Linarin improves the dyskinesia recovery in Alzheimer's disease zebrafish by inhibiting the acetylcholinesterase activity

Aluminum chloride and D-galactose induced a zebrafish model of Alzheimer's disease with cognitive deficits and aging

Alzheimer's disease (AD) is an age-related neurodegenerative disorder. Transgenic and pharmacological AD models are extensively studied to understand AD mechanisms and drug discovery. However, they are time-consuming and relatively costly, which hinders the discovery of potential anti-AD therapeutics. Here, we established a new model of AD in larval zebrafish by co-treatment with aluminum chloride (AlCl3) and D-galactose (D-gal) for 72 h. In particular, exposure to 150 μM AlCl3 + 40 mg/mL D-gal, 200 μM AlCl3 + 30 mg/mL D-gal, or 200 μM AlCl3 + 40 mg/mL D-gal successfully induced AD-like symptoms and aging features. Co-treatment with AlCl3 and D-gal caused significant learning and memory deficits, as well as impaired response ability and locomotor capacity in the plus-maze and light/dark test. Moreover, increased acetylcholinesterase and β-galactosidase activities, β-amyloid 1-42 deposition, reduced telomerase activity, elevated interleukin 1 beta mRNA expression, and enhanced reactive oxygen species production were also observed. In conclusion, our zebrafish model is simple, rapid, effective and affordable, incorporating key features of AD and aging, thus may become a unique and powerful tool for high-throughput screening of anti-AD compounds in vivo.

An efficient flavonoid glycosyltransferase NjUGT73B1 from Nardostachys jatamansi of alpine Himalayas discovered by structure-based protein clustering

Tilianin and linarin, two rare glycosylated flavonoids in the aromatic endangered medicinal plant Nardostachys jatamansi (D.on)DC., play an important role in the fields of medicine, cosmetics, food and dye industries. However, there remains a lack of comprehensive understanding regarding their biosynthetic pathway. In this study, the phytochemical investigation of N. jatamansi resulted in the isolation of linarin. With help of AlphaFold2 to cluster the entire glycosyltransferase family based on predicted structure similarities, we successfully identified a flavonoid glycosyltransferase NjUGT73B1, which could efficiently catalyze the glucosylation of acacetin at 7-OH to produce tilianin, also the key precursor in the biosynthesis of linarin. Additionally, NjUGT73B1 displayed a high degree of substrate promiscuity, enabling glucosylation at 7-OH of many flavonoids. Molecular modeling and site-directed mutagenesis revealed that H19, H21, H370, F126, and F127 play the crucial roles in the glycosylation ability of NjUGT73B1. Notably, comparation with the wild NjUGT73B1, mutant H19K led to a 50% increase in the activity of producing tilianin from acacetin.

Three dimensional and four dimensional live imaging to study mechanisms of progressive neurodegeneration

Neurodegenerative diseases are complex and progressive, posing challenges to their study and understanding. Recent advances in microscopy imaging technologies have enabled the exploration of neurons in three spatial dimensions (3D) over time (4D). When applied to 3D cultures, tissues, or animals, these technologies can provide valuable insights into the dynamic and spatial nature of neurodegenerative diseases. This review focuses on the use of imaging techniques and neurodegenerative disease models to study neurodegeneration in 4D. Imaging techniques such as confocal microscopy, two-photon microscopy, miniscope imaging, light sheet microscopy, and robotic microscopy offer powerful tools to visualize and analyze neuronal changes over time in 3D tissue. Application of these technologies to in vitro models of neurodegeneration such as mouse organotypic culture systems and human organoid models provide versatile platforms to study neurodegeneration in a physiologically relevant context. Additionally, use of 4D imaging in vivo, including in mouse and zebrafish models of neurodegenerative diseases, allows for the investigation of early dysfunction and behavioral changes associated with neurodegeneration. We propose that these studies have the power to overcome the limitations of two-dimensional monolayer neuronal cultures and pave the way for improved understanding of the dynamics of neurodegenerative diseases and the development of effective therapeutic strategies.

Enhanced antichemobrain activity of amino acid assisted ferulic acid solid dispersion in adult zebrafish (Danio rerio)

Chemotherapy-induced cognitive impairment (CICI), also known as "chemobrain," is a common side effect of breast cancer therapy which causes oxidative stress and generation of reactive oxygen species (ROS). Ferulic acid (FA), a natural polyphenol, belongs to BCS class II is confirmed to have nootropic, neuroprotective and antioxidant effects. Here, we have developed FA solid dispersion (SD) in order to enhance its therapeutic potential against chemobrain. An amorphous ferulic acid loaded leucin solid dispersion (FA-Leu SD) was prepared by utilizing amino acid through spray-drying technique. The solid-state characterization was carried out via Fourier-transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), X-ray diffraction (XRD), and field emission scanning electron microscopy (FE-SEM). Additionally, in-vitro release studies and antioxidant assay were also performed along with in-vivo locomotor, biochemical and histopathological analysis. The physical properties showed that FA-Leu SD so formed exhibited spherical, irregular surface hollow cavity of along with broad melting endotherm as observed from FE-SEM and DSC results. The XRD spectra demonstrated absence of sharp and intense peaks in FA-Leu SD which evidenced for complete encapsulation of drug into carrier. Moreover, in-vitro drug release studies over a period of 5 h in PBS (pH 7.4) displayed a significant enhanced release in the first hr (68. 49 ± 5.39%) and in-vitro DPPH assay displayed greater antioxidant potential of FA in FA-Leu SD. Furthermore, the in-vivo behavioral findings of FA-Leu SD (equivalent to 150 mg/kg of free FA) exhibited positive results accompanied by in-vivo biochemical and molecular TNF-α showed a significant difference (p < 0.001) vis-à-vis DOX treated group upon DOX + FA-Leu SD. Additionally, histopathological analysis revealed neuroprotective effects of FA-Leu SD together with declined oxidative stress due to antioxidant potential of FA which was induced by anticancer drug doxorubicin (DOX). Overall, the above findings concluded that spray-dried FA-Leu SD could be useful for the treatment of chemotherapy induced cognitive impairment.

