Tanshinone IIA exhibits anticonvulsant activity in zebrafish and mouse seizure models

Investigation of the mechanism of tanshinone IIA to improve cognitive function via synaptic plasticity in epileptic rats

CONTEXT

Tanshinone IIA is an extract of Salvia miltiorrhiza Bunge (Labiatae) used to treat cardiovascular disorders. It shows potential anticonvulsant and cognition-protective properties.

OBJECTIVE

We investigated the mechanism of tanshinone IIA on antiepileptic and cognition-protective effects in the model of epileptic rats.

MATERIALS AND METHODS

Lithium chloride (LiCl)-pilocarpine-induced epileptic Wistar rats were randomly assigned to the following groups (n = 12): control (blank), model, sodium valproate (VPA, 189 mg/kg/d, positive control), tanshinone IIA low dose (TS IIA-L, 10 mg/kg/d), medium dose (TS IIA-M, 20 mg/kg/d) and high dose (TS IIA-H, 30 mg/kg/d). Then, epileptic behavioural observations, Morris water maze test, Timm staining, transmission electron microscopy, immunofluorescence staining, western blotting and RT-qPCR were measured.

RESULTS

Compared with the model group, tanshinone IIA reduced the frequency and severity of seizures, improved cognitive impairment, and inhibited hippocampal mossy fibre sprouting score (TS IIA-M 1.50 ± 0.22, TS IIA-H 1.17 ± 0.31 vs. model 2.83 ± 0.31), as well as improved the ultrastructural disorder. Tanshinone IIA increased levels of synapse-associated proteins synaptophysin (SYN) and postsynaptic dense substance 95 (PSD-95) (SYN: TS IIA 28.82 ± 2.51, 33.18 ± 2.89, 37.29 ± 1.69 vs. model 20.23 ± 3.96; PSD-95: TS IIA 23.10 ± 0.91, 26.82 ± 1.41, 27.00 ± 0.80 vs. model 18.28 ± 1.01).

DISCUSSION AND CONCLUSIONS

Tanshinone IIA shows antiepileptic and cognitive function-improving effects, primarily via regulating synaptic plasticity. This research generates a theoretical foundation for future research on potential clinical applications for tanshinone IIA.

Chemically-induced epileptic seizures in zebrafish: A systematic review

The use of zebrafish as a model organism is gaining evidence in the field of epilepsy as it may help to understand the mechanisms underlying epileptic seizures. As zebrafish assays became popular, the heterogeneity between protocols increased, making it hard to choose a standard protocol to conduct research while also impairing the comparison of results between studies. We conducted a systematic review to comprehensively profile the chemically-induced seizure models in zebrafish. Literature searches were performed in PubMed, Scopus, and Web of Science, followed by a two-step screening process based on inclusion/exclusion criteria. Qualitative data were extracted, and a sample of 100 studies was randomly selected for risk of bias assessment. Out of the 1058 studies identified after removing duplicates, 201 met the inclusion criteria. We found that the most common chemoconvulsants used in the reviewed studies were pentylenetetrazole (n = 180), kainic acid (n = 11), and pilocarpine (n = 10), which increase seizure severity in a dose-dependent manner. The main outcomes assessed were seizure scores and locomotion. Significant variability between the protocols was observed for administration route, duration of exposure, and dose/concentration. Of the studies subjected to risk of bias assessment, most were rated as low risk of bias for selective reporting (94%), baseline characteristics of the animals (67%), and blinded outcome assessment (54%). Randomization procedures and incomplete data were rated unclear in 81% and 68% of the studies, respectively. None of the studies reported the sample size calculation. Overall, these findings underscore the need for improved methodological and reporting practices to enhance the reproducibility and reliability of zebrafish models for studying epilepsy. Our study offers a comprehensive overview of the current state of chemically-induced seizure models in zebrafish, highlighting the common chemoconvulsants used and the variability in protocol parameters. This may be particularly valuable to researchers interested in understanding the underlying mechanisms of epileptic seizures and screening potential drug candidates in zebrafish models.

Tanshinone IIA attenuates valvular interstitial cells' calcification induced by oxidized low density lipoprotein via reducing endoplasmic reticulum stress

Recent studies revealed that endoplasmic reticulum (ER) stress played an emerging role of in valve calcification. Tanshinone IIA (TanIIA) has been a research hotspot in cardiovascular diseases. Previously we found that sodium TanIIA dampened the pathological phenotype transition of valvular interstitial cells (VICs) by affecting ER stress published in Chinese Journal. Here, we test the hypothesis that TanIIA attenuates the pro-osteogenic effects of oxidized low-density lipoprotein (oxLDL) in VICs by reducing induction of ER stress. Patients' aortic valve (AV) was collected, and porcine VICs were cultured for in vitro model. ER stress markers were tested in human leaflets by immunostaining. Immunoblotting were used to test the osteoblastic factors such as Runx2, osteocalcin, and ER stress markers GRP78, CHOP, XBP1, etc. Alkakine phosphate (ALP) activity assay were used to test the activity of ALP kinase. Pro-inflammatory gene expression was detected by polymerase chain reaction. As a result, ER stress markers were elevated in patients' calcified AVs. OxLDL induced osteogenesis and inflammation via promoting ER stress. TanIIA attenuated oxLDL induced ER stress. TanIIA also inhibited theosteoblastic factors and inflammatory cytokine expressions in VICs. In conclusion, our data provide evidence that TanIIA exerts anti-inflammation and anti-osteogenic effects in VICs by attenuating ER stress, and ER stress acts as an important regulator in oxLDL induced VICs' phenotype transition.

Therapeutic prospects of naturally occurring p38 MAPK inhibitors tanshinone IIA and pinocembrin for the treatment of SARS-CoV-2-induced CNS complications

P38 mitogen-activated protein kinase (p38 MAPK) signaling pathway is closely related to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) replication and hyperinflammatory responses in coronavirus disease 2019 (COVID-19). Therefore, blood-brain barrier-penetrating p38 MAPK inhibitors have good potential for the treatment of central nervous system (CNS) complications of COVID-19. The aim of the present study is the characterization of the therapeutic potential of tanshinone IIA and pinocembrin for the treatment of CNS complications of COVID-19. Studies published in high-quality journals indexed in databases Scopus, Web of Science, PubMed, and so forth were used to review the therapeutic capabilities of selected compounds. In continuation of our previous efforts to identify agents with favorable activity/toxicity profiles for the treatment of COVID-19, tanshinone IIA and pinocembrin were identified with a high ability to penetrate the CNS. Considering the nature of the study, no specific time frame was determined for the selection of studies, but the focus was strongly on studies published after the emergence of COVID-19. By describing the association of COVID-19-induced CNS disorders with p38 MAPK pathway disruption, this study concludes that tanshinone IIA and pinocembrin have great potential for better treatment of these complications. The inclusion of these compounds in the drug regimen of COVID-19 patients requires confirmation of their effectiveness through the conduction of high-quality clinical trials.

Zebrafish as a robust preclinical platform for screening plant-derived drugs with anticonvulsant properties-a review

Traditionally, selected plant sources have been explored for medicines to treat convulsions. This continues today, especially in countries with low-income rates and poor medical systems. However, in the low-income countries, plant extracts and isolated drugs are in high demand due to their good safety profiles. Preclinical studies on animal models of seizures/epilepsy have revealed the anticonvulsant and/or antiepileptogenic properties of, at least some, herb preparations or plant metabolites. Still, there is a significant number of plants known in traditional medicine that exert anticonvulsant activity but have not been evaluated on animal models. Zebrafish is recognized as a suitable in vivo model of epilepsy research and is increasingly used as a screening platform. In this review, the results of selected preclinical studies are summarized to provide credible information for the future development of effective screening methods for plant-derived antiseizure/antiepileptic therapeutics using zebrafish models. We compared zebrafish vs. rodent data to show the translational value of the former in epilepsy research. We also surveyed caveats in methodology. Finally, we proposed a pipeline for screening new anticonvulsant plant-derived drugs in zebrafish ("from tank to bedside and back again").

