Amelioration of cognitive deficit in zebrafish by an undescribed anthraquinone from Juglans regia L.: An in-silico, in-vitro and in-vivo approach

Utilizing alternative in vivo animal models for food safety and toxicity: A focus on thermal process contaminant acrylamide

Rodent models have traditionally been used to assess the toxicity of food chemicals, but this approach is costly, time-consuming, and raises ethical concerns. Alternatively, non-mammalian models such as Drosophila melanogaster, Danio rerio, and Caenorhabditis elegans have been shown to be suitable for studying the toxicity of food hazards. Their advantages include low cost, short life cycles, adaptability to high-throughput screening, and adherence to the 3R principles of replacement, reduction, and refinement. These models have been extensively studied in the context of acrylamide toxicity, a common food contaminant. This article comprehensively reviews the biological characteristics of non-mammalian models, recent advances and challenges in acrylamide toxicity research using these models, and explores the potential of natural plant compounds in ameliorating acrylamide toxicity. The review aims to guide research using non-mammalian models for food safety assessment.

An Overview of the Natural Neuroprotective Agents for the Management of Cognitive Impairment Induced by Scopolamine in Zebrafish (Danio rerio)

Alzheimer's Disease (AD) is a neurodegenerative disorder mainly characterized by dementia and cognitive decline. AD is essentially associated with the presence of aggregates of the amyloid-β peptide and the hyperphosphorylated microtubule-associated protein tau. The available AD therapies can only alleviate the symptoms; therefore, the development of natural treatments that exhibit neuroprotective effects and correct the behavioral impairment is a critical requirement. The present review aims to collect the natural substances that have been evaluated for their neuroprotective profile against AD-like behaviors induced in zebrafish (Danio rerio) by scopolamine. We focused on articles retrieved from the PubMed database via preset searching strings from 2010 to 2023. Our review assembled 21 studies that elucidated the activities of 28 various natural substances, including bioactive compounds, extracts, fractions, commercial compounds, and essential oils. The listed compounds enhanced cognition and showed several mechanisms of action, namely antioxidant potential, acetylcholinesterase's inhibition, and reduction of lipid peroxidation. Additional studies should be achieved to demonstrate their preventive and therapeutic activities in cellular and rodent models. Further clinical trials would be extremely solicited to support more insight into the neuroprotective effects of the most promising drugs in an AD context.

The influence of sex and age differences in an adult zebrafish (Danio rerio) T-maze model of cognition

The zebrafish (Danio rerio) model is increasingly popular in neurobehavioral research, and behavioral outcomes are commonly evaluated in studies on neurodegeneration and neurotoxicity. Sex and age have been identified as important variables in cognition studies; however, these factors are often underreported in published studies that use the zebrafish model, leading to uncertainty about their impact in zebrafish T-maze experiments. In this study, we evaluated the role of sex and age in zebrafish cognitive function using a 5-day T-maze task. Our results demonstrated that female and younger zebrafish had increased learning and memory capacity. These findings highlighted the importance of considering and reporting sex and age in experimental design in zebrafish cognitive neurobehavioral studies.

Zebrafish models for studying cognitive enhancers

Cognitive decline is commonly seen both in normal aging and in neurodegenerative and neuropsychiatric diseases. Various experimental animal models represent a valuable tool to study brain cognitive processes and their deficits. Equally important is the search for novel drugs to treat cognitive deficits and improve cognitions. Complementing rodent and clinical findings, studies utilizing zebrafish (Danio rerio) are rapidly gaining popularity in translational cognitive research and neuroactive drug screening. Here, we discuss the value of zebrafish models and assays for screening nootropic (cognitive enhancer) drugs and the discovery of novel nootropics. We also discuss the existing challenges, and outline future directions of research in this field.

In Vitro and In Vivo Investigations of Chromone Derivatives as Potential Multitarget-Directed Ligands: Cognitive Amelioration Utilizing a Scopolamine-Induced Zebrafish Model