Linarin ameliorates ischemia-reperfusion injury by the inhibition of endoplasmic reticulum stress targeting AKR1B1

Due to various factors, there is still a lack of effective neuroprotective agents for ischemic stroke in clinical practice. Neuroinflammation and neuronal apoptosis mediated by endoplasmic reticulum stress are some of the important pathological mechanisms in ischemic stroke. Linarin has been reported to have anti-inflammation, antioxidant, and anti-apoptotic effects in myocardial ischemia, osteoarthritis, and kidney disease. Whether it exerts neuroprotective functions in ischemic stroke has not been investigated. The results showed that linarin could reduce the infarct volume in cerebral ischemia animal models, improve the neurological function scores and suppress the expression of inflammatory factors mediating the NF-κB. Meanwhile, it could protect the neurons from OGD/R-induced-apoptosis, which was related to the PERK-eIF2α pathway. Our results suggested linarin could inhibit neuronal inflammation and apoptosis induced by endoplasmic reticulum stress. Furthermore, the neuroprotective effect of linarin may be related to the inhibition of AKR1B1. Our study offers new insight into protecting against ischemia-reperfusion injury by linarin treatment in stroke.

Neuroprotective effect of plasmalogens on AlCl3-induced Alzheimer's disease zebrafish via acting on the regulatory network of ferroptosis, apoptosis and synaptic neurotransmission release with oxidative stress as the center

Plasmalogens (Pls) are considered to play a potential role in the treatment of neurodegenerative diseases. In the present study, an Alzheimer's disease (AD) model of zebrafish induced by AlCl3 was established to investigate whether the marine-derived Pls could alleviate cognitive impairments of AD zebrafish. Behavioral tests were carried out to assess the athletic ability. The transcriptional profiles of zebrafish in the control, AD model and AD_PLS group were compared and analyzed to determine the potential mechanisms of dietary Pls on AD. The study found that Pls could reverse athletic impairment in the AD zebrafish model, and the expression levels of genes related to ferroptosis, synaptic dysfunction and apoptosis were significantly altered between experimental groups. Further analysis showed that all of these genes were associated with oxidative stress (OS). These data suggest that healthy protective role of marine-derived Pls on AD zebrafish may result from inhibition of ferroptosis and neuronal apoptosis, restoring synaptic neurotransmission release, and reducing neuroinflammation. Among them, Oxidative stress is acted as the center to connect different regulation pathways. This study provides evidence to support the essential roles of OS in pathogenesis of AD, and the application of Pls in relieving AD.

Citronellal as a Promising Candidate for Alzheimer's Disease Treatment: A Comprehensive Study on In Silico and In Vivo Anti-Acetylcholine Esterase Activity

One of the primary therapeutic approaches for managing Alzheimer's disease (AD) involves the modulation of Acetylcholine esterase (AChE) activity to elevate acetylcholine (ACh) levels inside the brain. The current study employed computational chemistry approaches to evaluate the inhibitory effects of CTN on AChE. The docking results showed that Citronellal (CTN) and standard Donepezil (DON) have a binding affinity of -6.5 and -9.2 Kcal/mol, respectively, towards AChE. Further studies using molecular dynamics (MD) simulations were carried out on these two compounds. Binding free energy calculations and ligand-protein binding patterns suggested that CTN has a binding affinity of -12.2078. In contrast, DON has a much stronger binding relationship of -47.9969, indicating that the standard DON has a much higher binding affinity than CTN for AChE. In an in vivo study, Alzheimer-type dementia was induced in mice by scopolamine (1.5 mg/kg/day i.p) for 14 days. CTN was administered (25 and 50 mg/kg. i.p) along with scopolamine (SCO) administration. DON (0.5 mg/kg orally) was used as a reference drug. CTN administration significantly improved the mice's behavior as evaluated by the Morris water maze test, evident from decreased escape latency to 65.4%, and in the CPS test, apparent from reduced escape latency to 69.8% compared to the positive control mice. Moreover, CTN significantly increased the activities of antioxidant enzymes such as catalase and superoxide dismutase (SOD) compared to SCO. Furthermore, CTN administration significantly decreased SCO-induced elevated AChE levels in mice. These results were supported by histopathological and in silico molecular docking studies. CTN may be a potential antioxidant and neuroprotective supplement.

Zebrafish: A Model Deciphering the Impact of Flavonoids on Neurodegenerative Disorders

Over the past century, advances in biotechnology, biochemistry, and pharmacognosy have spotlighted flavonoids, polyphenolic secondary metabolites that have the ability to modulate many pathways involved in various biological mechanisms, including those involved in neuronal plasticity, learning, and memory. Moreover, flavonoids are known to impact the biological processes involved in developing neurodegenerative diseases, namely oxidative stress, neuroinflammation, and mitochondrial dysfunction. Thus, several flavonoids could be used as adjuvants to prevent and counteract neurodegenerative disorders such as Alzheimer's and Parkinson's diseases. Zebrafish is an interesting model organism that can offer new opportunities to study the beneficial effects of flavonoids on neurodegenerative diseases. Indeed, the high genome homology of 70% to humans, the brain organization largely similar to the human brain as well as the similar neuroanatomical and neurochemical processes, and the high neurogenic activity maintained in the adult brain makes zebrafish a valuable model for the study of human neurodegenerative diseases and deciphering the impact of flavonoids on those disorders.

Kaempferol as a potential neuroprotector in Alzheimer's disease

Alzheimer's disease (AD), the most prevalent neurodegenerative disorder, is largely associated with cognitive disability, amnesia, and abnormal behavior, which accounts for about two third of people with dementia worldwide. A growing body of research demonstrates that AD is connected to several factors, such as aberrant accumulation of amyloid-beta (Aβ), increase in the hyperphosphorylation of Tau protein, and the formation of neurofibrillary tangles, mitochondrial dysfunction, and inordinate production of reactive oxygen species (ROS). Despite remarkable efforts to realize the etiology and pathophysiology of AD, until now, scientists have not developed and introduced medications that can permanently cease the progression of AD. Thus, nowadays, research on the role of natural products in the treatment and prevention of AD has attracted great attention. Kaempferol (KMP), one of the prominent members of flavonols, exerts its ameliorative actions via attenuating oxidative stress and inflammation, reducing Aβ-induced neurotoxicity, and regulating the cholinergic system. Therefore, in this review article, we outlined the possible effects of KMP in the prevention and treatment of AD. PRACTICAL APPLICATIONS: Kaempferol (KMP) exerts its ameliorative actions against AD via attenuating oxidative stress and inflammation, reducing Aβ-induced neurotoxicity, and regulating the cholinergic system. The beneficial effects of KMP were addressed in both in vitro and in vivo studies; however, conducting further research can warrant its long-term effects as a safe agent. Therefore, after confirming its favorable functions in the prevention and treatment of AD, it could be used as a safe and effective agent.

