Toxicity Assessment of Herbal Medicine Using Zebrafish Embryos: A Systematic Review

Developmental and organ toxicity of fenpropimorph in zebrafish: Involvement of apoptosis and inflammation

Pesticides are increasingly the focus as a prominent factor in environmental pollution. Fenpropimorph, a widely utilized morpholine fungicide, is a significant water pollutant. Because of its extensive usage, fenpropimorph is readily detected in diverse aquatic ecosystems. Despite its well-known toxicity to aquatic organisms, its toxicity to zebrafish development and accompanying mechanics remain unexplored. To assess fenpropimorph's toxicity and potential mechanism, we employed the zebrafish model, a representative tool in toxicological studies. Our results showed that exposure to fenpropimorph reduced embryonic viability during the early stages of development and reduced head and body size. Moreover, fenpropimorph triggered apoptosis, DNA fragmentation, and inflammation. Aberrations in the vascular network were observed in the fli1:eGFP transgenic zebrafish model. Additionally, neurotoxic impacts were further assessed using transgenic olig2:dsRed zebrafish, accompanied by a reduction of liver size and fluorescence intensity of fabp10a:dsRed zebrafish. mRNA expression analysis related to corresponding organ development further supported our data. Overall, our research suggests that fenpropimorph may cause aberrations in aquatic organisms.

Leaf and fruit extracts of Solanum betaceum Cav.: Antioxidant potential and embryotoxicity using a zebrafish model

This study aimed to evaluate the antioxidant potential and toxicological effects of Solanum betaceum leaf and fruit extracts on zebrafish embryos. Leaf and fruit pulp extracts were prepared by turbo extraction using distilled water or methanol as solvent. The levels of total phenols and flavonoids were quantified. The antioxidant potential was assessed by the total antioxidant capacity test and two free radical scavenging tests. The toxic effects of S. betaceum species were assessed using an acute toxicity test on zebrafish embryos exposed to S. betaceum extracts. The leaves of S. betaceum were found to have high total phenolic and flavonoid content, high total antioxidant capacity and high toxicity to developing zebrafish embryos, with a teratogenic index (TI) equal to 17.65. The leaves are used topically in folk medicine, which may allow for safer utilization of phenolics compared to oral ingestion. The fruits had higher free radical scavenging activity and lower toxicity for the embryos than the leaves, with the TI around 2.2. Water was a more suitable solvent than methanol for obtaining safer bioactive compounds from S. betaceum leaf and fruit. This work provides an initial basis for pharmacological studies of S. betaceum species in animal models.

Phytoceutical isoquercitrin and ethanolic extracts from pequi (Caryocar coriaceum Wittm) reverse alcohol withdrawal-induced anxiety in adult zebrafish (Danio rerio)

Pharmacotherapy in Alcohol Withdrawal Syndrome (AWS), which is a mental disorder, generally involves benzodiazepines due to their action via GABA, but their side effects, such as excessive sedation, mental confusion and risk of dependence, are considerable. It is important to investigate the anxiolytic potential of plants such as Caryocar coriaceum, due to the presence of secondary metabolic compounds, such as isoquercitrin, capable of promoting the reduction of anxiety during AWS. We evaluated the anxiolytic-like potential of ethanolic extracts from the leaves (EEPL) and pulp (EEPP) of C. coriaceum, and its major compound, isoquercitrin (IsoQuer), in adult zebrafish (Danio rerio) during alcohol withdrawal. Adult zebrafish (n = 8 per group) were treated (20 µL; p.o) with EEPL, or EEPP or IsoQuer (0.01 or 0.05 or 0.1 or 0.5 or 1.0 mg/mL) and submitted to the 96-hour acute toxicity test. Flumazenil in adult zebrafish and molecular Docking of IsoQuer were used to investigate the GABAergic involvement. Finally, the anxiolytic-like activity was evaluated during alcohol withdrawal in adult zebrafish. The results indicated that EEPL, EEPP and IsoQuer are safe and have no sedative effect on adult zebrafish. Furthermore, they demonstrated a pharmacological potential in the treatment of alcohol withdrawal-induced anxiety, mediated by the GABAergic system, evidenced in the in-silico study by the stable isoquercitrin-GABAA complex, the main constituent of the extracts. These findings suggest an anxiolytic herbal potential of C. coriaceum and isoquercitrin, providing an alternative for the treatment of anxiety associated with AWS.