Alzheimer's disease is a complex neurological disorder linked with multiple pathological hallmarks. The interrelation of therapeutic targets assists in the enhancement of cognitive decline through interference with overall neuronal transmission. We have synthesized and screened various chromone derivatives as potential multitarget-directed ligands for the effective treatment of Alzheimer's disease. The synthesized compounds exhibited multipotent activity against AChE, BuChE, MAO-B, and amyloid β aggregation. Three potent compounds, i.e., VN-3, VN-14, and VN-19 were identified that displayed remarkable activities against different targets. These compounds displayed IC50 values of 80 nM, 2.52 μM, and 140 nM against the AChE enzyme, respectively, and IC50 values of 2.07 μM, 70 nM, and 450 nM against the MAO-B isoform, respectively. VN-3 displayed potent activity against self-induced Aβ1-42 aggregation with inhibition of 58.3%. In the ROS inhibition studies, the most potent compounds reduced the intracellular ROS levels up to 80% in SH-SY5Y cells at 25 μM concentration. The compounds were found to be neuroprotective and noncytotoxic even at a concentration of 25 μM against SH-SY5Y cells. In silico studies showed that the compounds were nicely accommodated in the active sites of the receptors along with thermodynamically stable orientations. Compound VN-19 exhibited a balanced multitargeting profile against AChE, BuChE, MAO-B, and Aβ1-42 enzymes and was further evaluated for in vivo activities on the scopolamine-induced zebrafish model. VN-19 was found to ameliorate the cognitive decline in zebrafish brains by protecting them against scopolamine-induced neurodegeneration. Thus, VN-3, VN-14, and VN-19 were identified as potent multitarget-directed ligands with a balanced activity profile against different targets and can be developed as therapeutics for AD.

Discovery of Enzyme Inhibitors from Mangrove Sediment Derived Fungus Trichoderma harzianum SCSIO 41051

One new fatty acid derivative, (2E,4E)-6,7-dihydroxy-2-methylocta-2,4-dienoic acid (1), and 16 known compounds (2-17) were isolated from the mangrove sediment derived fungus Trichoderma harzianum SCSIO 41051. Their structures were established by spectroscopic methods, computational ECD, and Mo2(OAc)4-induced ECD experiment. All the compounds were evaluated for their acetylcholinesterase (AChE) and pancreatic lipase (PL) inhibition. Compounds 9 and 14 exhibited moderate AChE inhibitory activities with IC50 values of 2.49 and 2.92 μM, respectively, which compounds 8 and 9 displayed moderate inhibition on PL with IC50 value of 2.30 and 2.34 μM, respectively.

Fagopyrum tataricum (L.) Gaertn interacts with Gsk-3β/Nrf-2 signalling to protect neurotoxicity in a zebrafish model

ETHNOPHARMACOLOGICAL RELEVANCE

Fagopyrum tataricum (L.) Gaertn is used as a folk medicine in many Asian countries due to its anti-inflammatory, antioxidant, and several other health-promoting properties. It is also prescribed to improve neurocognitive functions and alleviate inflammatory conditions.

AIM OF THE STUDY

Oxidative stress and neuroinflammation plays a crucial role in neurodegenerative conditions. Hence, based on the ethnomedical claims and available literature, the present study investigated neuroprotective efficacy of a seed extract (ft-ext) of Fagopyrum tataricum against acrylamide (ACR)-induced neurotoxicity.

MATERIALS AND METHODS

The phytochemical characterization of ft-ext was performed by a high-performance liquid chromatography method. Molecular interactions of the identified compounds of ft-ext were studied using an in-silico docking tool. An in-vitro protein denaturation assay was done to check anti-inflammatory activity. The 5 days' post-fertilized zebrafish larvae were exposed to 1 mM and 2.5 mM ACR with or without ft-ext for 72 h to study its neuroprotective efficacy. Real-time polymerase chain reaction and western blotting studies were performed to analyse the oxidative stress-related gene and protein expressions respectively.

RESULTS

The extract showed the presence of chlorogenic acid, rutin, caffeic acid, vitexin, syringic acid, quercetin, p-coumaric acid, kaempferol, and ferulic acid. In-vitro protein denaturation assay of ft-ext showed a potent anti-inflammatory effect. The ft-ext improved ACR-mediated locomotor deficit and reduced overall mortality in the larvae. The brain lipid peroxidation and protein carbonylation results revealed an elevated level of oxidative stress in the ACR-treated group, which was reduced in ft-ext-treated larvae. The extract treatment increased the expression of nrf2, gpx, and hmox1a, while simultaneously downregulated trxr2 levels in the brain of larvae exposed to ACR. The treatment also showed inactivation of Gsk-3β, thus maintaining a normal pool of Nrf2 and β-catenin. Molecular docking of identified compounds of ft-ext showed possible hydrogen and hydrophobic interactions with Gsk-3β.

CONCLUSION

The ft-ext prevents ACR-mediated neurotoxicity by suppressing Gsk-3β mediated oxidative stress.

