Neuroprotective effect of Kojic acid in Rotenone - induced Parkinsonism in a Zebrafish Model

Potent anti-melanogenic activity and favorable toxicity profile of selected 4-phenyl hydroxycoumarins in the zebrafish model and the computational molecular modeling studies

Melanin overproduction causes various skin diseases, such as spots, freckles, and wrinkles, resulting in the requirement of melanin synthesis inhibitors like 1-phenyl-2-thiourea (PTU) and kojic acid, which have been commonly used in the pharmaceutical industry. However, these inhibitors can cause side effects such as skin irritation and allergies. Therefore, it is necessary to develop safe and effective melanin inhibitors from natural resources. The purpose of this study was to investigate a whitening agent from natural substances using B16F10 melanoma cells and zebrafish model. We investigated the melanogenesis-inhibiting activities of the fractions from Sargassum pallidum extract. The ethyl acetate fraction from S. pallidum extract (SPEF) significantly decreased tyrosinase activity. SPEF also significantly reduced α-melanocyte stimulating hormone (MSH)-induced intracellular tyrosinase activity and melanin content in B16F10 cells. Moreover, SPEF inhibited the expression levels of key melanogenic proteins such as tyrosinase, TRP-1, TRP-2, and MITF by downregulating the phosphorylation levels of CREB and PKA in α-MSH-stimulated melanoma cells. Furthermore, SPEF significantly suppressed melanin synthesis in the zebrafish model with no developmental toxicity. LC-Q-TOF-MS/MS analysis identified that SPEF was composed of 12 phytochemical compounds, including diterpenes, which were the dominant metabolites. These results altogether show that SPEF effectively suppresses melanogenesis in B16F10 melanoma cells and in a zebrafish model, with potential for usage in pharmaceuticals and cosmeceuticals.

Neuroprotective effects of Shenghui decoction via inhibition of the JNK/p38 MAPK signaling pathway in an AlCl3-induced zebrafish (Danio rerio) model of Alzheimer's disease

Neuroprotective effect of nano-carboxymethyl chitosan from Doryteuthis sibogae against rotenone-induced Parkinson's disease in the zebrafish model.

Neuroprotective effects of nanogold-based Ayurveda medicine Suvarna Bhasma against rotenone-induced Parkinson's-like model

Epilepsy is one of the most common neurological disorders, and it is characterized by spontaneous seizures. In a previous study, we identified 4-(2-chloro-4-fluorobenzyl)-3-(2-thienyl)-1,2,4-oxadiazol-5(4H)-one (GM-90432) as a novel anti-epileptic agent in chemically- or genetically-induced epileptic zebrafish and mouse models. In this study, we investigated the anti-epileptic effects of GM-90432 through neurochemical profiling-based approach to understand the neuroprotective mechanism in a pentylenetetrazole (PTZ)-induced epileptic seizure zebrafish model. GM-90432 effectively improved PTZ-induced epileptic behaviors via upregulation of 5-hydroxytryptamine, 17-β-estradiol, dihydrotestosterone, progesterone, 5α -dihydroprogesterone, and allopregnanolone levels, and downregulation of normetanephrine, gamma-aminobutyric acid, and cortisol levels in brain tissue. GM-90432 also had a protective effect against PTZ-induced oxidative stress and zebrafish death, suggesting that it exhibits biphasic neuroprotective effects via scavenging of reactive oxygen species and anti-epileptic activities in a zebrafish model. In conclusion, our results suggest that neurochemical profiling study could be used to better understand of anti-epileptic mechanism of GM-90432, potentially leading to new drug discovery and development of anti-seizure agents.

Disruption of the gut-brain axis in Parkinson's disease (PD) may lead to motor symptoms and PD pathogenesis. Recently, the neuroprotective potential of different PPARδ-agonists has been shown. We aimed to reveal the effects of erucic acid, peroxisome proliferator-activated receptors (PPARs)-ligand in rotenone-induced PD model in zebrafish, focusing on the gut-brain axis. Adult zebrafish were exposed to rotenone and erucic acid for 30 days. Liquid chromatography-mass spectrometry and tandem mass spectrometry (LC-MS/MS) analysis was performed. Raw files were analysed by Proteome Discoverer 2.4 software; peptide lists were searched against Danio rerio proteins. STRING database was used for protein annotations or interactions. Lipid peroxidation (LPO), nitric oxide (No), alkaline phosphatase, superoxide dismutase, glutathione S-transferase (GST), acetylcholinesterase and the expressions of PD-related genes were determined. Immunohistochemical tyrosine hydroxylase (TH) staining was performed. LC-MS/MS analyses allowed identification of over 2000 proteins in each sample. The 2502 and 2707 proteins overlapped for intestine and brain. The 196 and 243 significantly dysregulated proteins in the brain and intestines were found in rotenone groups. Erucic acid treatment corrected the changes in the expression of proteins associated with cytoskeletal organisation, transport and localisation and improved locomotor activity, expressions of TH, PD-related genes (lrrk2, park2, park7, pink1) and oxidant-damage in brain and intestines in the rotenone group as evidenced by decreased LPO, No and increased GST. Our results showed beneficial effects of erucic acid as a PPARδ-ligand in neurotoxin-induced PD model in zebrafish. We believe that our study will shed light on the mechanism of the effects of PPARδ agonists and ω9-fatty acids in the gut-brain axis of PD.