Tanshinone-IIA mediated neuroprotection by modulating neuronal pathways

The progression of neurological diseases is mainly attributed to oxidative stress, apoptosis, inflammation, and trauma, making them a primary public concern. Since no drugs can stop these neurological disorders from happening, active phytochemical intervention has been suggested as a possible treatment. Among the several phytochemicals being studied for their potential health advantages, tanshinone-IIA (Tan-IIA ) stands out due to its wide range of therapeutic effects. Tan-IIA, derived from the Salvia miltiorrhiza plant, is a phenanthrenequinone. The pharmacological characteristics of Tan-IIAagainst various neurodegenerative and neuropsychiatric illnesses have led researchers to believe that the compound possesses neuroprotective potential. Tan-IIA has therapeutic potential in treating neurological diseases due to its capacity to cross the blood-brain barrier and its broad range of activities. In treating neurological disorders, Tan-IIA has been shown to have neuroprotective effects such as anti-apoptotic, anti-inflammatory, BBB protectant, and antioxidant properties. This article concisely summarises the latest scientific findings about the cellular and molecular aspects of Tan-IIA neuroprotection in relation to various neurological diseases. The results of preclinical studies on Tan-IIA provide insight into its potential application in future therapeutic development. This molecule rapidly establishes as a prominent bioactive compound for clinical research.

Treating Epilepsy with Natural Products: Nonsense or Possibility?

Epilepsy is a neurological disease characterized by recurrent seizures that can lead to uncontrollable muscle twitching, changes in sensitivity to sensory perceptions, and disorders of consciousness. Although modern medicine has effective antiepileptic drugs, the need for accessible and cost-effective medication is urgent, and products derived from plants could offer a solution. For this review, we have focused on natural compounds that have shown anticonvulsant activity in in vivo models of epilepsy at relevant doses. In some cases, the effects have been confirmed by clinical data. The results of our search are summarized in tables according to their molecular targets. We have critically evaluated the data we present, identified the most promising therapeutic candidates, and discussed these in the text. Their perspectives are supported by both pharmacokinetic properties and potential interactions. This review is intended to serve as a basis for future research into epilepsy and related disorders.

Designing the 5HT2BR structure and its modulation as a therapeutic target for repurposing approach in drug-resistant epilepsy

The study intends to repurpose FDA drugs and investigate the mechanism of (5HT_2BR) activation by comprehending inter-residue interactions. The 5HT_2BR is a novel thread, and its role in reducing seizures in Dravet syndrome is emerging. The crystal structure (5HT_2BR) is a chimera with mutations; hence 3D-structure is modeled (4IB4: 5HT_2BR_M). The structure is cross-validated to simulate the human receptor using enrichment analysis (ROC: 0.79) and SAVESv6.0. Virtual screening of 2456 approved drugs yielded the best hits that are subjected to MM/GBSA and molecular dynamic (MD) simulations. The 2 top drugs Cabergoline (-53.44 kcal/mol) and Methylergonovine (-40.42 kcal/mol), display strong binding affinity, and ADMET/SAR analysis also suggests their non-mutagenic or non-carcinogenic nature. Methylergonovine has a weaker binding affinity and lower potency than standards [Ergotamine (agonist) and Methysergide (antagonist)] due to its higher K_i (1.32 M) and K_d (6.44 ×10^-8 M) values. Compared to standards, Cabergoline has moderate binding affinity and potency [K_i = 0.85 M and K_d = 5.53 × 10-8 M]. The top 2 drugs primarily interact with conserved residues (ASP135, LEU209, GLY221, ALA225, and THR140) as in agonists, unlike the antagonist. The top 2 drugs, upon binding to the 5HT_2BR_M, modify the helices VI, V, and III and shift the RMSD 2.48 Å and 3.07 Å. LEU209 forms a latch with residues 207-214 (forms a lid) in the 5HT_2BR_M receptor, which enhances agonist binding and prevents drug escape. Methylergonovine and Cabergoline interact more stongly with ALA225 than the antagonist. The post-MD analysis of Cabergoline suggests a better MM/GBSA value (-89.21 kcal/mol) than Methylergonovine (-63.54 kcal/mol). In this study, Cabergoline and Methylergonovine's agonistic mechanism and solid binding properties suggest their strong role in regulating the 5HT_2BR and might target drug-resistant epilepsy.

Zebrafish as an Innovative Tool for Epilepsy Modeling: State of the Art and Potential Future Directions

This article discusses the potential of Zebrafish (ZF) (Danio Rerio), as a model for epilepsy research. Epilepsy is a neurological disorder affecting both children and adults, and many aspects of this disease are still poorly understood. In vivo and in vitro models derived from rodents are the most widely used for studying both epilepsy pathophysiology and novel drug treatments. However, researchers have recently obtained several valuable insights into these two fields of investigation by studying ZF. Despite the relatively simple brain structure of these animals, researchers can collect large amounts of data in a much shorter period and at lower costs compared to classical rodent models. This is particularly useful when a large number of candidate antiseizure drugs need to be screened, and ethical issues are minimized. In ZF, seizures have been induced through a variety of chemoconvulsants, primarily pentylenetetrazol (PTZ), kainic acid (KA), and pilocarpine. Furthermore, ZF can be easily genetically modified to test specific aspects of monogenic forms of human epilepsy, as well as to discover potential convulsive phenotypes in monogenic mutants. The article reports on the state-of-the-art and potential new fields of application of ZF research, including its potential role in revealing epileptogenic mechanisms, rather than merely assessing iatrogenic acute seizure modulation.

A narrative review on traditional Chinese medicine prescriptions and bioactive components in epilepsy treatment

Background and Objective

In traditional Chinese medicine (TCM), natural drugs and their bioactive components have been widely used to treat epilepsy. Epilepsy is a chronic disease caused by abnormal discharge of brain neurons that leads to brain dysfunction and cognitive impairment. Several factors are involved in the mechanisms of epilepsy, and the current treatments do not seem promising. The potential efficacy of natural drugs with lower toxicity and less side effects have attracted increasing attention.

Methods

We used the terms, "TCM", "traditional Chinese medicine", "herbal", "epilepsy", "seizure", and the name of each prescription and bioactive components in the review to collect papers about application of TCM in epilepsy treatment from PubMed online database and Chinese database including Chinese National Knowledge Infrastructure (CNKI), Wanfang, and Weipu.

Key Content and Findings

We summarized some common TCM prescriptions and related active components used for the treatment of epilepsy. Six prescriptions (Chaihu Shugan decoction, Tianma Gouteng decoction, Kangxian capsules, Taohong Siwu decoction, Liujunzi decoction, Compound Danshen dropping pills) and nine main bioactive compounds (Saikosaponin A, Rhynchophylline, Tetramethylpyrazine, Gastrodin, Baicalin and baicalein, α-Asarone, Ginsenoside, Tanshinone, Paeoniflorin) were reviewed to provide a scientific basis for the development of potential antiepileptic drugs (AEDs).

Conclusions

The pharmacological effects and molecular mechanisms of TCM in the treatment of epilepsy are complex, targeting several pathological aspects of epilepsy. However, the limitations of TCM, such as the lack of standardized treatments, have prevented its clinical application in epilepsy treatment. Thus, additional clinical trials are required to further evaluate the effectiveness and safety of TCM prescriptions and their bioactive components in the future.

Tanshinone IIA enhances the ovarian reserve and attenuates ovarian oxidative stress in aged mice

Background

Tanshinone IIA (TSA), a major lipophilic component extracted from the roots of Salvia miltiorrhiza Bunge, has been widely used in China for its various biological activities. However, its effect on ovarian reserve in aged mice was not studied elsewhere.

Objectives

This study aimed to explore the effect of TSA on the ovarian reserve of aged mice as well as young mice. Forty weeks old mice (N = 40) were considered as aged group compared to 4 weeks old mice (N = 40), and these groups were subdivided into four subgroups (N = 10) to receive different doses of TSA (0, 10, 20, and 40 μg/g/day).

Methods

The effect of TSA was evaluated by counting follicular number by histological examination. Basal serum levels of FSH, LH, E2, and anti‐Mullerian hormone (AMH) were measured by ELISA. Moreover, the expression levels of antioxidant genes (CAT, Nrf2, GPX1), gap junction (Cx37), ERK1/2, and Smad5 family gene were examined at both mRNA (qPCR) and protein levels (western blot).

