinalis). Physicochemical and biological characterization of these microparticles showed that CMs presented spherical morphology, had an average size range of 2-3 μm with positive zeta potential (ZP) values, and enhanced thermal stability, compared to free EO. The encapsulation efficiency (EE) ranged from 4.8-58.6%, depending on the oil's properties. In vitro EO release from CMs was determined at different pHs, with 94% release observed in acid media. All microparticles were non-hemolytic at concentrations of up to 0.1 mg·mL^-1. EOs and CMs presented acetylcholinesterase (AChE) inhibition activity (IC 50 ranged from 11.92 to 28.18 μg·mL^-1). Geranium and Copaiba EOs presented higher toxicity against Artemia salina, and greater inhibition of acetylcholinesterase, indicating potential bioactivity for Alzheimer's disease (AD). Our findings demonstrate that CM systems may show promise for the controlled release of these EOs.

Combining In Silico and In Vitro Studies to Evaluate the Acetylcholinesterase Inhibitory Profile of Different Accessions and the Biomarker Triterpenes of Centella asiatica

Alzheimer's disease (AD) is a neurodegenerative disease and the most cause of dementia in elderly adults. Acetylcholinesterase (AChE) is an important beneficial target for AD to control cholinergic signaling deficit. Centella asiatica (CA) has proven to be rich with active ingredients for memory enhancement. In the present study, the chemical profiling of three accession extracts of CA namely SECA-K017, SECA-K018, and, SECA-K019 were performed using high-performance liquid chromatography (HPLC). Four biomarker triterpene compounds were detected in all CA accessions. Quantitative analysis reveals that madecassoside was the highest triterpene in all the CA accessions. The biomarker compounds and the ethanolic extracts of three accessions were investigated for their acetylcholinesterase (AChE) inhibitory activity using Ellman's spectrophotometer method. The inhibitory activity of the triterpenes and accession extracts was compared with the standard AChE inhibitor eserine. The results from the in vitro study showed that the triterpene compounds exhibited an AChE inhibitory activity with the half-maximal inhibitory concentration (IC₅₀) values between 15.05 ± 0.05 and 59.13 ± 0.18 µg/mL. Asiatic acid was found to possess strong AChE inhibitory activity followed by madecassic acid. Among the CA accession extracts, SECA-K017 and SECA-K018 demonstrated a moderate AChE inhibitory activity with an IC₅₀ value of 481.5 ± 0.13 and 763.5 ± 0.16 µg/mL, respectively from the in silico docking studies, it is observed that asiatic acid and madecassic acid showed very good interactions with the active sites and fulfilled docking parameters against AChE. The present study suggested that asiatic acid and madecassic acid in the CA accessions could be responsible for the AChE inhibitory action and could be used as markers to guide further studies on CA as potential natural products for the treatment of AD.

The Additive Effects of Low Dose Intake of Ferulic Acid, Phosphatidylserine and Curcumin, Not Alone, Improve Cognitive Function in APPswe/PS1dE9 Transgenic Mice

Alzheimer's disease (AD) is the most common form of dementia and its prevention and treatment is a worldwide issue. Many natural components considered to be effective against AD have been identified. However, almost all clinical trials of these components for AD reported inconclusive results. We thought that multiple factors such as amyloid β (Aβ) and tau progressed the pathology of AD and that a therapeutic effect would be obtained by using multiple active ingredients with different effects. Thus, in this study, we treated ferulic acid (FA), phosphatidylserine (PS) and curcumin (Cur) in combination or alone to APPswe/PS1dE9 transgenic mice and evaluated cognitive function by Y-maze test. Consequently, only the three-ingredient group exhibited a significant improvement in cognitive function compared to the control group. In addition, we determined the amounts of Aβ, brain-derived neurotrophic factor (BDNF), interleukin (IL)-1β, acetylcholine and phosphorylated tau in the mouse brains after the treatment. In the two-ingredient (FA and PS) group, a significant decrease in IL-1β and an increasing trend in acetylcholine were observed. In the Cur group, significant decreases in Aβ and phosphorylated tau and an increasing trend in BDNF were observed. In the three-ingredient group, all of them were observed. These results indicate that the intake of multiple active ingredients with different mechanisms of action for the prevention and treatment of AD.

Metabolism and pharmacological activities of the natural health-benefiting compound diosmin

Diosmin is a famous natural flavonoid for treating chronic venous insufficiency and varicose veins.