Sodium-dependent glucose co-transporter-2 inhibitor empagliflozin exerts neuroprotective effects in rotenone-induced Parkinson’s disease model in zebrafish; mechanism involving ketogenesis and autophagy

Retinitis pigmentosa (RP) and associated inherited retinal diseases (IRDs) are caused by rod photoreceptor degeneration, necessitating therapeutics promoting rod photoreceptor survival. To address this, we tested compounds for neuroprotective effects in multiple zebrafish and mouse RP models, reasoning drugs effective across species and/or independent of disease mutation may translate better clinically. We first performed a large-scale phenotypic drug screen for compounds promoting rod cell survival in a larval zebrafish model of inducible RP. We tested 2934 compounds, mostly human-approved drugs, across six concentrations, resulting in 113 compounds being identified as hits. Secondary tests of 42 high-priority hits confirmed eleven lead candidates. Leads were then evaluated in a series of mouse RP models in an effort to identify compounds effective across species and RP models, that is, potential pan-disease therapeutics. Nine of 11 leads exhibited neuroprotective effects in mouse primary photoreceptor cultures, and three promoted photoreceptor survival in mouse rd1 retinal explants. Both shared and complementary mechanisms of action were implicated across leads. Shared target tests implicated parp1-dependent cell death in our zebrafish RP model. Complementation tests revealed enhanced and additive/synergistic neuroprotective effects of paired drug combinations in mouse photoreceptor cultures and zebrafish, respectively. These results highlight the value of cross-species/multi-model phenotypic drug discovery and suggest combinatorial drug therapies may provide enhanced therapeutic benefits for RP patients.

Fascaplysin is a bioactive compound derived from marine sponges, which have anticancer properties and potential neuroprotective effects mediated by mitigation of oxidative stress-induced neurotoxicity. This study investigated the concentration-dependent effects of fascaplysin in zebrafish models, focusing on embryonic survival, cardiac function, melanocyte formation, and peripheral nerve health. Zebrafish embryos were exposed to fascaplysin at concentrations ranging from 10 nM to 100 μM, and developmental parameters were assessed. At higher concentrations (≥1 μM), fascaplysin significantly decreased embryo survival rates, delayed hatching, impaired cardiac function, and caused morphological abnormalities, including disruption of melanocyte formation and structural deformities. By contrast, lower concentrations (10 nM and 100 nM) did not exhibit significant toxicity. In adult zebrafish, fascaplysin at 100 nM reduced the expression of superoxide-producing enzymes and preserved peripheral nerve integrity following injury, as demonstrated by maintenance of fluorescence in transgenic zebrafish with expression of green fluorescent protein in Schwann cells. These findings suggest that fascaplysin exhibits peripheral neuroprotective effects at low concentrations, potentially through the reduction of oxidative stress and preservation of Schwann cell function. However, the toxicity observed at higher concentrations highlights the importance of dose optimization. Fascaplysin is a promising candidate for the development of new therapeutic strategies for peripheral neuropathies, and further studies are required to elucidate the underlying mechanisms and validate its efficacy in mammalian models.