Results

Follicular number, level of AMH and E2, and the expression of CAT, Nrf2, and GPX1 genes increased significantly (p < 0.05) in aged mice administrated with medium (20 μg/g/day) and high (40 μg/g/day) doses of TSA, whereas FSH and LH levels were significantly low compared to low dose (10 μg/g/day) and control (0 μg/g/day) aged subgroups. However, we did not observe any effect of all doses of TSA on young mice.

Conclusions

Administration of TSA with medium and high doses up‐regulates the expression of antioxidative genes, reduces the oxidative injury, increases levels of AMH, and E2 levels that are relatively comparable to those in young mice, and consequently results in a healthy oocyte development.

Optimization of a locomotion-based zebrafish seizure model

BACKGROUND

Locomotor assays in zebrafish have emerged as a screening test in early drug discovery for antiseizure compounds. However, parameters differ considerably between published studies, which may explain some discrepant results with (candidate) antiseizure medications.

NEW METHOD

We optimized a locomotor-based seizure assay in zebrafish with pentylenetetrazol (PTZ) as the pharmacological proconvulsant to generate a therapeutic window in which proconvulsant-treated zebrafish larvae could be discriminated from a non-treated control. To generate a reliable control, exposure time and concentration of valproate (VPA, anticonvulsant) was optimized.

RESULTS

Wells with one or three larvae show a similar PTZ dose-dependent increase in locomotion with less variability in motility for the latter. Zebrafish immersed in 10 mM PTZ showed a significant increase in movement with a sustained effect, without any indication of toxicity. Animals treated with 3 mM VPA showed the strongest reduction of PTZ-induced movement without toxicity. The decrease in PTZ-induced locomotion was greater after 18 h versus 2 h.

COMPARISON WITH EXISTING METHOD(S)

For the larval zebrafish PTZ-induced seizure model, varying experimental parameters have been reported in literature. Our results show that PTZ is often used at toxic concentrations, and we provide instead reliable conditions to quantify convulsant behaviour using an infrared-beam motility assay.

CONCLUSIONS

We recommend using three zebrafish larvae per well to quantify locomotion in 96-multiwell plates. Larvae should preferably be exposed to 10 mM PTZ for 1 h, consisting of 30 min acclimation and 30 min subsequent recording. As positive control for anticonvulsant activity, we recommend exposure to 3 mM VPA for 18 h before administration of PTZ.

Use of Zebrafish Models to Boost Research in Rare Genetic Diseases

Rare genetic diseases are a group of pathologies with often unmet clinical needs. Even if rare by a single genetic disease (from 1/2000 to 1/more than 1,000,000), the total number of patients concerned account for approximatively 400 million peoples worldwide. Finding treatments remains challenging due to the complexity of these diseases, the small number of patients and the challenge in conducting clinical trials. Therefore, innovative preclinical research strategies are required. The zebrafish has emerged as a powerful animal model for investigating rare diseases. Zebrafish combines conserved vertebrate characteristics with high rate of breeding, limited housing requirements and low costs. More than 84% of human genes responsible for diseases present an orthologue, suggesting that the majority of genetic diseases could be modelized in zebrafish. In this review, we emphasize the unique advantages of zebrafish models over other in vivo models, particularly underlining the high throughput phenotypic capacity for therapeutic screening. We briefly introduce how the generation of zebrafish transgenic lines by gene-modulating technologies can be used to model rare genetic diseases. Then, we describe how zebrafish could be phenotyped using state-of-the-art technologies. Two prototypic examples of rare diseases illustrate how zebrafish models could play a critical role in deciphering the underlying mechanisms of rare genetic diseases and their use to identify innovative therapeutic solutions.

Opinion on the impact of non-monotonic dose responses on EFSA's human health risk assessments

This Opinion assesses the biological relevance of the non-monotonic dose responses (NMDR) identified in a previous EFSA External Report (Beausoleil et al., 2016) produced under GP/EFSA/SCER/2014/01 and the follow-up probabilistic assessment (Chevillotte et al., 2017a,b), focusing on the in vivo data sets fulfilling most of the checkpoints of the visual/statistical-based analysis identified in Beausoleil et al. (2016). The evaluation was completed with cases discussed in EFSA assessments and the update of the scientific literature. Observations of NMDR were confirmed in certain studies and are particularly relevant for receptor-mediated effects. Based on the results of the evaluation, the Opinion proposes an approach to be applied during the risk assessment process when apparent non-monotonicity is observed, also providing advice on specific elements to be considered to facilitate the assessment of NMDR in EFSA risk assessments. The proposed approach was applied to two case studies, Bisphenol A and bis(2-ethylhexyl phthalate (DEHP) and these evaluations are reported in dedicated annexes. Considering the potential impact of NMDRs in regulatory risk assessment, the Scientific Committee recommends a concerted international effort on developing internationally agreed guidance and harmonised frameworks for identifying and addressing NMDRs in the risk assessment process.

Effects of new antiseizure drugs on seizure activity and anxiety-like behavior in adult zebrafish

Several studies with larvae and adult zebrafish have shown that old and new antiseizure drugs (ASDs) produce discrepant results in seizure tests, locomotor activity or anxiety models. In this study, the pentylenetetrazole seizure test (PTZ) was performed to assess the effectiveness of four new ASDs: lamotrigine (LTG), topiramate (TPM), felbamate (FBM), and levetiracetam (LEV) in the subsequent stages of seizures in adult fish. All ASDs were administered intraperitoneally (i.p.). The time of maximal anticonvulsant effect and the dose-response relationship of the drugs were assessed. The effects of studied ASDs on the locomotor activity and the anxiety-like behavior in the color preference test were also investigated. Furthermore, drug concentrations in zebrafish homogenates were determined. LTG, TPM, and LEV significantly increased the seizure latency at three subsequent stages of seizures (SI-SIII), while FBM was effective only at SI. Locomotor activity decreased after TPM treatment. TPM and FBM exhibited a strong anxiolytic-like effect in the color preference test. LEV at the highest dose tested had a weak anxiolytic-like effect. The HPLC analysis showed average concentrations of the studied ASDs in the fish body during their maximum anticonvulsant activity. The present study shows that FBM cannot inhibit all subsequent PTZ seizure stages in the adult fish. Except for LTG, the studied drugs affected the anxiety-like behavior of treated animals. Furthermore, only TPM significantly changed locomotion parameters. Our findings support the need to accurately characterize the efficacy of new ASDs at different stages of the PTZ-induced seizures in adult zebrafish.

Positive Predictive Value Surfaces as a Complementary Tool to Assess the Performance of Virtual Screening Methods

BACKGROUND

Since their introduction in the virtual screening field, Receiver Operating Characteristic (ROC) curve-derived metrics have been widely used for benchmarking of computational methods and algorithms intended for virtual screening applications. Whereas in classification problems, the ratio between sensitivity and specificity for a given score value is very informative, a practical concern in virtual screening campaigns is to predict the actual probability that a predicted hit will prove truly active when submitted to experimental testing (in other words, the Positive Predictive Value - PPV). Estimation of such probability is however, obstructed due to its dependency on the yield of actives of the screened library, which cannot be known a priori.

OBJECTIVE

To explore the use of PPV surfaces derived from simulated ranking experiments (retrospective virtual screening) as a complementary tool to ROC curves, for both benchmarking and optimization of score cutoff values.

METHODS

The utility of the proposed approach is assessed in retrospective virtual screening experiments with four datasets used to infer QSAR classifiers: inhibitors of Trypanosoma cruzi trypanothione synthetase; inhibitors of Trypanosoma brucei N-myristoyltransferase; inhibitors of GABA transaminase and anticonvulsant activity in the 6 Hz seizure model.

RESULTS

Besides illustrating the utility of PPV surfaces to compare the performance of machine learning models for virtual screening applications and to select an adequate score threshold, our results also suggest that ensemble learning provides models with better predictivity and more robust behavior.

CONCLUSION

PPV surfaces are valuable tools to assess virtual screening tools and choose score thresholds to be applied in prospective in silico screens. Ensemble learning approaches seem to consistently lead to improved predictivity and robustness.