Potential Therapeutic Approaches to Alzheimer's Disease By Bioinformatics, Cheminformatics And Predicted Adme-Tox Tools

BACKGROUND

Alzheimer's disease (AD) is considered a severe, irreversible and progressive neurodegenerative disorder. Currently, the pharmacological management of AD is based on a few clinically approved acethylcholinesterase (AChE) and N-methyl-D-aspartate (NMDA) receptor ligands, with unclear molecular mechanisms and severe side effects.

METHODS

Here, we reviewed the most recent bioinformatics, cheminformatics (SAR, drug design, molecular docking, friendly databases, ADME-Tox) and experimental data on relevant structurebiological activity relationships and molecular mechanisms of some natural and synthetic compounds with possible anti-AD effects (inhibitors of AChE, NMDA receptors, beta-secretase, amyloid beta (Aβ), redox metals) or acting on multiple AD targets at once. We considered: (i) in silico supported by experimental studies regarding the pharmacological potential of natural compounds as resveratrol, natural alkaloids, flavonoids isolated from various plants and donepezil, galantamine, rivastagmine and memantine derivatives, (ii) the most important pharmacokinetic descriptors of natural compounds in comparison with donepezil, memantine and galantamine.

RESULTS

In silico and experimental methods applied to synthetic compounds led to the identification of new AChE inhibitors, NMDA antagonists, multipotent hybrids targeting different AD processes and metal-organic compounds acting as Aβ inhibitors. Natural compounds appear as multipotent agents, acting on several AD pathways: cholinesterases, NMDA receptors, secretases or Aβ, but their efficiency in vivo and their correct dosage should be determined.

CONCLUSION

Bioinformatics, cheminformatics and ADME-Tox methods can be very helpful in the quest for an effective anti-AD treatment, allowing the identification of novel drugs, enhancing the druggability of molecular targets and providing a deeper understanding of AD pathological mechanisms.

Dietary Polyphenols: A Multifactorial Strategy to Target Alzheimer's Disease

Ageing is an inevitable fundamental process for people and is their greatest risk factor for neurodegenerative disease. The ageing processes bring changes in cells that can drive the organisms to experience loss of nutrient sensing, disrupted cellular functions, increased oxidative stress, loss of cellular homeostasis, genomic instability, accumulation of misfolded protein, impaired cellular defenses and telomere shortening. Perturbation of these vital cellular processes in neuronal cells can lead to life threatening neurological disorders like Alzheimer's Disease, Parkinson's Disease, Huntington's Disease, Lewy body dementia, etc. Alzheimer's Disease is the most frequent cause of deaths in the elderly population. Various therapeutic molecules have been designed to overcome the social, economic and health care burden caused by Alzheimer's Disease. Almost all the chemical compounds in clinical practice have been found to treat symptoms only limiting them to palliative care. The reason behind such imperfect drugs may result from the inefficiencies of the current drugs to target the cause of the disease. Here, we review the potential role of antioxidant polyphenolic compounds that could possibly be the most effective preventative strategy against Alzheimer's Disease.

Studies of the Anti-amnesic Effects and Mechanisms of Single and Combined Use of Donepezil and Ginkgo Ketoester Tablet on Scopolamine-Induced Memory Impairment in Mice

Ginkgo ketoester tablets (GT) and donepezil were a clinically used combination for the treatment of Alzheimer's disease (AD). The aim of the study was undertaken to investigate the antiamnesic effects of the two drugs alone and in combination through in vivo models of the Morris water maze along with in vitro antioxidants, acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). The potential mechanisms were speculated by the activities of acetylcholine (ACh), AChE, superoxide dismutase (SOD), and malondialdehyde (MDA) and the protein expression of brain-derived neurotrophic factor (BDNF) and tyrosine protein kinase B (TrkB). The combination group showed a concentration-dependent inhibition of cholinesterase and antioxidation. As far as its mechanism was concerned, the combination of two drugs exerted excellent effects on oxidative stress, cholinergic pathway damage, and inactivation of the BDNF-TrkB signaling pathway. Additionally, to elucidate the binding mechanism of GT active ingredients into the structure of AChE, the results of molecular docking studies indicated that hydrogen and/or hydrophobic bonds might play an important role in their binding process. Thus, the combination of drugs could treat AD perfectly and further verify the scientific rationality of clinical medication.

Flavonoids as acetylcholinesterase inhibitors: Current therapeutic standing and future prospects

BACKGROUND

Acetylcholinesterase (AChE), a serine hydrolase, is primarily responsible for the termination of signal transmission in the cholinergic system, owing to its outstanding hydrolyzing potential. Its substrate acetylcholine (ACh), is a neurotransmitter of the cholinergic system, with a predominant effect on motor neurons involved in memory formation. So, by decreasing the activity of this enzyme by employment of specific inhibitors, a number of motor neuron disorders such as myasthenia gravis, glaucoma, Lewy body dementia, and Alzheimer's disease, among others, can be treated. However, the current-available AChE inhibitors have several limitations in terms of efficacy, therapeutic range, and safety.