Spatial metabolomics revealed multi-organ toxicity and visualize metabolite changes induced by borneol in zebrafish

This study focuses on the potential hazards of borneol (BO) to aquatic organisms and human health. BO has antibacterial, anti-inflammatory and antioxidant activities, and is widely used in medicine, cosmetics, and detergents. In this study, zebrafish was used as a model organism to systematically evaluate the effects of BO on the heart, liver, kidney, and nervous system. The effects of BO on metabolites of zebrafish were studied using MALDI-MSI. The results showed that a high concentration of BO (500 μM) could induce morphological abnormalities (swim-bladder loss, spinal curvature, body-length shortening), cardiotoxicity (decreased heart rate, increased SV-BA distance), hepatotoxicity (reduced liver area index), and neurotoxicity (impaired behavioral ability, and dopamine neuron development deficits), but there was no renal toxicity observed in zebrafish. Additionally, MALDI-MSI analysis showed that BO exposure significantly altered the levels of metabolites, including phospholipids, fatty acids, choline, and amino acids. The contents of PC-34:1, PC-34:2, PI-36:4, PE-36:1, LysoPE-22:5, LysoPC-18:1, FA-18:2, phenylalanine, lysine and glutathione were significantly increased, while the contents of PC-38:6 and PC-40:6 were significantly decreased. Notably, BO elicited a significant alteration in the mRNA expression levels of genes associated with phospholipid metabolism, fatty acid metabolism, choline metabolism, and amino acid metabolism (such as elovl5, chpt1, chka, setd7, hgd). This study revealed that BO exerted toxicity on multiple organs and demonstrated that BO causes metabolic dysregulation in zebrafish. These findings provide a novel insight into the toxicity of BO.

Tranquilizing and hepatoprotective effects of red-eye tetra (Moenkhausia Forestii) diet fed with Erythrina crista-galli

This study aimed to assess the leaf aqueous extract composition of Erythrina crista-galli and the effects of its inclusion on the diet of red-eye tetra (Moenkhausia forestii), concerning enzyme content of digestive, hepatic, and oxidation metabolism and pigmentation. Fish (1.78 ± 0.54 g) were divided into groups: fasting (without feeding), control (commercial feed), and treatment (commercial feed with leaf aqueous extract of E. crista-galli) and feeding apparent satiety for 21 days, in the extracted analysis by mass spectrometry, phenolic compost, and flavonoids. The agitation degree and number of dashes, in all supplemented treatments, were lower than those in the control diet when fed for 7 or 15 days. In the digestive enzymatic activity did not differ (p > 0.05). The hepatoprotective treatment group showed lower alanine aminotransferase (ALT) and higher levels of antioxidant catalase (CAT). The results indicated that the aqueous leaf extract of Erythrina crista-galli assists in function maintenance of the liver; and stimulates CAT in red-eye tetra, suggesting that the identified compounds act on the liver and skin, showing hepatoprotective effects and stimulating tranquility.

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.

Toxicological and Sedative Effects of Chipilin (Crotalaria longirostrata) Leaf Extracts Obtained by Maceration and Supercritical Fluid Extraction

Chipilin (Crotalaria longirostrata) is consumed as a vegetable in the preparation of traditional dishes. As a folk medicine, Chipilin extracts are used as a hypnotic and sedative agent; however, there are few reports that support these uses. This study aimed to characterize the compounds present in Chipilin leaf extracts and to investigate their sedative effect using zebrafish as an in vivo model. Extracts were obtained by maceration with water (H2O), ethanol (EtOH), and EtOH-H2O, while oleoresin was obtained by supercritical fluid extraction (SFE). Total phenolic and flavonoid contents were quantified by colorimetric methods. Phytochemical constituents were identified by gas chromatography-mass spectrometry (GC-MS) analysis. The chronic and acute toxicities of Chipilin extracts were tested in zebrafish embryos and larvae, respectively. Chipilin sedative effect was tested by the larvae response to dark-light-dark transitions. EtOH-H2O extracts had the highest value of total phenolics (5345 ± 5.1 μg GAE/g), followed by water and oleoresin (1815 ± 5.1 and 394 ± 5.1 μg GAE/g, respectively). In water extracts were identified the alkaloid trachelanthamidine, 1,2β-epoxy- and the alkyl ketone 7,9-di-tert-butyl-1-oxaspiro(4,5)deca-6,9-diene-2,8-dione, while oleamide, α-monostearin, and erucamide were detected in all samples except in water extracts. Oleoresin extract had the lowest embryotoxicity (LC50 = 4.99 μg/mL) and the highest sedative effects. SFE is a green alternative to obtain Chipilin extracts rich in erucamide, an endocannabinoid analogue, which plays an important role in the development of the central nervous system and in modulating neurotransmitter release.