A zebrafish-centric approach to antiepileptic drug development

Danio rerio (zebrafish) are a powerful experimental model for genetic and developmental studies. Adaptation of zebrafish to study seizures was initially established using the common convulsant agent pentylenetetrazole (PTZ). Larval PTZ-exposed zebrafish exhibit clear behavioral convulsions and abnormal electrographic activity, reminiscent of interictal and ictal epileptiform discharge. By using this model, our laboratory developed simple locomotion-based and electrophysiological assays to monitor and quantify seizures in larval zebrafish. Zebrafish also offer multiple advantages for rapid genetic manipulation and high-throughput phenotype-based drug screening. Combining these seizure assays with genetically modified zebrafish that represent Dravet syndrome, a rare genetic epilepsy, ultimately contributed to a phenotype-based screen of over 3500 drugs. Several drugs identified in these zebrafish screens are currently in clinical or compassionate-use trials. The emergence of this 'aquarium-to-bedside' approach suggests that broader efforts to adapt and improve upon this zebrafish-centric strategy can drive a variety of exciting new discoveries.

Schaftoside Suppresses Pentylenetetrazol-Induced Seizures in Zebrafish via Suppressing Apoptosis, Modulating Inflammation, and Oxidative Stress

The lack of disease-modifying therapeutic strategies against epileptic seizures has caused a surge in preclinical research focused on exploring and developing novel therapeutic candidates for epilepsy. Compounds from traditional Chinese medicines (TCMs) have gained much attention for a plethora of neurological diseases, including epilepsy. Herein, for the first time, we evaluated the anticonvulsive effects of schaftoside (SS), a TCM, on pentylenetetrazol (PTZ)-induced epileptic seizures in zebrafish and examined the underlying mechanisms. We observed that SS pretreatments significantly suppressed seizure-like behavior and prolonged the onset of seizures. Zebrafish larvae pretreated with SS demonstrated downregulation of c-fos expression during seizures. PTZ-induced upregulation of apoptotic cells was decreased upon pretreatment with SS. Inflammatory phenomena during seizure progression including the upregulation of interleukin 6 (IL-6), interleukin 1 beta (IL-1β), and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) were downregulated upon pretreatment with SS. The PTZ-induced recruitment of immunocytes was in turn reduced upon SS pretreatment. Moreover, SS pretreatment modulated oxidative stress, as demonstrated by decreased levels of catalase (CAT) and increased levels of glutathione peroxidase-1a (GPx1a) and manganese superoxide dismutase (Mn-SOD). However, pretreatment with SS modulated the PTZ-induced downregulation of the relative enzyme activity of CAT, GPx, and SOD. Hence, our findings suggest that SS pretreatment ameliorates PTZ-induced seizures, suppresses apoptosis, and downregulates the inflammatory response and oxidative stress, which potentially protect against further seizures in zebrafish.

A Pharmacological Perspective on Plant-derived Bioactive Molecules for Epilepsy

Epilepsy is a related chronic neurological condition of a predisposition for recurrent epileptic seizures, with various manifestations and causes. Although there are antiepileptic drugs, complementary natural therapies are widely used. The purpose of this systematic review was to analyze the antiepileptic/anticonvulsant pharmacological properties of plant-food derived bioactive molecules. In this regard, a systematic review of the PubMed database was made based on the inclusion criteria. Natural compounds/herbs with scientifically proven antiepileptic properties were selected. Experimental pharmacological studies in vitro and in vivo have shown that flavonoids, alkaloids and terpenoids may have anticonvulsant mechanisms similar to the new generation antiepileptic drugs. The relationships of structure-anticonvulsant effect, pharmacological models, seizure-inducing factors and response, effective dose were also analyzed and discussed. The results of in vitro and in vivo pharmacological studies analyzed in this systematic review support the clinical importance of plant-food-derived bioactive molecules for the complementary treatment of epilepsy. Thus, are opened new perspectives to develop new natural anticonvulsant drugs.

Comparison of the chronic toxicities of graphene and graphene oxide toward adult zebrafish by using biochemical and phenomic approaches

Graphene (GR) and graphene oxide (GO) are widely being used as promising candidates for biomedical applications, as well as for bio-sensing, drug delivery, and anticancer therapy. However, their undesirable side effects make it necessary to assess further the toxicity and safety of using these materials. The main objective of the current study was to investigate the toxicities of GR and GO in predicted environmental relevant concentrations in adult zebrafish (Danio rerio), particularly on their behaviors, and conducted biochemical assays to elucidate the possible mechanism that underlies their toxicities. Zebrafish was chronically (∼14 days) exposed to two different doses of GR (0.1 and 0.5 ppm) or GO (0.1 and 1 ppm). At 14 ± 1 days, a battery of behavioral tests was conducted, followed by enzyme-linked immunosorbent assays (ELISA) test on the following day to inspect the alterations in antioxidant activity, oxidative stress, and neurotransmitters in the treated zebrafish brain. An alteration in predator avoidance behavior was observed in all treated groups, while GR-treated fish exhibited abnormal exploratory behavior. Furthermore, altered locomotor activity was displayed by most of the treated groups, except for the high concentration of the GR group. From the ELISA results, we discovered a high concentration of GR exposure significantly decreased several neurotransmitters and cortisol levels. Meanwhile, elevated reactive oxygen species (ROS) were displayed by the group treated with low and high doses of GR and GO, respectively. These significant changes would possibly affect zebrafish behaviors and might suggest the potential toxicity from GR and GO exposures. To sum up, the present study presented new evidence for the effects of GR and GO in zebrafish behavioral dysregulation. We hope these assessments can contribute to our understanding of graphene and graphene oxide biosafety.

Identification of Potential Antiseizure Agents in Boswellia sacra using In Vivo Zebrafish and Mouse Epilepsy Models

The resin of the tree Boswellia sacra Flueck. (synonym: B. carterii; Burseraceae), also known as "frankincense", is a traditional remedy used for central nervous system disorders in East Africa. Here we report the evaluation of its antiseizure activity in zebrafish and mouse epilepsy models to identify novel antiseizure compounds. The resin was extracted by solvents of increasing polarity. The hexane extract demonstrated the strongest antiseizure activity and was therefore subjected to bioactivity-guided isolation, which leaded to the isolation of eight terpene derivatives. A new prenylbicyclogermacrene derivative (2) was isolated along with seven other compounds (1, 3-8). Among them, the triterpene β-boswellic acid (5) showed the strongest activity and reduced 90% of pentylenetetrazole (PTZ)-induced seizures at 100 μg/mL. In parallel to B. sacra, a commercial extract of Boswellia serrata was also evaluated and showed moderate bioactivity (45% reduction at 30 μg/mL). The extract of B. serrata was subjected to targeted isolation of other boswellic acid derivatives (9-13), which were evaluated for antiseizure activity in comparison with 5. In the whole series, β-boswellic acid (5) was the most active (60% reduction at 200 μM), and its potency was also confirmed with its purchased standard (S5). Pure nanoparticles of S5 and a commercially formulated extract of B. serrata were tested in a PTZ-kindling mouse seizure model. This notably revealed that the S5 administration reduced seizures by 50% in this mouse model, which was consistent with its detection and quantification in plasma and brain samples. This study and the preclinical evaluation performed indicate that β-boswellic acid, common to various species of Boswellia, has some potential as an antiseizure agent.

Tanshinone IIA: A phytochemical as a promising drug candidate for neurodegenerative diseases

Tanshinones, lipophilic diterpenes isolated from the rhizome of Salvia miltiorrhiza, have diverse pharmacological activities against human ailments including neurological diseases. In fact, tanshinones have been used to treat heart diseases, stroke, and vascular diseases in traditional Chinese medicine. During the last decade, tanshinones have been the most widely studied phytochemicals for their neuroprotective effects against experimental models of cerebral ischemia and Alzheimer's diseases. Importantly, tanshinone IIA, mostly studied tanshinone for biological activities, is recently reported to attenuate blood-brain barrier permeability among stroke patients, suggesting tanshinone IIA as an appealing therapeutic candidate for neurological diseases. Tanshinone I and IIA are also effective in experimental models of Parkinson's disease, Multiple sclerosis, and other neuroinflammatory diseases. In addition, several experimental studies suggested the pleiotropic neuroprotective effects of tanshinones such as anti-inflammatory, antioxidant, anti-apoptotic, and BBB protectant further value aiding to tanshinone as an appealing therapeutic strategy in neurological diseases. Therefore, in this review, we aimed to compile the recent updates and cellular and molecular mechanisms of neuroprotection of tanshinone IIA in diverse neurological diseases.