Aaptamine - a dual acetyl - and butyrylcholinesterase inhibitor as potential anti-Alzheimer's disease agent

CONTEXT

Alzheimer's disease (AD) is a neurodegenerative disorder that affects millions of people worldwide. Acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) are promising therapeutic targets for AD.

OBJECTIVE

To evaluate the inhibitory effects of aaptamine on two cholinesterases and investigate the in vivo therapeutic effect on AD in a zebrafish model.

MATERIALS AND METHODS

Aaptamine was isolated from the sponge Aaptos suberitoides Brøndsted (Suberitidae). Enzyme inhibition, kinetic analysis, surface plasmon resonance (SPR) and molecular docking assays were used to determine its inhibitory effect on AChE and BuChE in vitro. Zebrafish were divided into six groups: control, model, 8 μM donepezil, 5 , 10  and 20 μM aaptamine. After three days of drug treatment, the behaviour assay was performed.

RESULTS

The IC₅₀ values of aaptamine towards AChE and BuChE were 16.0 and 4.6 μM. And aaptamine directly inhibited the two cholinesterases in the mixed inhibition type, with K_i values of 6.96 ± 0.04 and 6.35 ± 0.02 μM, with K_d values of 87.6 and 10.7 μM. Besides, aaptamine interacts with the crucial anionic sites of AChE and BuChE. In vivo studies indicated that the dyskinesia recovery rates of 5 , 10  and 20 μM aaptamine group were 34.8, 58.8 and 60.0%, respectively, and that of donepezil was 63.7%.

DISCUSSION AND CONCLUSIONS

Aaptamine showed great potential to exert its anti-AD effects by directly inhibiting the activities of AChE and BuChE. Therefore, this study identified a novel medicinal application of aaptamine and provided a new structural scaffold for the development of anti-AD drugs.

Progress in the development of naturally derived active metabolites-based drugs: Potential therapeutics for Alzheimer's disease

Alzheimer's disease (AD) is an extensive age-associated neurodegenerative disorder. In spite of wide-ranging progress in understanding the AD pathology for the past 50 years, clinical trials based on the hypothesis of amyloid-beta (Aβ) have reserved worsening particularly at late-stage human trials. Consequently, very few old drugs are presently used for AD with inadequate clinical consequences and various side effects. We focus on widespread pharmacological and beneficial principles for existing as well as future drugs. Multitargeting approaches by means of general antioxidant and anti-inflammatory mechanisms allied with particular receptor and/or enzyme-mediated actions in neuroprotection and neurodegeneration. The plant kingdom comprises a vast range of species with an incredible diversity of bioactive metabolites with diverse chemical scaffolds. In recent times, an increasing body of facts recommended the use of phytochemicals to decelerate AD's onset and progression. The definitive goal of AD investigation is to avert the onset of neurodegeneration, thereby allowing successful aging devoid of cognitive decline. At this point, we discussed the neurological protective role of natural products and naturally derived therapeutic agents for AD from various natural polyphenolic compounds and medicinal plants. In conclusion, medicinal plants act as a chief source of different bioactive constituents.

Protective Effects of Flavonoids against Alzheimer's Disease: Pathological Hypothesis, Potential Targets, and Structure-Activity Relationship

Alzheimer’s disease (AD) is a neurodegenerative disease with high morbidity and mortality, for which there is no available cure. Currently, it is generally believed that AD is a disease caused by multiple factors, such as amyloid-beta accumulation, tau protein hyperphosphorylation, oxidative stress, and inflammation. Multitarget prevention and treatment strategies for AD are recommended. Interestingly, naturally occurring dietary flavonoids, a class of polyphenols, have been reported to have multiple biological activities and anti-AD effects in several AD models owing to their antioxidative, anti-inflammatory, and anti-amyloidogenic properties. In this review, we summarize and discuss the existing multiple pathogenic factors of AD. Moreover, we further elaborate on the biological activities of natural flavonoids and their potential mode of action and targets in managing AD by presenting a wide range of experimental evidence. The gathered data indicate that flavonoids can be regarded as prophylactics to slow the advancement of AD or avert its onset. Different flavonoids have different activities and varying levels of activity. Further, this review summarizes the structure–activity relationship of flavonoids based on the existing literature and can provide guidance on the design and selection of flavonoids as anti-AD drugs.

A Linarin Derivative Protects against Ischemia-Induced Neuronal Injury in Mice by Promoting Cerebral Blood Flow Recovery via KDELR-Dependent CSPG4 Activation

The cerebral ischemic microvascular response and collateral circulation compensatory capacity are important for the outcome of ischemic stroke. Here, we sought to evaluate the effect of a linarin derivate 4′-benzylapigenin-7-β-rutinoside (BLR) on neurological function and cerebral blood flow restoration in ischemic stroke. A mouse model of middle cerebral artery occlusion (30 min) with reperfusion (24 h) was used to mimic ischemic stroke in vivo, and 2,3,5-triphenyltetrazolium chloride (TTC) staining, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assays, and immunofluorescence microscopy were used to assess the protective effects of BLR on infarct volume, neurological function, neuronal apoptosis, and inflammatory damage. Cerebral blood flow was assayed by laser speckle contrast imaging. Double immunostaining of GFAP-collagen IV and brain lucidification were performed to determine the protective effects of BLR on the disruption of brain vasculature. Differential gene expression was assessed by RNA sequencing. Coimmunoprecipitation and western blotting were used to explore the mechanism of BLR-induced neuroprotection. The results of in vivo experiments showed that BLR administration after reperfusion onset reduced infarct volume, improved neurological function, and decreased the neural cell apoptosis and inflammatory response in the ischemic brain, which was accompanied by increased cerebral blood flow and reduced detachment of astrocyte endfeet from the capillary basement membrane. The RNA sequencing data showed that BLR promoted the upregulation of extracellular matrix and angiogenesis pathway-related genes; in particular, BLR significantly increased the expression of the chondroitin sulfate proteoglycan 4 (CSPG4) gene, enhanced the membrane location of CSPG4, and promoted its downstream signaling protein expression, which is associated with KDEL receptor (KDELR) activation. In addition, activated KDELR further increased the phosphorylation of mitogen-activated protein kinases after BLR treatment. Taken together, our data showed that BLR could protect against ischemic brain injury and may serve as a new promising therapeutic candidate drug for ischemic stroke, and that KDELR might act as both a sensor and effector to activate CSPG4 to increase cerebral blood flow.