SCOPE AND APPROACH

Primarily due to the non-compliance of current therapies, new, effective and safe inhibitors are being searched for, especially those which act through multiple receptor sites, but do not elicit undesirable effects. In this regard, the evaluation of phytochemicals such as flavonoids, can be a rational approach. The therapeutic potential of flavonoids has already been recognized agaisnt several ailments. This review deals with various plant-derived flavonoids, their preclinical potential as AChE inhibitors, in established assays, possible mechanisms of action, and structural activity relationship (SAR).

RESULTS AND CONCLUSIONS

Subsequently, a number of plant-derived flavonoids with outstanding efficacy and potency as AChE inhibitors, the mechanistic, their safety profiles, and pharmacokinetic attributes have been discussed. Through derivatization of these reported flavonoids, some limitation in efficacy or pharmacokinetic parameters can be addressed. The selected flavonoids ought to be tested in clinical studies to discover new neuro-therapeutic candidates.

Molecular modeling and in vitro approaches towards cholinesterase inhibitory effect of some natural xanthohumol, naringenin, and acyl phloroglucinol derivatives

BACKGROUND

Many natural products, particularly phenolic compounds, have been reported to have a strong inhibition against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), the key enzymes in the pathology of Alzheimer's disease (AD).

HYPOTHESIS

Therefore, we hypothesized that some xanthahumol, naringenin, and acyl phloroglucinol derivatives (1-14) isolated from Humulus lupulus L. (hops) may have an inhibitory potential against AChE and BChE.

METHODS

Inhibitory potential of compounds 1-14 were tested against AChE and BChE using ELISA microtiter assay. Different molecular docking simulations, including IFD and GOLD protocols, were implemented to verify the interactions between the ligands and the active site amino acids and also their binding energies inside the catalytic crevices of AChE and BChE. ADME/Tox analysis were used to determine pharmacological activities of the compounds.

RESULTS

Among them, 3‑hydroxy‑xanthohumol (IC₅₀ = 51.25 ± 0.88 µM) and xanthohumol (IC₅₀ = 71.34 ± 2.09 µM), displayed a moderate AChE inhibition in comparison to that of the reference (galanthamine, IC₅₀ = 2.52 ± 0.15 µM). In addition to 3‑hydroxy‑xanthohumol (IC₅₀ = 63.07 ± 3.76 µM) and xanthohumol (IC₅₀ = 32.67 ± 2.82 µM), 8-prenylnaringenin (IC₅₀ = 86.58 ± 3.74 µM) also showed micromolar-range inhibition against BChE (galanthamine, IC₅₀ = 46.58 ± 0.91 µM). Rest of the compounds were found to be either inactive or having inhibition below 50%. Prediction of pharmacokinetic studies suggested that all the ligands revealed acceptable drug-like profiles. Docking simulations demonstrate not only the prediction of ligand binding energies of the compounds inside the catalytic domains of the targets, but also highlight the critical amino acids contributing to stabilizations of the ligands.

CONCLUSION

Our findings revealed that xanthohumol in particular could be considered as lead molecule to explore new cholinesterase inhibitors for AD.

The cytochrome c–cyclo[6]aramide complex as a supramolecular catalyst in methanol

A hydrogen-bonded aromatic amide macrocycle forms a host–guest complex with cytochrome c, which acts as a supramolecular catalyst for the oxidation of benzhydrol even at low temperatures.

Study on the Anticoagulant or Procoagulant Activities of Type II Phenolic Acid Derivatives

In this study, three type II phenolic acids (caffeic acid, p-hydroxycinnamic acid, and ferulic acid) were used to synthesize a total of 18 phenolic acid derivatives. With molecular docking for molecule design and target protein (factors) screening, in combination with the confirmation of target proteins (factors) by surface plasmon resonance, and the evaluation of haemostatic and anticoagulant activities with five blood assays (plasma recalcification time, prothrombin time, activated partial thromboplastin time, fibrinogen, and thrombin time), the data indicated that caffeic acid derivatives showed certain anticoagulant or procoagulant activities and that two other series contained compounds with the best anticoagulant activities. Using Materials Studio analysis, particular functional groups that affect anticoagulant or procoagulant activities were revealed, and these conclusions can guide the discovery of compounds with better activities.