An ecotoxicological approach to microplastics on terrestrial and aquatic organisms: A systematic review in assessment, monitoring and biological impact

Marine and land plastic debris biodegrades at micro- and nanoscales through progressive fragmentation. Oceanographic model studies confirm the presence of up to ∼2.41 million tons of microplastics across the Atlantic, Pacific, and Indian subtropical gyres. Microplastics distribute from primary (e.g., exfoliating cleansers) and secondary (e.g., chemical deterioration) sources in the environment. This anthropogenic phenomenon poses a threat to the flora and fauna of terrestrial and aquatic ecosystems as ingestion and entanglement cases increase over time. This review focuses on the impact of microplastics across taxa at suggested environmentally relevant concentrations, and advances the groundwork for future ecotoxicological-based research on microplastics including the main points: (i) adhesion of chemical pollutants (e.g., PCBs); (ii) biological effects (e.g., bioaccumulation, biomagnification, biotransportation) in terrestrial and aquatic organisms; (iii) physico-chemical properties (e.g., polybrominated diphenyl ethers) and biodegradation pathways in the environment (e.g., chemical stress, heat stress); and (iv) an ecotoxicological prospect for optimized impact assessments.

Neuro-nutraceutical potential of Asparagus racemosus: A review

Debilitating neuropsychiatric and neurodegenerative conditions are associated with complex multifactorial pathophysiology. Their treatment strategies often only provide symptomatic relief, delaying disease progression without giving a complete cure. Potent and safer treatment alternatives beyond symptomatic relief are sought. Herbal supplements have surely been explored due to their multiple component nature to enhance the effect of western medications. One such well-documented nutraceutical in the ancient Greek, Chinese, and Ayurvedic medicine system known for its various medicinal benefits is Asparagus racemosus. Widely used for its lactogenic properties, A. racemosus is also cited in Ayurveda as a nervine tonic. A. racemosus based nutraceuticals have shown to possess adaptogenic, neuroprotective, antioxidant, anti-inflammatory, and nootropic activity under preclinical and clinical settings without posing significant adverse effects. A. racemosus extracts restore the perturbed neurotransmitters and prevent oxidative neuronal damage. From the available neuropharmacological researches, the physiological actions of A. racemosus can ultimately be directed for either augmentation of cognitive ability or in the management of neurological conditions such as stress, anxiety, depression, epilepsy, Parkinson's, and Alzheimer's disease. The studies focus on the multi-component extract, and the lack of standardization has been a major hurdle in preventing the allotment of reported neuropharmacological activity to one of the phytoconstituent. Herbal standardization of the plant extract based on a specific biomarker can help elucidate the intricate biomolecular pathway and neurocircuitries being involved. This, followed by rigorous standardized clinical trials, fixing dosages, and determining contraindications would facilitate the translation of A. racemosus to a FDA-approved neuromedicine for neurological disorders.

Natural Medicines for the Treatment of Epilepsy: Bioactive Components, Pharmacology and Mechanism

Epilepsy is a chronic disease that can cause temporary brain dysfunction as a result of sudden abnormal discharge of the brain neurons. The seizure mechanism of epilepsy is closely related to the neurotransmitter imbalance, synaptic recombination, and glial cell proliferation. In addition, epileptic seizures can lead to mitochondrial damage, oxidative stress, and the disorder of sugar degradation. Although the mechanism of epilepsy research has reached up to the genetic level, the presently available treatment and recovery records of epilepsy does not seem promising. Recently, natural medicines have attracted more researches owing to their low toxicity and side-effects as well as the excellent efficacy, especially in chronic diseases. In this study, the antiepileptic mechanism of the bioactive components of natural drugs was reviewed so as to provide a reference for the development of potential antiepileptic drugs. Based on the different treatment mechanisms of natural drugs considered in this review, it is possible to select drugs clinically. Improving the accuracy of medication and the cure rate is expected to compensate for the shortage of the conventional epilepsy treatment drugs.

Anti-High Mobility Group Box-1 Monoclonal Antibody Attenuates Seizure-Induced Cognitive Decline by Suppressing Neuroinflammation in an Adult Zebrafish Model

Epilepsy is a chronic brain disease afflicting around 70 million global population and is characterized by persisting predisposition to generate epileptic seizures. The precise understanding of the etiopathology of seizure generation is still elusive, however, brain inflammation is considered as a major contributor to epileptogenesis. HMGB1 protein being an initiator and crucial contributor of inflammation is known to contribute significantly to seizure generation via activating its principal receptors namely RAGE and TLR4 reflecting a potential therapeutic target. Herein, we evaluated an anti-seizure and memory ameliorating potential of an anti-HMGB1 monoclonal antibody (mAb) (1, 2.5 and 5 mg/kg, I.P.) in a second hit Pentylenetetrazol (PTZ) (80 mg/kg, I.P.) induced seizure model earlier stimulated with Pilocarpine (400 mg/kg, I.P.) in adult zebrafish. Pre-treatment with anti-HMGB1 mAb dose-dependently lowered the second hit PTZ-induced seizure but does not alter the disease progression. Moreover, anti-HMGB1 mAb also attenuated the second hit Pentylenetetrazol induced memory impairment in adult zebrafish as evidenced by an increased inflection ration at 3 and 24 h trail in T-maze test. Besides, decreased level of GABA and an upregulated Glutamate level was observed in the second hit PTZ induced group, which was modulated by pre-treatment with anti-HMGB1 mAb. Inflammatory responses occurred during the progression of seizures as evidenced by upregulated mRNA expression of HMGB1, TLR4, NF-κB, and TNF-α, in a second hit PTZ group, which was in-turn downregulated upon pre-treatment with anti-HMGB1 mAb reflecting its anti-inflammatory potential. Anti-HMGB1 mAb modulates second hit PTZ induced changes in mRNA expression of CREB-1 and NPY. Our findings indicates anti-HMGB1 mAb attenuates second hit PTZ-induced seizures, ameliorates related memory impairment, and downregulates the seizure induced upregulation of inflammatory markers to possibly protect the zebrafish from the incidence of further seizures through via modulation of neuroinflammatory pathway.

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.

Effects of classic antiseizure drugs on seizure activity and anxiety-like behavior in adult zebrafish

The zebrafish is extensively used as a model organism for studying several disorders of the central nervous system (CNS), including epilepsy. Some antiseizure drugs (ASDs) have been shown to produce discrepant results in larvae and adults zebrafish, therefore, their anticonvulsant efficacy in subsequent stages of the pentylenetetrazole (PTZ)-induced seizures should be more precisely characterized. The purpose of this study was to investigate behavioral effects of five classic ASDs: valproate (VPA), phenytoin (PHT), carbamazepine (CBZ), diazepam (DZP), and phenobarbital (PB) administered intraperitoneally (i.p.) in the PTZ-induced seizure test in adult zebrafish. We determined the time of maximal effect and the dose-response relationship of the studied ASDs. Furthermore, we assessed changes in the locomotor activity and the anxiety-like behavior in the color preference test. Moreover, drug concentrations in zebrafish homogenates were examined. VPA, DZP, and PB significantly increased the seizure latency at three subsequent stages of seizures (SI-SIII). PHT produced the anticonvulsant-like effect at SI and SII, while CBZ was effective at SII and SIII. Only DZP decreased zebrafish locomotor activity. A strong anxiolytic-like effect was observed after administration of PHT and PB. A weak anxiolytic-like effect occurred after treatment with VPA and DZP. The HPLC analysis showed the average concentrations of the studied ASDs in the fish body during the maximum anticonvulsant activity of each drug. Our results confirm the advantages of using zebrafish with the mature CNS over larval models and its utility to investigate some neuropharmacological properties of the tested drugs.