A review of the ethnomedicinal uses, chemistry, and pharmacological properties of the genus Acanthus (Acanthaceae)

ETHNOPHARMACOLOGICAL RELEVANCE

The Acanthus genus belongs to the Acanthaceae family, and its species are distributed in all continents, mainly in tropical and subtropical regions. Several traditional applications are referred to, but few scientific studies validate them. Despite this, studies in animal models corroborate some of its uses in folk medicine, such as anticancer, antidiabetic, anti-inflammatory, and antinociceptive, which encourages the research on plants of this genus.

AIM OF THE REVIEW

To our knowledge, this document is the first comprehensive review study that provides information on the geographic distribution, botanical characteristics, ethnomedicinal uses, phytochemicals, and pharmacological activities of some Acanthus species to understand the correlation between traditional uses, phytochemical, and pharmacological activities, providing perspectives for future studies.

RESULTS

In traditional medicine, Acanthus species are mainly used for diseases of respiratory, nervous and reproductive system, gastrointestinal and urinary tract, and skin illness. The most used species are A. montanus, A. ilicifolius, and A. ebracteatus. Chemical compounds (125) from different chemical classes were isolated and identified in seven species, mainly from A. ilicifolius, about 80, followed by A. ebracteatus and A. montanus, appearing with a slightly lower number with fewer phytochemical profile studies. Isolated phytoconstituents have been mainly alkaloids, phenylpropanoid glycosides, and phenylethanoids. In addition, aliphatic glycosides, flavonoids, lignan glycosides, megastigmane derivatives, triterpenoids, steroids, fatty acids, alcohols, hydroxybenzoic acids, simple phenols were also cited. Scientific studies from Acanthus species extracts and their phytoconstituents support their ethnomedical uses. Antimicrobial activity that is the most studied, followed by the antioxidant, anti-inflammatory, and anticancer properties, underlie many Acanthus species activities. A. dioscoridis, A. ebracteatus, A. hirsutus, A. ilicifolius, A. mollis, A. montanus, and A. polystachyus have studies on these activities, A. ilicifolius being the one with the most publications. Most studies were essentially performed in vitro. However, the anticancer, antidiabetic, anti-inflammatory and antinociceptive properties have been studied in vivo.

CONCLUSION

Acanthus species have remarkable phytoconstituents with different biological activities, such as antioxidant, antimicrobial, anti-inflammatory, antinociceptive, hepatoprotective, and leishmanicidal, supporting traditional uses of some species. However, many others remain unexplored. Future studies should focus on these species, especially pharmacological properties, toxicity, and action mechanisms. This review provides a comprehensive report on Acanthus genus plants, evidencing their therapeutic potential and prospects for discovering new safe and effective drugs from Acanthus species.

AlCl3 induced learning and memory deficit in zebrafish

Aluminium is a metal known to cause neurotoxicity in the brain, by promoting neurodegeneration and affecting memory and cognitive ability. AlCl₃ has been reported to enhance reactive oxygen species (ROS) and inflammatory markers which are further responsible for the degeneration of neurons. AlCl₃ exposure to zebrafish causes behavioral, biochemical, and neurochemical changes in the brain. In our study, Zebrafish were exposed to AlCl₃ at three different doses (50 µg/L, 100 µg/L, and 200 µg/L) for four consecutive days. On days 1st and 4th, a novel diving test was performed to check anxiety in zebrafish. T - maze and novel object recognition test were used to check the memory on days 3rd and 4th with the help of ANY-maze software. On the last day (4th day), zebrafishes were sacrificed and whole brains were used to perform the biochemical, neurotransmitters, histopathological, and immunohistochemistry analysis. Our study revealed that AlCl₃ exposure significantly decreased the total distance traveled, and the number of entries in the top zone and increased the time spent in the bottom zone, checked through the novel diving test. In the T maze test, AlCl₃ treated zebrafish showed significantly increased transfer latency to the favorable zone and time spent, and the number of entries to the unfavorable zone. The exploration time with the novel object was reduced significantly after AlCl₃ treatment. Moreover, reduced glutathione (GSH) and superoxide dismutase (SOD) levels were significantly reduced in AlCl₃ treated zebrafish whereas malondialdehyde (MDA) level was found to be increased, indicating high oxidative stress. The neurotransmitters level was also disturbed indicated by the significantly decreased GABA, dopamine, noradrenaline, and Serotonin levels and increased glutamate level in the brain of zebrafish treated with AlCl₃. Moreover, histopathological and immunohistochemistry study shows a markedly increased number of pyknotic neurons and reduced the expression of Nrf2 in the zebrafish brain after AlCl₃ exposure. These findings suggest that AlCl₃ significantly causes behavioral, biochemical, neurotransmitters, morphological, and molecular changes in zebrafish, ultimately causing AD.

Eucommia ulmoides Olive Male Flower Extracts Ameliorate Alzheimer's Disease-Like Pathology in Zebrafish via Regulating Autophagy, Acetylcholinesterase, and the Dopamine Transporter

Alzheimer's disease (AD) is the most prevalent neural disorder. However, the therapeutic agents for AD are limited. Eucommia ulmoides Olive (EUO) is widely used as a traditional Chinese herb to treat various neurodegenerative disorders. Therefore, we investigated whether the extracts of EUO male flower (EUMF) have therapeutic effects against AD. We focused on the flavonoids of EUMF and identified the composition using a targeted HPLC-MS analysis. As a result, 125 flavonoids and flavanols, 32 flavanones, 22 isoflavonoids, 11 chalcones and dihydrochalcones, and 17 anthocyanins were identified. Then, the anti-AD effects of the EUMF were tested by using zebrafish AD model. The behavioral changes were detected by automated video-tracking system. Aβ deposition was assayed by thioflavin S staining. Ache activity and cell apoptosis in zebrafish were tested by, Acetylcholine Assay Kit and TUNEL assay, respectively. The results showed that EUMF significantly rescued the dyskinesia of zebrafish and inhibited Aβ deposition, Ache activity, and occurrence of cell apoptosis in the head of zebrafish induced by AlCl₃. We also investigated the mechanism underlying anti-AD effects of EUMF by RT-qPCR and found that EUMF ameliorated AD-like symptoms possibly through inhibiting excessive autophagy and the abnormal expressions of ache and slc6a3 genes. In summary, our findings suggested EUMF can be a therapeutic candidate for AD treatment.