Evaluation of the Anti-Inflammatory and Antioxidant Potential of Cymbopogon citratus Essential Oil in Zebrafish

This study explored the protective capacity of the essential oil (EO) of Cymbopogon citratus against oxidative stress induced by hydrogen peroxide (H2O2) and the inflammatory potential in zebrafish. Using five concentrations of EO (0.39, 0.78, 1.56, 3.12, and 6.25 μg/mL) in the presence of 7.5 mM H2O2, we analyzed the effects on neutrophil migration, caudal fin regeneration, cellular apoptosis, production of reactive oxygen species (ROS), and activities of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and glutathione S-transferase (GST) after 96 h of exposure. A significant decrease in neutrophil migration was observed in all EO treatments compared to the control. Higher concentrations of EO (3.12 and 6.25 μg/mL) resulted in a significant decrease in caudal fin regeneration compared to the control. SOD activity was reduced at all EO concentrations, CAT activity significantly decreased at 3.12 μg/mL, and GST activity increased at 0.78 μg/mL and 1.56 μg/mL, compared to the control group. No significant changes in ROS production were detected. A reduction in cellular apoptosis was evident at all EO concentrations, suggesting that C. citratus EO exhibits anti-inflammatory properties, influences regenerative processes, and protects against oxidative stress and apoptosis.

Essential Oils Produce Developmental Toxicity in Zebrafish Embryos and Cause Behavior Changes in Zebrafish Larvae

Essential oils have gained significant popularity in various industries due to their biological properties, but their potential toxic effects on living organisms have been poorly investigated. This study aimed to evaluate the effects of lemongrass, thyme, and oregano essential oils on zebrafish embryos and larvae as animal models. Embryos were exposed to different concentrations of essential oils, and various endpoints were assessed, including epiboly, mortality (LC50), morphometry, and behavioral changes. All three essential oils reduced epiboly, affecting embryonic development. LC50 values were calculated for lemongrass (3.7 µg/mL), thyme (14.4 µg/mL), and oregano (5.3 µg/mL) oils. Larvae exposed to these oils displayed morphological defects, including growth reduction, spinal deformation, pericardial edema, eye size reduction, and reduced swim-bladder inflation. Morphometric analysis confirmed reduced larval length at higher oil concentrations. Essential-oil exposure altered zebrafish larval swimming behavior, with lemongrass oil reducing dark-cycle activity and oregano oil increasing light-cycle activity, suggesting neurodevelopmental toxicity. These findings illustrate the adverse effects of these oils on zebrafish embryos and larvae and reveal essential-oil toxicity, indicating careful use should be considered, particularly during pregnancy.

Phytochemical analysis, antioxidant, α-glucosidase inhibitory activity, and toxicity evaluation of Orthosiphon stamineus leaf extract

Ocimum aristatum, commonly known as O. stamineus, has been widely studied for its potential as an herbal medicine candidate. This research aims to compare the efficacy of water and 100% ethanolic extracts of O. stamineus as α-glucosidase inhibitors and antioxidants, as well as toxicity against zebrafish embryos. Based on the study findings, water extract of O. stamineus leaves exhibited superior inhibition activity against α-glucosidase, ABTS, and DPPH, with IC50 values of approximately 43.623 ± 0.039 µg/mL, 27.556 ± 0.125 µg/mL, and 95.047 ± 1.587 µg/mL, respectively. The major active compounds identified in the extract include fatty acid groups and their derivates such as linoleic acid, α-eleostearic acid, stearic acid, oleanolic acid, and corchorifatty acid F. Phenolic groups such as caffeic acid, rosmarinic acid, 3,4-Dihydroxybenzaldehyde, norfenefrine, caftaric acid, and 2-hydroxyphenylalanine and flavonoids and their derivates including 5,7-Dihydroxychromone, 5,7-Dihydroxy-2,6-dimethyl-4H-chromen-4-one, eupatorin, and others were also identified in the extract. Carboxylic acid groups and triterpenoids such as azelaic acid and asiatic acid were also present. This study found that the water extract of O. stamineus is non-toxic to zebrafish embryos and does not affect the development of zebrafish larvae at concentrations lower than 500 µg/mL. These findings highlight the potential of the water extract of O. stamineus as a valuable herbal medicine candidate, particularly for its potent α-glucosidase inhibition and antioxidant properties, and affirm its safety in zebrafish embryos at tested concentrations.