Tanshinone IIA: A Review of its Anticancer Effects

Tanshinone IIA (Tan IIA) is a pharmacologically lipophilic active constituent isolated from the roots and rhizomes of the Chinese medicinal herb Salvia miltiorrhiza Bunge (Danshen). Tan IIA is currently used in China and other neighboring countries to treat patients with cardiovascular system, diabetes, apoplexy, arthritis, sepsis, and other diseases. Recently, it was reported that tan IIA could have a wide range of antitumor effects on several human tumor cell lines, but the research of the mechanism of tan IIA is relatively scattered in cancer. This review aimed to summarize the recent advances in the anticancer effects of tan IIA and to provide a novel perspective on clinical use of tan IIA.

Norditerpenoids with Selective Anti-Cholinesterase Activity from the Roots of Perovskia atriplicifolia Benth

Inhibition of cholinesterases remains one of a few available treatment strategies for neurodegenerative dementias such as Alzheimer’s disease and related conditions. The current study was inspired by previous data on anticholinesterase properties of diterpenoids from Perovskia atriplicifolia and other Lamiaceae species. The acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibition by the three new natural compounds—(1R,15R)-1-acetoxycryptotanshinone (1), (1R)-1-acetoxytanshinone IIA (2), and (15R)-1-oxoaegyptinone A (3)—as well as, new for this genus, isograndifoliol (4) were assessed. Three of these compounds exhibited profound inhibition of butyrylcholinesterase (BChE) and much weaker inhibition of acetylcholinesterase (AChE). All compounds (1–4) selectively inhibited BChE (IC₅₀ = 2.4, 7.9, 50.8, and 0.9 µM, respectively), whereas only compounds 3 and 4 moderately inhibited AChE (IC₅₀ 329.8 µM and 342.9 µM). Molecular docking and in silico toxicology prediction studies were also performed on the active compounds. Natural oxygenated norditerpenoids from the traditional Central Asian medicinal plant P. atriplicifolia are selective BChE inhibitors. Their high potential makes them useful candidate molecules for further investigation as lead compounds in the development of a natural drug against dementia caused by neurodegenerative diseases.

Seizing the moment: Zebrafish epilepsy models

Zebrafish are now widely accepted as a valuable animal model for a number of different central nervous system (CNS) diseases. They are suitable both for elucidating the origin of these disorders and the sequence of events culminating in their onset, and for use as a high-throughput in vivo drug screening platform. The availability of powerful and effective techniques for genome manipulation allows the rapid modelling of different genetic epilepsies and of conditions with seizures as a core symptom. With this review, we seek to summarize the current knowledge about existing epilepsy/seizures models in zebrafish (both pharmacological and genetic) and compare them with equivalent rodent and human studies. New findings obtained from the zebrafish models are highlighted. We believe that this comprehensive review will highlight the value of zebrafish as a model for investigating different aspects of epilepsy and will help researchers to use these models to their full extent.

The Influence of Palmatine Isolated from Berberis sibirica Radix on Pentylenetetrazole-Induced Seizures in Zebrafish

Palmatine (PALM) and berberine (BERB) are widely identified isoquinoline alkaloids among the representatives of the Berberidaceae botanical family. The antiseizure activity of BERB was shown previously in experimental epilepsy models. We assessed the effect of PALM in a pentylenetetrazole (PTZ)-induced seizure assay in zebrafish, with BERB as an active reference compound. Both alkaloids were isolated from the methanolic root extract of Berberis sibirica by counter-current chromatography, and their ability to cross the blood–brain barrier was determined via quantitative structure–activity relationship assay. PALM exerted antiseizure activity, as confirmed by electroencephalographic analysis, and decreased c-fos and bdnf levels in PTZ-treated larvae. In a behavioral assay, PALM dose-dependently decreased PTZ-induced hyperlocomotion. The combination of PALM and BERB in ED₁₆ doses revealed hyperadditive activity towards PTZ-induced hyperlocomotion. Notably, we have indicated that both alkaloids may exert their anticonvulsant activity through different mechanisms of action. Additionally, the combination of both alkaloids in a 1:2.17 ratio (PALM: BERB) mimicked the activity of the pure extract, which indicates that these two active compounds are responsible for its anticonvulsive activity. In conclusion, our study reveals for the first time the anticonvulsant activity of PALM and suggests the combination of PALM and BERB may have higher therapeutic value than separate usage of these compounds.

Tanshinone IIA enhances the inhibitory effect of imatinib on proliferation and motility of acute leukemia cell line TIB‑152 in vivo and in vitro by inhibiting the PI3K/AKT/mTOR signaling pathway

Acute lymphoblastic leukemia (ALL) is a malignant hematological disease. Tanshinone IIA (Tan IIA) has antitumor activity in vitro and in vivo. The aim of the present study was to investigate the effects of Tan IIA in combination with imatinib (IM) on the proliferation, apoptosis, migration and invasion of acute T lymphocytic leukemia TIB‑152 cells in vivo and in vitro, and analyze the potential underlying mechanism. Tan IIA and IM, alone and in combination, significantly inhibited proliferation, migration and invasion of TIB‑152 cells, and promoted apoptosis; the effect of co‑treatment with Tan IIA plus IM was enhanced. IGF‑1 promoted the proliferation, migration and invasion of TIB‑152 cells and inhibited apoptosis, while Tan IIA treatment significantly reversed these effects. In vivo experiments demonstrated that treatment with Tan IIA and IM, alone or in combination, significantly inhibited tumor growth in TIB‑152 xenograft mice; the growth inhibition of Tan IIA plus IM was the strongest observed. Western blot analysis revealed that the combination of Tan IIA and IM resulted in significantly lower levels of p‑PI3K, p‑AKT and p‑mTOR in cells and tissues compared with the IM and Tan alone treatment groups. In addition, the combination of Tan IIA and IM significantly decreased the levels of Ki67, cleaved caspase‑3, VEGF and MMP‑9 in cells and tissues, and the level of caspase‑3 was significantly increased. Taken together, the results revealed that Tan IIA enhanced the inhibitory effect of imatinib on TIB‑152 cell proliferation, migration and invasion, and induced apoptosis, which may be associated with inhibition of the PI3K/AKT/mTOR signaling pathway.

N-Benzyl-(2,5-dioxopyrrolidin-1-yl)propanamide (AS-1) with Hybrid Structure as a Candidate for a Broad-Spectrum Antiepileptic Drug

In our recent studies, we identified compound N-benzyl-2-(2,5-dioxopyrrolidin-1-yl)propanamide (AS-1) as a broad-spectrum hybrid anticonvulsant which showed potent protection across the most important animal acute seizure models such as the maximal electroshock (MES) test, the subcutaneous pentylenetetrazole (s.c. PTZ) test, and the 6-Hz (32 mA) test in mice. Therefore, AS-1 may be recognized as a candidate for new anticonvulsant effective in different types of human epilepsy with a favorable safety margin profile determined in the rotarod test in mice. In the aim of further pharmacological evaluation of AS-1, in the current study, we examined its activity in the 6-Hz (44 mA) test, which is known as the model of drug-resistant epilepsy. Furthermore, we determined also the antiseizure activity in the kindling model of epilepsy induced by repeated injection of pentylenetetrazole (PTZ) in mice. As a result, AS-1 revealed relatively potent protection in the 6-Hz (44 mA) test, as well as delayed the progression of kindling induced by repeated injection of PTZ in mice at doses of 15 mg/kg, 30 mg/kg, and 60 mg/kg. Importantly, the isobolographic analysis showed that a combination of AS-1 and valproic acid (VPA) at the fixed ratio of 1:1 displayed a supra-additive (synergistic) interaction against PTZ-induced seizures in mice. Thus, AS-1 may be potentially used in an add-on therapy with VPA. Moreover, incubation of zebrafish larvae with AS-1 substantially decreased the number, cumulative but not the mean duration of epileptiform-like events in electroencephalographic assay. Finally, the in vitro ADME-Tox studies revealed that AS-1 is characterized by a very good permeability in the parallel artificial membrane permeability assay test, excellent metabolic stability on human liver microsomes (HLMs), no significant influence on CYP3A4/CYP2D6 activity, and moderate inhibition of CYP2C9 in a concentration of 10 μM, as well as no hepatotoxic properties in HepG2 cells (concentration of 10 μM).