The Brilliance of the Zebrafish Model: Perception on Behavior and Alzheimer’s Disease

Alzheimer’s disease (AD) has become increasingly prevalent in the elderly population across the world. It’s pathophysiological markers such as overproduction along with the accumulation of amyloid beta (Aβ) plaques and neurofibrillary tangles (NFT) are posing a serious challenge to novel drug development processes. A model which simulates the human neurodegenerative mechanism will be beneficial for rapid screening of potential drug candidates. Due to the comparable neurological network with humans, zebrafish has emerged as a promising AD model. This model has been thoroughly validated through research in aspects of neuronal pathways analogous to the human brain. The cholinergic, glutamatergic, and GABAergic pathways, which play a role in the manifested behavior of the zebrafish, are well defined. There are several behavioral models in both adult zebrafish and larvae to establish various aspects of cognitive impairment including spatial memory, associative memory, anxiety, and other such features that are manifested in AD. The zebrafish model eliminates the shortcomings of previously recognized mammalian models, in terms of expense, extensive assessment durations, and the complexity of imaging the brain to test the efficacy of therapeutic interventions. This review highlights the various models that analyze the changes in the normal behavioral patterns of the zebrafish when exposed to AD inducing agents. The mechanistic pathway adopted by drugs and novel therapeutic strategies can be explored via these behavioral models and their efficacy to slow the progression of AD can be evaluated.

Phlorizin alleviates cholinergic memory impairment and regulates gut microbiota in d-galactose induced mice

We explored the effect of phlorizin against cholinergic memory impairment and dysbacteriosis in D-galactose induced ICR mice. The control (CON) group, D-galactose model (DGM) group, and three groups (DG-PL, DG-PM, DG-PH) treated with phlorizin at 0.01%, 0.02%, and 0.04% (w/w) in diets were raised for 12 weeks. Supplementing with phlorizin reversed the loss of organ coefficient and body weight caused by D-galactose. The functional abilities of phlorizin on hippocampal-dependent spatial learning and memory, anti-oxidation, anti-inflammation were also observed. Meanwhile, phlorizin intervention upregulated the gene expression of Nrf2, GSH-PX, SOD1, decreased the gene expression of NF-κB, TLR-4, TNF-α, and IL-1β in the hippocampus, while enhanced the gene expression of JAM-A, Mucin2, Occludin in the caecum. Furthermore, a neurotransmitter of acetylcholine (ACh) was enhanced, while acetylcholinesterase (AChE) activity was inhibited by phlorizin administration. Moreover, phlorizin administration increased short-chain fatty acids (SCFAs) content, and reduced lipopolysaccharides (LPS) levels, which may relate to the rebuilding of gut microbiota homeostasis. Treatment with phlorizin may be an effective intervention for alleviating cognitive decline and gut microbiota dysbiosis.

Mucuna pruriens Seed Aqueous Extract Improved Neuroprotective and Acetylcholinesterase Inhibitory Effects Compared with Synthetic L-Dopa

L-dopa, a dopaminergic agonist, is the gold standard for the treatment of Parkinson’s disease. However, due to the long-term toxicity and adverse effects of using L-dopa as the first-line therapy for Parkinson’s disease, a search for alternative medications is an important current challenge. Traditional Ayurvedic medicine has suggested the use of Mucuna pruriens Linn. (Fabaceae) as an anti-Parkinson’s agent. The present study aimed to quantify the amount of L-dopa in M. pruriens seed extract by HPLC analysis. The cytotoxicity and neuroprotective properties of M. pruriens aqueous extract were investigated by two in vitro models including the serum deprivation method and co-administration of hydrogen peroxide assay. The results showed the significant neuroprotective activities of M. pruriens seed extracts at a concentration of 10 ng/mL. In addition, the effects of L-dopa and M. pruriens seed extract on in vitro acetylcholinesterase activities were studied. M. pruriens seed extract demonstrated acetylcholinesterase inhibitory activity, while synthetic L-dopa enhanced the activity of the enzyme. It can be concluded that the administration of M. pruriens seed might be effective in protecting the brain against neurodegenerative disorders such as Parkinson’s and Alzheimer’s diseases. M. prurience seed extract containing L-dopa has shown less acetylcholinesterase activity stimulation compared with L-dopa, suggesting that the extract might have a superior benefit for use in the treatment of Parkinson’s disease.

Isolation and acetylcholinesterase inhibitory activity of asterric acid derivatives produced by Talaromyces aurantiacus FL15, an endophytic fungus from Huperzia serrata

Alzheimer's disease (AD) is a neurodegenerative disease and the fourth leading cause of death after cardiovascular disease, tumors, and stroke. Acetylcholinesterase (AChE) inhibitors, which are based on cholinergic damage, remain the mainstream drugs to alleviate AD-related symptoms. This study aimed to explore novel AChE inhibitors produced by the endophytic fungus FL15 from Huperzia serrata. The fungus was identified as Talaromyces aurantiacus FL15 according to its morphological characteristics and ITS, 18S rDNA, and 28S rDNA sequence analysis. Subsequently, seven natural metabolites were isolated from strain FL15, and identified as asterric acid (1), methyl asterrate (2), ethyl asterrate (3), emodin (4), physcion (5), chrysophanol (6), and sulochrin (7). Compounds 1-3, which possess a diphenyl ether structure, exhibited highly selective and moderate AChE inhibitory activities with IC₅₀ values of 66.7, 23.3, and 20.1 μM, respectively. The molecular docking analysis showed that compounds 1-3 interacted with the active catalytic site and peripheral anionic site of AChE, and the esterification substitution groups at position 8 of asterric acid may contribute to its bioactivity. The asterric acid derivatives showed highly selective and moderate AChE inhibitory activities, probably via interaction with the peripheral anionic site and catalytic site of AChE. To the best of our knowledge, this study was the first report of the AChE inhibitory activity of asterric acid derivatives, which opens new perspectives for the design of more effective derivatives that could serve as a drug carrier for new chemotherapeutic agents to treat AD.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13205-022-03125-2.