Naturally Occurring Cholinesterase Inhibitors from Plants, Fungi, Algae, and Animals: A Review of the Most Effective Inhibitors Reported in 2012-2022

Since the development of the "cholinergic hypothesis" as an important therapeutic approach in the treatment of Alzheimer's disease (AD), the scientific community has made a remarkable effort to discover new and effective molecules with the ability to inhibit the enzyme acetylcholinesterase (AChE). The natural function of this enzyme is to catalyze the hydrolysis of the neurotransmitter acetylcholine in the brain. Thus, its inhibition increases the levels of this neurochemical and improves the cholinergic functions in patients with AD alleviating the symptoms of this neurological disorder. In recent years, attention has also been focused on the role of another enzyme, butyrylcholinesterase (BChE), mainly in the advanced stages of AD, transforming this enzyme into another target of interest in the search for new anticholinesterase agents. Over the past decades, Nature has proven to be a rich source of bioactive compounds relevant to the discovery of new molecules with potential applications in AD therapy. Bioprospecting of new cholinesterase inhibitors among natural products has led to the discovery of an important number of new AChE and BChE inhibitors that became potential lead compounds for the development of anti-AD drugs. This review summarizes a total of 260 active compounds from 142 studies which correspond to the most relevant (IC50 ≤ 15 μM) research work published during 2012-2022 on plant-derived anticholinesterase compounds, as well as several potent inhibitors obtained from other sources like fungi, algae, and animals.

Neurobehavioral impairments from chromium exposure: Insights from a zebrafish model and drug validation

We have developed a zebrafish model to explore the alterations in neurobehaviors resulting from both acute and chronic exposure to chromium (Cr). Zebrafish exposed to half (HC group: 19.7 mg/L) and a quarter (LC group: 9.85 mg/L) of the LD50 concentration of Cr for a span of 2 weeks exhibited aberrant locomotion, heightened anxiety, cognitive impairment, and reduced aggression - hallmark traits reminiscent of an Alzheimer's Disease (AD)-like syndrome. Furthermore, zebrafish exposed to an environmentally relevant concentration of Cr (EC group: 100 μg/L) for an extended period of 9 weeks exhibited behaviors comparable to those observed in the HC group. Moreover, the study investigated the neuroprotective effects of donepezil (Don), galantamine (Gal) and resveratrol (Res) drugs in response to neurobehavioral impairments induced by Cr (VI) exposure in zebrafish. Don and Res effectively protect the zebrafish from Cr (VI)-induced anxiety, and memory impairment. Furthermore, Cr (VI) exposure induced heightened oxidative stress while simultaneously diminishing antioxidant enzyme levels. Remarkably, these effects were counteracted in the drug-treated groups. Likewise, exposure to Cr (VI) led to an increase in the expression of genes linked to AD and neuroinflammation. Nevertheless, drug treatment reversed this effect in Cr (VI)-exposed fish. The results of our study highlight the potentials of zebrafish model in demonstrating neurobehavioral impairments induced by Cr (VI), thereby paving the way for its utilization in vivo neurobehaviors investigations and pharmaceutical screening.

Chemo-kindling in adult zebrafish alters spatial cognition but not social novelty recognition

In the past decades, zebrafish have gathered immense attention and importance in the field of neurological sciences. In the case of epilepsy, zebrafish have appeared as a promising acute animal model for the screening and identification of potential antiepileptic molecules. However, the necessity for establishing competent chronic models of epilepsy in zebrafish is apparent. In this regard, recently we developed a chemo-kindling zebrafish model with a better clinical resemblance. In the present study, an attempt to examine the effect of pentylenetetrazole (PTZ)-induced kindling on the cognitive functions of zebrafish was made. In brief, adult zebrafish were repetitively given a sub-effective concentration of PTZ, till the onset of clonic-tonic seizures, entitled as kindled. Thereafter, T-maze test and social recognition memory test were conducted to evaluate spatial memory and social novelty recognition memory of the fish. At the end, both the groups were sacrificed and the brains were isolated to estimate neurotransmitter and gene expression levels. It was observed that PTZ kindling induced spatial cognition deficits and lower social exploration in zebrafish. However, it didn't change the novelty recognition memory of kindled zebrafish. The results of genes and neurotransmitters estimations in the brain also supported the behavioural findings. The results concluded that PTZ kindling alters spatial cognitive functions in adult zebrafish without affecting the social novelty recognition memory.