Zebrafish-Based Discovery of Antiseizure Compounds from the North Sea: Isoquinoline Alkaloids TMC-120A and TMC-120B

There is a high need for the development of new and improved antiseizure drugs (ASDs) to treat epilepsy. Despite the potential of marine natural products (MNPs), the EU marine biodiscovery consortium PharmaSea has made the only effort to date to perform ASD discovery based on large-scale screening of MNPs. To this end, the embryonic zebrafish photomotor response assay and the larval zebrafish pentylenetetrazole (PTZ) model were used to screen MNP extracts for neuroactivity and antiseizure activity, respectively. Here we report the identification of the two known isoquinoline alkaloids TMC-120A and TMC-120B as novel antiseizure compounds, which were isolated by bioactivity-guided purification from the marine-derived fungus Aspergillus insuetus. TMC-120A and TMC-120B were observed to significantly lower PTZ-induced seizures and epileptiform brain activity in the larval zebrafish PTZ seizure model. In addition, their structural analogues TMC-120C, penicisochroman G, and ustusorane B were isolated and also significantly lowered PTZ-induced seizures. Finally, TMC-120A and TMC-120B were investigated in a mouse model of drug-resistant focal seizures. Compound treatment significantly shortened the seizure duration, thereby confirming their antiseizure activity. These data underscore the possibility to translate findings in zebrafish to mice in the field of epilepsy and the potential of the marine environment for ASD discovery.

Zebrafish as an Emerging Model for Bioassay-Guided Natural Product Drug Discovery for Neurological Disorders

Most neurodegenerative diseases are currently incurable, with large social and economic impacts. Recently, there has been renewed interest in investigating natural products in the modern drug discovery paradigm as novel, bioactive small molecules. Moreover, the discovery of potential therapies for neurological disorders is challenging and involves developing optimized animal models for drug screening. In contemporary biomedicine, the growing need to develop experimental models to obtain a detailed understanding of malady conditions and to portray pioneering treatments has resulted in the application of zebrafish to close the gap between in vitro and in vivo assays. Zebrafish in pharmacogenetics and neuropharmacology are rapidly becoming a widely used organism. Brain function, dysfunction, genetic, and pharmacological modulation considerations are enhanced by both larval and adult zebrafish. Bioassay-guided identification of natural products using zebrafish presents as an attractive strategy for generating new lead compounds. Here, we see evidence that the zebrafish's central nervous system is suitable for modeling human neurological disease and we review and evaluate natural product research using zebrafish as a vertebrate model platform to systematically identify bioactive natural products. Finally, we review recently developed zebrafish models of neurological disorders that have the potential to be applied in this field of research.

Identification of GSK-3 as a Potential Therapeutic Entry Point for Epilepsy

In view of the clinical need for new antiseizure drugs (ASDs) with novel modes of action, we used a zebrafish seizure model to screen the anticonvulsant activity of medicinal plants used by traditional healers in the Congo for the treatment of epilepsy, and identified a crude plant extract that inhibited pentylenetetrazol (PTZ)-induced seizures in zebrafish larvae. Zebrafish bioassay-guided fractionation of this anticonvulsant Fabaceae species, Indigofera arrecta, identified indirubin, a compound with known inhibitory activity of glycogen synthase kinase (GSK)-3, as the bioactive component. Indirubin, as well as the more potent and selective GSK-3 inhibitor 6-bromoindirubin-3'-oxime (BIO-acetoxime) were tested in zebrafish and rodent seizure assays. Both compounds revealed anticonvulsant activity in PTZ-treated zebrafish larvae, with electroencephalographic recordings revealing reduction of epileptiform discharges. Both indirubin and BIO-acetoxime also showed anticonvulsant activity in the pilocarpine rat model for limbic seizures and in the 6-Hz refractory seizure mouse model. Most interestingly, BIO-acetoxime also exhibited anticonvulsant actions in 6-Hz fully kindled mice. Our findings thus provide the first evidence for anticonvulsant activity of GSK-3 inhibition, thereby implicating GSK-3 as a potential therapeutic entry point for epilepsy. Our results also support the use of zebrafish bioassay-guided fractionation of antiepileptic medicinal plant extracts as an effective strategy for the discovery of new ASDs with novel mechanisms of action.

Network Properties Revealed during Multi-Scale Calcium Imaging of Seizure Activity in Zebrafish

Seizures are characterized by hypersynchronization of neuronal networks. Understanding these networks could provide a critical window for therapeutic control of recurrent seizure activity, i.e., epilepsy. However, imaging seizure networks has largely been limited to microcircuits in vitro or small “windows” in vivo. Here, we combine fast confocal imaging of genetically encoded calcium indicator (GCaMP)-expressing larval zebrafish with local field potential (LFP) recordings to study epileptiform events at whole-brain and single-neuron levels in vivo. Using an acute seizure model (pentylenetetrazole, PTZ), we reliably observed recurrent electrographic ictal-like events associated with generalized activation of all major brain regions and uncovered a well-preserved anterior-to-posterior seizure propagation pattern. We also examined brain-wide network synchronization and spatiotemporal patterns of neuronal activity in the optic tectum microcircuit. Brain-wide and single-neuronal level analysis of PTZ-exposed and 4-aminopyridine (4-AP)-exposed zebrafish revealed distinct network dynamics associated with seizure and non-seizure hyperexcitable states, respectively. Neuronal ensembles, comprised of coactive neurons, were also uncovered during interictal-like periods. Taken together, these results demonstrate that macro- and micro-network calcium motifs in zebrafish may provide a greater understanding of epilepsy.

Identification of fukinolic acid from Cimicifuga heracleifolia and its derivatives as novel antiviral compounds against enterovirus A71 infection

Human enterovirus 71 (EV-A71) infections cause a wide array of diseases ranging from diarrhoea and rashes to hand-foot-and-mouth disease and, in rare cases, severe neurological disorders. No specific antiviral drug therapy is currently available. Extracts from 75 Chinese medicinal plants selected for antiviral activity based on the Chinese pharmacopeia and advice from traditional Chinese medicine clinicians were tested for activity against EV-A71. The aqueous extract of the rhizome of Cimicifuga heracleifolia (Sheng Ma) and Arnebia euchroma (Zi Cao) showed potent antiviral activity. The active fractions were isolated by bioassay-guided purification, and identified by a combination of high-resolution mass spectrometry and nuclear magnetic resonance. Fukinolic acid and cimicifugic acid A and J, were identified as active anti-EV-A71 compounds for C. heracleifolia, whereas for A. euchroma, two caffeic acid derivatives were tentatively deduced. Commercially available fukinolic acid analogues such as L-chicoric acid and D-chicoric also showed in vitro micromolar activity against EV-A71 lab-strain and clinical isolates.

Anticonvulsant Activity of Pterostilbene in Zebrafish and Mouse Acute Seizure Tests

Pterostilbene (PTE), a natural dimethylated analog of resveratrol, possesses numerous health-beneficial properties. The ability of PTE to cross the blood–brain barrier raised the possibility that this compound may modulate central nervous system functions, including seizure activity. The aim of our study was to investigate the activity of PTE in the larval zebrafish pentylenetetrazole (PTZ) seizure assay and three acute seizure tests in mice, i.e., in the maximal electroshock seizure threshold (MEST), 6 Hz-induced psychomotor seizure threshold and intravenous (iv) PTZ tests. Additionally, potential antidepressant activity of PTE was estimated in the forced swim test in mice. The chimney test was used to determine the influence of PTE on motor coordination in mice, while its influence on neuromuscular strength was assessed in the grip strength test in mice. Locomotor activity was determined to verify the results from the forced swim test. PTE revealed an evident anticonvulsant effect both in zebrafish larvae (10 µM; 2 h-incubation) and mice (at doses of 100 and 200 mg/kg, intraperitoneally) but it did not exhibit antidepressant potential in the forced swim test. Furthermore, it did not cause any statistically significant changes in motor coordination, neuromuscular strength and locomotor activity in mice. In conclusion, our present findings demonstrate for the first time the anticonvulsant potential of PTE. The aforementioned results suggest that it might be employed in epilepsy treatment, however, further precise studies are required to verify its activity in other experimental seizure and epilepsy models and its precise mechanism of action should be determined.