Anti-diabetic effects of linarin from Chrysanthemi Indici Flos via AMPK activation

Objective

The purpose of this study is to investigate the anti-diabetic effects of linarin, a flavonoid extracted from Chrysanthemi Indici Flos (CIF), and its potential mechanisms.

Methods

The effects of linarin on cell viability and glucose consumption in HepG2 cells were measured. Meanwhile, monosodium glutamate (MSG) mouse model was constructed to monitor the changes of insulin tolerance, glucose tolerance, triglyceride and cholesterol. The protein expression levels of p-AMPK, p-ACC, PEPCK and p-GS were detected by Western blot.

Results

Linarin could increase the relative glucose consumption of HepG2 cells, improve insulin tolerance and glucose tolerance, and decrease the levels of triglyceride and cholesterol of MSG mice. Simultaneously, the expression levels of p-AMPK and p-ACC in HepG2 cells and the liver tissue of MSG mice were increased, while the expression levels of PEPCK and p-GS were decreased after treatment with linarin.

Conclusion

Insulin resistance could be ameliorated by linarin in type 2 diabetes, and its mechanism may be related to AMPK signaling pathway.

Plasmalogens improve swimming performance by modulating the expression of genes involved in amino acid and lipid metabolism, oxidative stress, and ferroptosis in an Alzheimer's disease zebrafish model

Plasmalogens (PLs) are critical to human health. Studies have reported a link between the downregulation of PLs levels and cognitive impairments in patients with Alzheimer's disease (AD). However, the underlying mechanisms remain to be clarified. In the present study, an AlCl₃-induced AD zebrafish model was established, and the model was used to elucidate the neuroprotective effects of PLs on AD by analysing the transcriptional profiles of zebrafish in the control, AD model, AD_PL, and PL groups. Chronic AlCl₃ exposure caused swimming performance impairments in the zebrafish, yet PLs supplementation could improve the dyskinesia recovery rate in the AD zebrafish model. Through transcriptional profiling, a total of 5413 statistically significant differentially expressed genes (DEGs) were identified among the groups. In addition to the DEGs involved in amino acid metabolism, we found that the genes related to iron homeostasis, lipid peroxidation, and oxidative stress, all of which contribute to ferroptosis, were dramatically altered among different groups. These results suggest that seafood-derived PLs, in addition to their role in eliminating oxidative stress, can improve the swimming performance in AlCl₃-exposed zebrafish partly by suppressing neuronal ferroptosis and accelerating synaptic transmission at the transcriptional level. This study provides evidence for PLs to be developed as a functional food supplement to relieve AD symptoms.

The cholinergic system, intelligence, and dental fluorosis in school-aged children with low-to-moderate fluoride exposure

Disruption of cholinergic neurotransmission can affect cognition, but little is known about whether low-to-moderate fluoride exposure affects cholinergic system and its effect on the prevalence of dental fluorosis (DF) and intelligence quotient (IQ). A cross-sectional study was conducted to explore the associations of moderate fluoride exposure and cholinergic system in relation to children's DF and IQ. We recruited 709 resident children in Tianjin, China. Ion selective electrode method was used to detect fluoride concentrations in water and urine. Cholinergic system was assessed by the detection of choline acetyltransferase (ChAT), acetylcholinesterase (AChE) and acetylcholine (ACh) levels in serum. Compared with children in the first quartile, those in fourth quartile the risk of either developing DF or IQ < 120 increased by 19% and 20% for water and urinary fluoride. The risk of having both increased by 58% and 62% in third and fourth quartile for water fluoride, 52% and 65% for urinary fluoride. Water fluoride concentrations were positively associated with AChE and negatively associated with ChAT and ACh, trends were same for urinary fluoride except for ACh. The risk of either developing DF or having non-high intelligence rose by 22% (95%CI: 1.07%, 1.38%) for the fourth quartile than those in the first quartile of AChE, for having the both, the risk was 1.27 (95%CI: 1.07, 1.50), 1.37 (95%CI: 1.17, 1.62) and 1.44 (95%CI: 1.23, 1.68) in second, third and fourth quartiles. The mediation proportion by AChE between water fluoride and either developing DF or IQ < 120 was 15.7%. For both to exist, the proportion was 6.7% and 7.2% for water and urinary fluoride. Our findings suggest low-to-moderate fluoride exposure was associated with dysfunction of cholinergic system for children. AChE may partly mediate the prevalence of DF and lower probability of having superior and above intelligence.

Linarin, a Glycosylated Flavonoid, with Potential Therapeutic Attributes: A Comprehensive Review

Many flavonoids, as eminent phenolic compounds, have been commercialized and consumed as dietary supplements due to their incredible human health benefits. In the present study, a bioactive flavone glycoside linarin (LN) was designated to comprehensively overview its phytochemical and biological properties. LN has been characterized abundantly in the Cirsium, Micromeria, and Buddleja species belonging to Asteraceae, Lamiaceae, and Scrophulariaceae families, respectively. Biological assessments exhibited promising activities of LN, particularly, the remedial effects on central nervous system (CNS) disorders, whereas the remarkable sleep enhancing and sedative effects as well as AChE (acetylcholinesterase) inhibitory activity were highlighted. Of note, LN has indicated promising anti osteoblast proliferation and differentiation, thus a bone formation effect. Further biological and pharmacological assessments of LN and its optimized semi-synthetic derivatives, specifically its therapeutic characteristics on osteoarthritis and osteoporosis, might lead to uncovering potential drug candidates.

Effects and mechanisms of natural products on Alzheimer's disease

Alzheimer's disease (AD) is the most common form of dementia in elderly people with a high incidence rate and complicated pathogenesis, and causes progressive cognitive deficit and memory impairment. Some natural products and bioactive compounds from natural sources show great potential in the prevention and treatment of AD, such as apple, blueberries, grapes, chili pepper, Monsonia angustifolia, cruciferous vegetables, Herba epimedii, Angelica tenuissima, Embelia ribes, sea cucumber, Cucumaria frondosa, green tea, Puer tea, Amanita caesarea and Inonotus obliquus, via reducing amyloid beta (Aβ) deposition, decreasing Tau hyperphosphorylation, regulating cholinergic system, reducing oxidative stress, inhibiting apoptosis and ameliorating inflammation. This review mainly summarizes the effects of some natural products and their bioactive compounds on AD with the potential molecular mechanisms.

