Cytotoxicity and Toxicity Evaluation of Xanthone Crude Extract on Hypoxic Human Hepatocellular Carcinoma and Zebrafish (Danio rerio) Embryos

Acute toxicity of deoxynivalenol and bioremediation of a highly effective deoxynivalenol degrading Achromobacter spanius P-9 on zebrafish embryos and adults

Deoxynivalenol (DON) is one of the mostly concerned mycotoxins and several microbes showed bioremediation effects on DON toxic effects. In this study, the acute toxicity of a new DON degrading strain Achromobacter spanius P-9 with DON on zebrafish embryos and adults were firstly performed. For zebrafish embryos, bacterial concentrations of 2.5 × 107 CFU/mL and 5.0 × 107 CFU/mL had no significant effects on growth and development. However, at 7.5 × 107 CFU/mL, some effects were observed, and at 10.0 × 107 CFU/mL, the embryo survival rate decreased to 70%, with 3.3% teratogenicity. Higher bacterial concentrations correlated with faster heart rates. DON (100 μg/mL) significantly reduced embryo survival to 36.7% in 96 h. Bacterial solutions at 7.5 × 107 CFU/mL and 10.0 × 107 CFU/mL expanded the zebrafish intestinal tissue wall, while DON at 100 μg/mL negatively impacted intestinal morphology. Liver tissue in zebrafish exposed to Achromobacter spanius P-9 showed no significant differences from the control group. However, exposure to DON solution increased liver fluorescence intensity and caused liver cell changes, including edema, vacuolization, and blurred boundaries. For adult zebrafish, the ROS and 8-OHdG contents in the exposure group increased with the increase of bacterial solution concentration, the SOD enzyme activity, CAT enzyme activity, GST enzyme activity and MDA was not significantly different with the control group. Compared with the control group, the content of ROS, GST enzyme activity, MDA and 8-OHdG after DON treatment showed an upward trend, SOD and CAT enzyme activities showed a decreasing trend. Achromobacter spanius P-9 has no obvious inhibitory effect on the growth and development of zebrafish embryos and has no obvious death and toxicity during the growth of adult fish, providing data support for the future application of this strain in the biodegradation of DON.

Reviewing the use of zebrafish for the detection of neurotoxicity induced by chemical mixtures through the analysis of behaviour

The knowledge and assessment of mixtures of chemical pollutants in the aquatic environment is a complex issue that is often challenging to address. In this review, we focused on the use of zebrafish (Danio rerio), a vertebrate widely used in biomedical research, as a model for detecting the effects of chemical mixtures with a focus on behaviour. Our aim was to summarize the current status of the ecotoxicological research in this sector. Specifically, we limited our research to the period between January 2012 and September 2023, including only those works aimed at detecting neurotoxicity through behavioural endpoints, utilizing zebrafish at one or more developmental stages, from egg to adult. Additionally, we gathered the findings for every group of chemicals involved and summarised data from all the works we included. At the end of the screening process 101 papers were considered eligible for inclusion. Results show a growing interest in zebrafish at all life stages for this kind of research in the last decade. Also, a wide variety of different assays, involving different senses, was used in the works we surveyed, with exposures ranging from acute to chronic. In conclusion, the results of this study show the versatility of zebrafish as a model for the detection of mixture toxicity although, for what concerns behavioural analysis, the lack of standardisation of methods and endpoints might still be limiting.

Inhibition of Seizure-Like Paroxysms and Toxicity Effects of Securidaca longepedunculata Extracts and Constituents in Zebrafish Danio rerio