Natural Inhibitors of Cholinesterases: Chemistry, Structure-Activity and Methods of Their Analysis

This article aims to provide an updated description and comparison of the data currently available in the literature (from the last 15 years) on the studied natural inhibitors of cholinesterases (IChEs), namely, acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). These data also apply to the likely impact of the structures of the compounds on the therapeutic effects of available and potential cholinesterase inhibitors. IChEs are hitherto known compounds with various structures, activities and origins. Additionally, multiple different methods of analysis are used to determine the cholinesterase inhibitor potency. This summary indicates that natural sources are still suitable for the discovery of new compounds with prominent pharmacological activity. It also emphasizes that further studies are needed regarding the mechanisms of action or the structure-activity correlation to discuss the issue of cholinesterase inhibitors and their medical application.

Zebrafish: A Pharmacological Model for Learning and Memory Research

Learning and memory are essential to organism survival and are conserved across various species, especially vertebrates. Cognitive studies involving learning and memory require using appropriate model organisms to translate relevant findings to humans. Zebrafish are becoming increasingly popular as one of the animal models for neurodegenerative diseases due to their low maintenance cost, prolific nature and amenability to genetic manipulation. More importantly, zebrafish exhibit a repertoire of neurobehaviors comparable to humans. In this review, we discuss the forms of learning and memory abilities in zebrafish and the tests used to evaluate the neurobehaviors in this species. In addition, the pharmacological studies that used zebrafish as models to screen for the effects of neuroprotective and neurotoxic compounds on cognitive performance will be summarized here. Lastly, we discuss the challenges and perspectives in establishing zebrafish as a robust model for cognitive research involving learning and memory. Zebrafish are becoming an indispensable model in learning and memory research for screening neuroprotective agents against cognitive impairment.

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.

A network pharmacology analysis on drug-like compounds from Ganoderma lucidum for alleviation of atherosclerosis

Ganoderma lucidum (GL) is known as a potent alleviator against chronic inflammatory disease like atherosclerosis (AS), but its mechanisms against AS have not been unveiled. This research aimed to identify the key compounds(s) and mechanism(s) of GL against AS through network pharmacology. The compounds from GL were identified by gas chromatography-mass spectrum (GC-MS), and SwissADME screened their physicochemical properties. Then, the target(s) associated with the screened compound(s) or AS related targets were identified by public databases, and we selected the overlapping targets using a Venn diagram. The networks between overlapping targets and compounds were visualized, constructed, and analyzed by RStudio. Finally, we performed a molecular docking test (MDT) to explore key target(s), compound(s), on AutoDockVina. A total of 35 compounds in GL were detected via GC-MS, and 34 compounds (accepted by Lipinski's rule) were selected as drug-like compounds (DLCs). A total of 34 compounds were connected to the number of 785 targets, and DisGeNET and Online Mendelian Inheritance in Man (OMIM) identified 2,606 AS-related targets. The final 98 overlapping targets were extracted between the compounds-targets and AS-related targets. On Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment, the number of 27 signaling pathways were sorted out, and a hub signaling pathway (MAPK signaling pathway), a core gene (PRKCA), and a key compound (Benzamide, 4-acetyl-N-[2,6-dimethylphenyl]) were selected among the 27 signaling pathways via MDT. Overall, we found that the identified 3 DLCs from GL have potent anti-inflammatory efficacy, improving AS by inactivating the MAPK signaling pathway. PRACTICAL APPLICATIONS: Ganoderma lucidum (GL) has been used as a medicinal or edible mushroom for chronic inflammatory patients: diabetes mellitus and dyslipidemia, especially atherosclerosis (AS). Until now, the majority of mushroom research has been implemented regarding β-glucan derivatives with very hydrophilic physicochemical properties. It implies that β-glucan or its derivatives have poor bioavailability. Hence, we have involved GC-MS in identifying lipophilic compounds from GL, which filtered them in silico to sort drug-like compounds (DLCs). Then, we retrieved targets associated with the DLCs, and identified a key signaling pathway, key targets, and key compounds against AS. In this paper, we utilized bioinformatics and network pharmacology theory to understand the uncovered pharmacological mechanism of GL on AS. To sum things up, our analysis elucidates the relationships between signaling pathways, targets, and compounds in GL. Ultimately, this work provides biochemical evidence to identify the therapeutic effect of GL on AS, and a scientific basis for deciphering the key mechanism on DLCs of GL against AS.