Impact of Gut Microbiome Lactobacillus spp. in Brain Function and its Medicament towards Alzheimer’s Disease Pathogenesis

Alzheimer’s disease is neurodegenerative dementia which has significant health complications in the old age group. An imbalance in gut microbiota can influence to cause several diseases like chronic disorders, depression, type II diabetics, and neurological disorders like AD. Aging is one of the major causes of the development of neurodegenerative disease due to the decreasing levels of neurotransmitters, oxidative stress, chronic inflammation, and apoptosis. These harmful effects of aging can be prevented by probiotics usage. The gut-microbiota is capable to control the brain function through the gut-brain axis. Lactobacillus strains are considered as beneficial microorganism because of its importance of the maintenance in healthy intestinal microflora, immunomodulation, and intestinal pathogenic intervention. They have diverse applications in the medical field with properties like antioxidant, anticancer, anti-inflammatory, anti-proliferative, anti-obesity, and anti-diabetic activities. Probiotic supplementation with Lactobacillus strains shows an optimistic trend to use it as a significant therapy for cognitive symptoms. This review article put forwards the significance of the gut-brain axis and the contribution of Lactobacillus strains as a probiotic supplement and its therapeutic innovations for future aspects and the limitation to treat AD-related pathogenesis are briefly elucidated.

Advances of Zebrafish in Neurodegenerative Disease: From Models to Drug Discovery

Neurodegenerative disease (NDD), including Alzheimer’s disease, Parkinson’s disease, and amyotrophic lateral sclerosis, are characterized by the progressive loss of neurons which leads to the decline of motor and/or cognitive function. Currently, the prevalence of NDD is rapidly increasing in the aging population. However, valid drugs or treatment for NDD are still lacking. The clinical heterogeneity and complex pathogenesis of NDD pose a great challenge for the development of disease-modifying therapies. Numerous animal models have been generated to mimic the pathological conditions of these diseases for drug discovery. Among them, zebrafish (Danio rerio) models are progressively emerging and becoming a powerful tool for in vivo study of NDD. Extensive use of zebrafish in pharmacology research or drug screening is due to the high conserved evolution and 87% homology to humans. In this review, we summarize the zebrafish models used in NDD studies, and highlight the recent findings on pharmacological targets for NDD treatment. As high-throughput platforms in zebrafish research have rapidly developed in recent years, we also discuss the application prospects of these new technologies in future NDD research.

Studying CNS effects of Traditional Chinese Medicine using zebrafish models

ETHNOPHARMACOLOGICAL RELEVANCE

Although Traditional Chinese Medicine (TCM) has a millennia-long history of treating human brain disorders, its complex multi-target mechanisms of action remain poorly understood. Animal models are currently widely used to probe the effects of various TCMs on brain and behavior. The zebrafish (Danio rerio) has recently emerged as a novel vertebrate model organism for neuroscience research, and is increasingly applied for CNS drug screening and development.

AIM OF THE STUDY

As zebrafish models are only beginning to be applied to studying TCM, we aim to provide a comprehensive review of the TCM effects on brain and behavior in this fish model species.

MATERIALS AND METHODS

A comprehensive search of published literature was conducted using biomedical databases (Web of Science, Pubmed, Sciencedirect, Google Scholar and China National Knowledge Internet, CNKI), with key search words zebrafish, brain, Traditional Chinese Medicine, herbs, CNS, behavior.

RESULTS

We recognize the developing utility of zebrafish for studying TCM, as well as outline the existing model limitations, problems and challenges, as well as future directions of research in this field.

CONCLUSIONS

We demonstrate the growing value of zebrafish models for studying TCM, aiming to improve our understanding of TCM' therapeutic mechanisms and potential in treating brain disorders.

In silico and in vitro anti-AChE activity investigations of constituents from Mytragyna speciosa for Alzheimer's disease treatment

Acetylcholinesterase (AChE), one of the major therapeutic strategies for the treatment of Alzheimer's disease (AD) is to increase the acetylcholine (ACh) level in the brain by inhibiting the biological activity of AChE. In this present work, a set of alkaloids and flavonoids against AChE enzyme were screened by computational chemistry techniques. The docking results showed that among alkaloid compounds the oxindole alkaloid namely mitragynine oxidole B (MITOB) and the indole alkaloids namely mitragynine (MIT) exhibited a good binding affinity towards AChE. These two compounds were then studied by molecular dynamics (MD) simulations. The binding free energy calculation and ligand-protein binding pattern suggested that both alkaloids could interact with AChE very well. Since MIT is the main alkaloid constituent of Mytragyna speciose leaves, this compound was isolated from M. speciose leaves and tested for anti-AChE activity. As a result, the isolated MIT had an inhibitory activity with pIC₅₀ value of 3.57. This finding provided that the mitragynine compound has the potential to be as a therapeutic agent for further anti-AChE drug development in treatment of Alzheimer's disease.

Linarin Protects the Kidney against Ischemia/Reperfusion Injury via the Inhibition of Bioactive ETS2/IL-12

Ischemia/reperfusion injury (IRI), a participant in acute kidney injury (AKI), can occur as a series of pathological processes such as inflammation. Linarin (LIN) has been widely used for different diseases. To confirm the anti-inflammatory value and relevant mechanism of LIN during IRI, in vivo and vitro models were established. LIN or dissolvent was given, and histologic analysis, quantitative (q)RT-PCR, serum creatinine and blood urea nitrogen testing were used to evaluate kidney injury. Microarray analysis, protein-protein interaction (PPI) analysis and molecular docking were used to identify the target protein of LIN, and small interfering RNA (siRNA) transfection was applied to explore the crucial role of identified protein. First, we found that LIN inhibited kidney injury in an in vivo IRI model and decreased the expression of interleukin-12 (IL-12) p40 in vivo and in vitro IRI models. To explore the mechanism of LIN, we collected raw data from a public microarray database and identified E26 oncogene homolog 2 (ETS2) as a crucial protein of LIN according to microarray analysis and PPI. Meanwhile, qRT-PCR indicated that IL-12 p40 showed no significant difference between ETS2 knock down group and LIN treated ETS2 knock down group after hypoxia reoxygenation treatment. In addition, according to molecular docking the contact area is highly conserved and located on a PPI domain of ETS2 which indicates that LIN may alter the interaction with synergistic proteins in the regulation of IL-12 p40 expression. Our study demonstrated the anti-inflammatory effect of LIN during IRI-AKI, broadening the medicinal value of LIN and the therapeutic options for IRI-AKI.