While rapamycin was discovered as a fungicide in 1975, it is now famous for its ability to suppresses mammalian cell aging1,2 and to extend lifespan in mice.3,4 Rapamycin is an oral immunomodulatory agent approved to prevent rejection in human organ transplantation. It also exerts an antitumor activity as well as an anti-restenosis activity, when used in drug-eluting stents. In addition, rapamycin has neuroprotective effects in traumatic brain injury models, with increased neuron survival and recovery of brain functions. Nevertheless, there has been a practical limitation in performing physiologic studies with rapamycin, because rapamycin has very poor water solubility and bioavailability.5 To maximize the research and clinical application of rapamycin, it is advantageous to dissolve rapamycin in a physiologic and isotonic solution. To overcome this limitation (poor water solubility), we solubilized rapamycin in isotonic buffer using reconstituted high-density lipoprotein containing V156K-apoA-I (V156K-rHDL).6 Apolipoprotein (apo) A-I is a principal protein component of HDL and is known to perform a beneficial role in the reverse cholesterol transport pathway through its antioxidant and antiinflammatory activities. HDL have atheroprotective effects with potent antioxidant, antiinflammatory, anti-diabetic activities. Recently, we showed that rHDL containing V156K-apoA-I, had a potent antioxidant activity and was more resistant to glycation, with more enhanced tissue regeneration activity as a HDL-therapy. More resistance to glycation is advantageous to develop a protein-based drug for both anti-atherosclerotic and anti-diabetic agents. These results suggest that V156K-rHDL could be applied to facilitate facultative regeneration in aging-related complications.7 There has been several nanobiotechnology applications of rHDL to encapsulate doxorubicin, amphotericin and adenovirus. Our research group recently reported that the efficiency of viral gene delivery and the stability of the adenovirus (Ad) were significantly enhanced when Ad is incorporated with rHDL containing WT- or V156K-apoA-I in cellular and zebrafish models.8 The report raised the feasibility that rHDL can be used as a formulated vehicle for viral and gene/drug delivery. We showed a new method to solubilize rapamycin for better delivery across several barriers, such as blood-brain barrier and skin barrier. Rapamycin (final 0.1 mg/mL) was solubilized in rHDL containing either wild-type (WT) or V156K (1 mg/mL of protein). V156K-rHDL containing rapamycin (V156K-rapa-rHDL) had a slightly larger particle size than WT-rHDL containing rapamycin (WT-rapa-rHDL). V156K-rapa-rHDL had enhanced antioxidant ability and anti-atherosclerotic activity. Treatment of V156K-rapa-rHDL resulted in attenuated senescence in human cells, with increased cell survival compared with WT-rapa-rHDL or rHDL alone, indicating that V156K-rapa-rHDL has various applications for suppression of cellular senescence and tissue regeneration activities in the zebrafish model. Incorporation of rapamycin into rHDL containing apoA-I, especially its V156K variant, can promote cell survival and suppress senescence through enhanced antioxidant ability. V156K-apoA-I has been developed by site-directed mutagenesis by our research group and has been shown to have more potent antioxidant and anti-inflammatory activities in vivo and in vitro, as well as an in vivo anti-atherosclerotic effect. In conclusion, the enhanced solubility of rapamycin in rHDL particles may be applicable to the development of numerous types of therapeutics. Because cardiovascular disease and type 2 diabetes are age-related diseases, chronic metabolic disease progression with senescence may be linked to target of rapamycin (TOR) signaling. Rapamycin and rHDL possess independent therapeutic activities, and the beneficial activities of rHDL were not impaired by incorporation of rapamycin. New agents can likely be developed from rapa-rHDL to treat aging, cardiovascular and brain disease, as HDL can penetrate the blood-brain barrier. These same protocols can be applied to solubilize other hydrophobic drugs for a wide range of therapeutic applications.

WITHDRAWN: Revealing the neuroprotection and neurodegeneration efficacy of marine sponge extract in Parkinson's disease using gene expression and molecular docking

Flavonoids have been reported to be potent antioxidants and beneficial in the treatment of oxidative stress-related diseases. Quercetin, a major flavonoid naturally occurring in plants, deserves attention because of its beneficial effects observed in various in vitro and in vivo neural damage models; however, the actions of quercetin are paradoxical. In an effort to confirm the neuroprotective effect of quercetin and to elucidate its mechanism of action, the neuroprotective effects of quercetin in PC12 cells and in zebrafish models were investigated. In this study, the selective dopaminergic neurotoxin 6-hydroxydopamine (6-OHDA), was used to induce neural damage in PC12 cells and zebrafish models. Pretreatment with quercetin offered neuroprotection against 6-OHDA-induced PC12 cell death. Moreover, quercetin could prevent 6-OHDA-induced PC12 cell apoptosis and 6-OHDA-stimulated dopaminergic neuron loss in zebrafish. Interestingly, quercetin was able to protect, but not rescue the dopaminergic neuron damage when zebrafish were treated with quercetin at different maturation stages of the blood brain barrier. A mechanistic study showed that quercetin could inhibit NO over-production and iNOS over-expression in PC12 cells and could down-regulate the over-expression of pro-inflammatory genes (e.g. IL-1ß, TNF-α and COX-2) in zebrafish, suggesting that these genes play a role in the neuroprotective effect of quercetin. The objective of this study was to provide a scientific rationale for the clinical use of quercetin, leading to its development as an effective therapeutic agent for the treatment of Parkinson's disease.