Multigenerational consequences of early-life cannabinoid exposure in zebrafish

While Δ⁹-tetrahydrocannabinol (THC) has been widely studied in the realm of developmental and reproductive toxicology, few studies have investigated potential toxicities from a second widely used cannabis constituent, cannabidiol (CBD). CBD is popularized for its therapeutic potential for reducing seizure frequencies in epilepsy. This study investigated developmental origins of health and disease (DOHaD) via multigenerational gene expression patterns, behavior phenotypes, and reproductive fitness of a subsequent F1 following an F0 developmental exposure of zebrafish (Danio rerio) to THC (0.024, 0.12, 0.6 mg/L; 0.08, 0.4, 2 μM) or CBD (0.006, 0.03, 0.15 mg/L; 0.02, 0.1, 0.5 μM). Embryonic exposure at these concentrations did not cause notable morphological abnormalities in either F0 or F1 generations. However, during key developmental stages (14, 24, 48, 72, and 96 h post fertilization) THC and CBD caused differential expression of c-fos, brain-derived neurotrophic factor (bdnf), and deleted-in-azoospermia like (dazl), while in F1 larvae only CBD differentially expressed dazl. Larval photomotor behavior was reduced (F0) or increased (F1) by THC exposure, while CBD had no effect on F0 larvae, but decreased activity in the unexposed F1 larvae. These results support our hypothesis of cannabinoid-related developmental neurotoxicity. As adults, F0 fecundity was reduced, but it was not in F1 adults. Conversely, in the adult open field test there were no significant effects in F0 fish, but a significant reduction in the time in periphery was seen in F1 fish from the highest THC exposure group. The results highlight the need to consider long-term ramifications of early-life exposure to cannabinoids.

Zebrafish-Based Discovery of Antiseizure Compounds from the Red Sea: Pseurotin A2 and Azaspirofuran A

In search for novel antiseizure drugs (ASDs), the European FP7-funded PharmaSea project used zebrafish embryos and larvae as a drug discovery platform to screen marine natural products to identify promising antiseizure hits in vivo for further development. Within the framework of this project, seven known heterospirocyclic γ-lactams, namely, pseurotin A, pseurotin A₂, pseurotin F1, 11- O-methylpseurotin A, pseurotin D, azaspirofuran A, and azaspirofuran B, were isolated from the bioactive marine fungus Aspergillus fumigatus, and their antiseizure activity was evaluated in the larval zebrafish pentylenetetrazole (PTZ) seizure model. Pseurotin A₂ and azaspirofuran A were identified as antiseizure hits, while their close chemical analogues were inactive. Besides, electrophysiological analysis from the zebrafish midbrain demonstrated that pseurotin A₂ and azaspirofuran A also ameliorate PTZ-induced epileptiform discharges. Next, to determine whether these findings translate to mammalians, both compounds were analyzed in the mouse 6 Hz (44 mA) psychomotor seizure model. They lowered the seizure duration dose-dependently, thereby confirming their antiseizure properties and suggesting activity against drug-resistant seizures. Finally, in a thorough ADMET assessment, pseurotin A₂ and azaspirofuran A were found to be drug-like. Based on the prominent antiseizure activity in both species and the drug-likeness, we propose pseurotin A₂ and azaspirofuran A as lead compounds that are worth further investigation for the treatment of epileptic seizures. This study not only provides the first evidence of antiseizure activity of pseurotins and azaspirofurans, but also demonstrates the value of the zebrafish model in (marine) natural product drug discovery in general, and for ASD discovery in particular.

The Use of Larval Zebrafish (Danio rerio) Model for Identifying New Anxiolytic Drugs from Herbal Medicine

Anxiety is a widespread psychiatric disorder. The search for a cure is still continuing since many of the synthetic drugs were inefficient in completely treating anxiety, yet caused some dangerous side effects until many of the drugs were withdrawn from the market. One promising source of new anxiolytics could be herbal medicines. The challenge is to screen plant extracts. Rodent models can be used for this purpose but are expensive. Moreover, rodent tests are costly and consume relatively large quantities of sample. For this reason, alternative animal models may be useful. Zebrafish larvae have many advantages for screening natural products. The main advantage is that they can be produced cheaply and in large numbers. Several studies have shown that the zebrafish is a good model for studying drugs that affect anxiety. This review focuses on the use of animal models, including zebrafish larvae, for studying anxiety and screening for herbal medicines that modulate anxiety. Finally, future prospects of the zebrafish larva as an alternative model in this field are also discussed.

Excavating Anticonvulsant Compounds from Prescriptions of Traditional Chinese Medicine in the Treatment of Epilepsy

Traditional Chinese medicine (TCM) has a long history and been widely used in prevention and treatment of epilepsy in China. This paper is intended to review the advances in the active anticonvulsant compounds isolated from herbs in the prescription of TCM in the treatment of epilepsy. These compounds were introduced with the details including classification, CAS number specific structure and druggability data. Meanwhile, much of the research in these compounds in the last two decades has shown that they exhibited favorable pharmacological properties in treatment of epilepsy both in in vivo and in vitro models. In addition, in this present review, the evaluation of the effects of the anticonvulsant classical TCM prescriptions is discussed. According to these rewarding pharmacological effects and chemical substances, the prescription of TCM herbs could be an effective therapeutic strategy for epilepsy patients, and also could be a promising source for the development of new drugs.

Zebrafish-based identification of the antiseizure nucleoside inosine from the marine diatom Skeletonema marinoi

With the goal of identifying neuroactive secondary metabolites from microalgae, a microscale in vivo zebrafish bioassay for antiseizure activity was used to evaluate bioactivities of the diatom Skeletonema marinoi, which was recently revealed as being a promising source of drug-like small molecules. A freeze-dried culture of S. marinoi was extracted by solvents with increasing polarities (hexane, dichloromethane, methanol and water) and these extracts were screened for anticonvulsant activity using a larval zebrafish epilepsy model with seizures induced by the GABAA antagonist pentylenetetrazole. The methanolic extract of S. marinoi exhibited significant anticonvulsant activity and was chosen for bioassay-guided fractionation, which associated the bioactivity with minor constituents. The key anticonvulsant constituent was identified as the nucleoside inosine, a well-known adenosine receptor agonist with previously reported antiseizure activities in mice and rat epilepsy models, but not reported to date as a bioactive constituent of microalgae. In addition, a UHPLC-HRMS metabolite profiling was used for dereplication of the other constituents of S. marinoi. Structures of the isolated compounds were elucidated by nuclear magnetic resonance and high-resolution spectrometry. These results highlight the potential of zebrafish-based screening and bioassay-guided fractionation to identify neuroactive marine natural products.

The effects of herbal medicine on epilepsy

Traditional herbal medicine plays a significant role in the treatment of epilepsy. Though herbal medicine is widely used in antiepileptic treatment, there is a lack of robust evidence for efficacy and toxicity of most herbs. Besides, the herbal medicine should be subject to evidence-based scrutiny. In this context, we present a review to introduce the effects of herbal medicine on epilepsy. However, hundreds of herbal medicines have been investigated in the available studies. Some commonly used herbal medicines for epilepsy have been listed in our study. The overwhelming majority of these data are based on animal experiments. The lack of clinical data places constraints on the clinical recommendation of herbal medicine. Our study may conduct further studies and provide some insight on the development of anti-epileptic drugs.

Pharmacognostical Sources of Popular Medicine To Treat Alzheimer's Disease

BACKGROUND

A large number of classical and recently discovered plants are indicated in preventing and/or treating Alzheimer's disease (AD).

OBJECTIVE

Name of plants with their anti-AD effects are important for their further use and investigation.

METHOD

A short overview of AD is given; anti-Alzheimer plants are given in a Table.

RESULTS

Various medicinal plants are listed here as sources of popular medicines to be used in cases when patients are afraid of developing and/or suffer from AD. Some of these plants have been used for centuries. The major sources in the literature, over one hundred of references are given for plants that show beneficial effect on the progress of AD.

CONCLUSION

Plant extracts are widely used addition to the synthetic drugs approved by various administrative authorities to stop/slow down the progress of symptoms of AD.