Plants used in traditional medicine in the management of epilepsy could potentially yield novel drug compounds with antiepileptic properties. The medicinal plant Securidaca longepedunculata is widely used in traditional medicine in the African continent, and epilepsy is among several indications. Limited knowledge is available on its toxicity and medicinal effects, such as anticonvulsant activities. This study explores the potential in vivo inhibition of seizure-like paroxysms and toxicity effects of dichloromethane (DCM) and ethanol (EtOH) extracts, as well as isolated xanthones and benzoates of S. longepedunculata. Ten phenolic compounds were isolated from the DCM extract. All of the substances were identified by nuclear magnetic resonance spectroscopy. Assays for toxicity and inhibition of pentylenetetrazole (PTZ)-induced seizure-like paroxysms were performed in zebrafish larvae. Among the compounds assessed in the assay for maximum tolerated concentration (MTC), benzyl-2-hydroxy-6-methoxy-benzoate (MTC 12.5 μM), 4,8-dihydroxy-1,2,3,5,6-pentamethoxyxanthone (MTC 25 μM), and 1,7-dihydroxy-4-methoxyxanthone (MTC 6.25 μM) were the most toxic. The DCM extract, 1,7-dihydroxy-4-methoxyxanthone and 2-hydroxy-1,7-dimethoxyxanthone displayed the most significant inhibition of paroxysms by altering the locomotor behavior in GABAA receptor antagonist, PTZ, which induced seizures in larval zebrafish. The EtOH extract, benzyl benzoate, and benzyl-2-hydroxy-6-methoxy-benzoate unexpectedly increased locomotor activity in treated larval zebrafish and decreased locomotor activity in nontreated larval zebrafish, seemingly due to paradoxical excitation. The results reveal promising medicinal activities of this plant, contributing to our understanding of its use as an antiepileptic drug. It also shows us the presence of potentially new lead compounds for future drug development.

Mutated Shiitake extracts inhibit melanin-producing neural crest-derived cells in zebrafish embryo

The ability of natural extracts to inhibit melanocyte activity is of great interest to researchers. This study evaluates and explores the ability of mutated Shiitake (A37) and wildtype Shiitake (WE) extract to inhibit this activity. Several properties such as total phenolic (TPC) and total flavonoid content (TFC), antioxidant activity, effect on cell and component profiling were conducted. While having no significant differences in total phenolic content, mutation resulted in A37 having a TFC content (1.04 ± 0.7 mg/100 ml) compared to WE (0.86 ± 0.9 mg/100 ml). Despite that, A37 extract has lower antioxidant activity (EC50, A37 = 549.6 ± 2.70 μg/ml) than WE (EC50 = 52.8 ± 1.19 μg/ml). Toxicity tests on zebrafish embryos show that both extracts, stop the embryogenesis process when the concentration used exceeds 900 μg/ml. Although both extracts showed pigmentation reduction in zebrafish embryos, A37 extract showed no effect on embryo heartbeat. Cell cycle studies revealed that WE significantly affect the cell cycle while A37 not. Further tests found that these extracts inhibit the phosphorylation of Glycogen synthase kinase 3 β (pGSK3β) in HS27 cell line, which may explain the activation of apoptosis in melanin-producing cells. It was found that from 19 known compounds, 14 compounds were present in both WE and A37 extracts. Interestingly, the presence of decitabine in A37 extract makes it very potential for use in the medical application such as treatment of melanoma, skin therapy and even cancer.

Zebrafish as a Successful Animal Model for Screening Toxicity of Medicinal Plants

The zebrafish (Danio rerio) is used as an embryonic and larval model to perform in vitro experiments and developmental toxicity studies. Zebrafish may be used to determine the toxicity of samples in early screening assays, often in a high-throughput manner. The zebrafish embryotoxicity model is at the leading edge of toxicology research due to the short time required for analyses, transparency of embryos, short life cycle, high fertility, and genetic data similarity. Zebrafish toxicity studies range from assessing the toxicity of bioactive compounds or crude extracts from plants to determining the optimal process. Most of the studied extracts were polar, such as ethanol, methanol, and aqueous solutions, which were used to detect the toxicity and bioactivity. This review examines the latest research using zebrafish as a study model and highlights its power as a tool for detecting toxicity of medicinal plants and its effectiveness at enhancing the understanding of new drug generation. The goal of this review was to develop a link to ethnopharmacological zebrafish studies that can be used by other researchers to conduct future research.