Background Parkinson's disease (PD) is a debilitating neurodegenerative disorder characterized by the progressive loss of dopaminergic neurons. This study explores the neuroprotective effects of Kapikachhu (Mucuna pruriens) in a paraquat (PQ)-induced zebrafish model of neurotoxicity relevant to PD. Utilizing a zebrafish model exposed to PQ to induce parkinsonian-like symptoms and assess the potential therapeutic benefits of Kapikachhu seed extract. The extract (20 mg/kg) was administered intraperitoneally, and behavioural, histological, and dopamine analyses were performed. Behavioural assessments revealed that Kapikachhu-treated zebrafish exhibited a 30% improvement in mean swimming speed and a 40% increase in dopamine levels compared to PQ-exposed zebrafish. These results suggest that Kapikachhu mitigates PQ-induced neurotoxicity through its neuroprotective properties. Objective and methods This study investigates the neuroprotective effects of Kapikachhu in a PQ-induced zebrafish model of neurotoxicity relevant to PD. A zebrafish model was exposed to PQ to induce parkinsonian-like symptoms, and the therapeutic potential of Kapikachhu seed extract was evaluated. The extract was administered to zebrafish, and behavioural, histological and dopamine analyses were performed. Behavioural assessments, including novel tank, light–dark, and mirror-induced aggression tests, demonstrated that Kapikachhu-treated zebrafish exhibited reduced anxiety-like behaviours and improved motor function compared to untreated PQ-exposed zebrafish. Results Histopathological analysis revealed reduced Lewy bodies and milder morphological changes in kapikachhu-treated groups, indicating its potential to protect against PQ-induced neurodegeneration. HPLC analysis supported these findings, showing that kapikachhu helps restore key brain metabolites depleted by PQ. Conclusion These results suggest that kapikachhu has notable neuroprotective effects in a zebrafish model of PD, potentially due to its antioxidant properties and ability to mitigate oxidative stress. This study supports the therapeutic potential of kapikachhu for neuroprotection and warrants further investigation into its mechanisms of action and efficacy in more complex models of PD. This is the first study to explore the combination of kapikachhu, paraquat, and adult zebrafish. Graphical Abstract The image outlines an experimental process investigating the neuroprotective effects of kapikachhu extract on paraquat-induced neurotoxicity in zebrafish. It begins with the preparation of kapikachhu seeds, followed by methanolic extraction and analysis of L-Dopa content using HPLC. Zebrafish are then anesthetized and injected with various treatments, including paraquat and kapikachhu extract, to study their effects on motor behaviour. The fish are observed for behavioral changes, and their brains are dissected for dopamine quantification and histopathological analysis. This study aims to validate Kapikachhu's potential in mitigating neurotoxic damage caused by paraquat.

Eisenia bicyclis (Kjellman) Setchell is an edible perennial brown alga in the family Lessoniaceae and is widely distributed in the coastal area of Ulleung and Jeju islands in Korea, and in Japan [1, 2]. Previous studies on E. bicyclis, have investigated several biological activities including anti-inflammation, antioxidative, and neuroprotective effects. In continuation of our search for anti-diabetic compound from natural products, we have found that the EtOH extract of E. bicyclis has antihyperglycemic activity in the zebrafish model for type 1 and 2 diabetes. Type 1 diabetes zebrafish model was induced by alloxan, which cause pancreatic β-cell necrosis [3]. In addition, type 2 diabetes zebrafish model was induced by insulin. Exposure to excess insulin can induce insulin resistance typical of type 2 diabetes [4]. Following alloxan or insulin treatment, pancreatic islet size and fluorescence intensity were measured. The EtOH extract was consecutively partitioned with CH2Cl2, EtOAc and n-BuOH to give four fractions. Among these fractions, the EtOAc fraction which showed antihyperglycemic activity was subjected to activity-guided fractionation and isolation. Three phlorotannins, eckol, dieckol and phlorofucofuroeckol-A, were isolated from the EtOAc fraction. The isolated compounds revealed anti-diabetic activity for type1 and 2 in the zebrafish model.