Investigation of Experimental and In Silico Physicochemical Properties of Thiazole-Pyridinium Anti-Acetylcholinesterase Derivatives with Potential Anti-Alzheimer’s Activity

Background: Physicochemical properties play important role in fundamental issues like absorption and distribution of pharmaceuticals to the target tissue. This is particularly importantfor drugs acting in central nervous system (CNS). In this study, physicochemical properties of previously synthesized thiazole-pyridinium derivatives with anti-acetylcholinesterase activity and possible anti-Alzheimer effect were studied. Methods: Partition coefficient (n-octanol/water) and chromatographic Rf values for the studied compounds were determined using shake flask and high performance thin layer chromatography(HPTLC) methods, respectively. Different druglikeness properties of the compounds were also calculated using available software and web-servers. Results: The experimentally determined logarithm of partition coefficients (log P) for the studied compounds were in the range of -1.00 to -0.38. The Rf values for the studied compounds under the applied chromatographic condition ranged between 0.38 to 0.58. Moreover, calculated physicochemical properties, and druglikeness scores of the studied thiazole-pyridiniumderivatives and matching piperidine analogues were predicted. Furthermore, some ADMETfeatures of studied compounds like toxicity and metabolism by CYP450 (2C9, 2D6, 3A4, 1A2and 2C19) enzymes were predicted. Conclusion: The ranges of experimental and calculated LogP values for the studied thiazolepyridinumswere close. However, the determined Rf values showed relatively better correlation to the predicted LogP values indicating the suitability of used chromatographic method for comparing the lipophilicity of the positively charged pyridinium derivatives. The studied compounds were predicted to pass GI membrane and reach the CNS where they can exert their effects. In silico studies indicate that the piperidine counterparts of the studied thiazolepyridiniumsmay represent anti-Alzheimer agents with improved druglikeness properties.

Integrated network pharmacology and zebrafish model to investigate dual-effects components of Cistanche tubulosa for treating both Osteoporosis and Alzheimer's Disease

ETHNOPHARMACOLOGICAL RELEVANCE

Osteoporosis (OP) and Alzheimer's disease (AD) are common geriatric concurrent diseases, and many studies indicate the connection of their pathogenesis. Cistanche tubulosa (Schenk) Wight (CT) is a widely used traditional Chinese medicine and has been extensively applied to treat OP and AD, respectively. However, the active ingredients for both concurrent diseases simultaneously and underlying mechanisms are limited.

AIM OF STUDY

This work aimed at establishing an effective and reliable network screening method to find dual-effects compounds in CT that can protect AD and OP concurrently. And it will provide new perspectives of the link between OP and AD on molecular mechanisms.

MATERIAL AND METHODS

The dual-effects of CT were systematically analyzed with integrating multiple databases and extensive analysis at a network pharmacology level. Classified drug-target interaction network was constructed to reveal differences in effects between different types of compounds. To prove the effectiveness of this network, some compounds were selected to verify in Pre-induced OP model and AlCl₃-induced AD model of zebrafish according to the topological parameters.

RESULTS

22 dual-effects active ingredients in CT were initially screened out via network pharmacology with a closely connection with 81 OP and AD-related targets. Classified network analysis found the better bioactivities of phenylethanoid glycosides and flavonoids. The dual-effects of four selected compounds demonstrated that the network is reasonable and effective, suggesting the dual-effects of the remaining 18 compounds. Moreover, we identified 9 putative targets and two pathways that were significantly related to OP and AD.

CONCLUSIONS

We successfully identified 22 dual-effects active components in CT. This systematic screening strategy provided a new protocol to objectively discover multi-effects compounds of traditional Chinese medicine, and even a macroscopic perspective that will improve our understanding of the link between OP and AD on molecular mechanisms.

Clofibrate, a PPAR-α agonist, abrogates sodium fluoride-induced neuroinflammation, oxidative stress, and motor incoordination via modulation of GFAP/Iba-1/anti-calbindin signaling pathways

Fluoride is an environmental contaminant that is ubiquitously present in air, water, and soil. It is commonly added in minute quantity to drinking water, toothpaste, and mouth rinses to prevent tooth decay. Epidemiological findings have demonstrated that exposure to fluoride induced neurodevelopmental toxicity, developmental neurotoxicity, and motor disorders. The neuroprotective effect of clofibrate, a peroxisome proliferator-activated receptor alpha agonist, was investigated in the present study. Forty male Wistar rats were used for this study and randomly grouped into 10 rats per group as control, sodium fluoride (NaF) alone (300 ppm), NaF plus clofibrate (250 mg/kg), and NaF plus lisinopril (10 mg/kg), respectively, for 7 days. NaF was administered in drinking water while clofibrate and lisinopril were administered by oral gavage. Markers of neuronal inflammation and oxidative stress, acetylcholinesterase activity, and neurobehavioral (hanging wire and open field) tests were performed. Immunohistochemistry was performed on brain tissues, and they were probed with glial fibrillary acidic protein, ionized calcium-binding adaptor molecule 1, and cerebellar Ca²⁺ -binding protein calbindin-D28k. The results showed that NaF significantly increased of oxidative stress and neuroinflammation and inhibited AChE activity. Immunostaining showed reactive astrocytes, microgliosis, loss of dendritic spines, and arborization in Purkinje cells in rats administered only NaF. Neurobehavioral results showed that cotreatment of NaF with clofibrate improved muscular strength and locomotion, reduced anxiety, and significantly reduced astrocytic count. Overall, cotreatment of NaF with either clofibrate or lisinopril showed neuroprotective effects by mitigating neuronal inflammation and oxidative and motor incoordination. Hence, clofibrate could be seen as a novel drug candidate against neurodegeneration and motor disorders.