New Phocoenamicin and Maklamicin Analogues from Cultures of Three Marine-Derived Micromonospora Strains

Antimicrobial resistance can be considered a hidden global pandemic and research must be reinforced for the discovery of new antibiotics. The spirotetronate class of polyketides, with more than 100 bioactive compounds described to date, has recently grown with the discovery of phocoenamicins, compounds displaying different antibiotic activities. Three marine Micromonospora strains (CA-214671, CA-214658 and CA-218877), identified as phocoenamicins producers, were chosen to scale up their production and LC/HRMS analyses proved that EtOAc extracts from their culture broths produce several structurally related compounds not disclosed before. Herein, we report the production, isolation and structural elucidation of two new phocoenamicins, phocoenamicins D and E (1-2), along with the known phocoenamicin, phocoenamicins B and C (3-5), as well as maklamicin (7) and maklamicin B (6), the latter being reported for the first time as a natural product. All the isolated compounds were tested against various human pathogens and revealed diverse strong to negligible activity against methicillin-resistant Staphylococcus aureus, Mycobacterium tuberculosis H37Ra, Enterococcus faecium and Enterococcus faecalis. Their cell viability was also evaluated against the human liver adenocarcinoma cell line (Hep G2), demonstrating weak or no cytotoxicity. Lastly, the safety of the major compounds obtained, phocoenamicin (3), phocoenamicin B (4) and maklamicin (7), was tested against zebrafish eleuthero embryos and all of them displayed no toxicity up to a concentration of 25 μM.

A New Hypoglycemic Prenylated Indole Alkaloid N-Oxide from Endophytic Fungus Pallidocercospora crystalline

A new prenylated indole alkaloid-Penicimutamide C N-oxide (1), a new alkaloid penicimutamine A (2), along with six known alkaloids were isolated from an endophytic fungus Pallidocercospora crystallina. A simple and accurate method was used to determine the N-O bond in the N-oxide group of 1. By using a β-cell ablation diabetic zebrafish model, compounds 1, 3, 5, 6 and 8 showed significantly hypoglycemic activities under the concentration of 10 μM. Further studies revealed that compounds 1 and 8 lowered the glucose level through promoting glucose uptake in zebrafish. In addition, all eight compounds showed no acute toxicity, teratogenicity, nor vascular toxicity in zebrafish under the concentrations range from 2.5 μΜ to 40 μM. Importantly, these results provide new lead compounds for the development of antidiabetes strategies.

NMR-based metabolomics applied to ecotoxicology with zebrafish (Danio rerio) as a prominent model for metabolic profiling and biomarker discovery: Overviewing the most recent approaches

Metabolomics is an innovative approach used in the medical, toxicological, and biological sciences. As an interdisciplinary topic, metabolomics and its relation with the environment and toxicological research are extensive. The use of substances, such as drugs and pesticides, contributes to the continuous releasing of xenobiotics into the environment, harming organisms and their habitats. In this context, fish are important bioindicators of the environmental condition and have often been used as model species. Among them, zebrafish (Danio rerio) presents itself as a versatile and straightforward option due to its unique attributes for research. Zebrafish proves to be a valuable model for toxicity assays and also for metabolomics profiling by analytical tools. Thus, NMR-based metabolomics associated with statistical analysis can reasonably assist researchers in critical factors related to discovering and validating biomarkers through accurate diagnosis. Therefore, this review aimed to report the studies that applied zebrafish as a model for (eco)toxicological assays and essentially utilized NMR-based metabolomics analysis to assess the biochemical profile and thus suggest the potential biological marker.

Healing Wounds Efficiently with Biomimetic Soft Matter: Injectable Self-Healing Neutral Glycol Chitosan/Dibenzaldehyde-Terminated Poly(ethylene glycol) Hydrogel with Inherent Antibacterial Properties

The high prevalence of acquiring skin wounds, along with the emergence of antibiotic-resistant strains that lead to infections, impose a threat to the physical, mental, and socioeconomic health of society. Among the wide array of wound dressings developed, hydrogels are regarded as a biomimetic soft matter of choice owing to their ability to provide a moist environment ideal for healing. Herein, neutral glycol chitosan (GC) was cross-linked via imine bonds with varying concentrations of dibenzaldehyde-terminated polyethylene glycol (DP) to give glycol chitosan/dibenzaldehyde-terminated polyethylene glycol hydrogels (GC/DP). These dynamic Schiff base linkages (absorption peak at 1638 cm^-1) within the hydrogel structure endowed their ability to recover from damage as characterized by high-low strain exposure in continuous step strain rheology. Along with their good injectability and biodegradability, the hydrogels exhibited remarkable inhibition against E. coli, P. aeruginosa, and S. aureus. GC/DP hydrogels demonstrated high LC50 values in vivo using zebrafish embryos as a model system due to their relative biocompatibility and a remarkable 93.4 ± 0.88% wound contraction at 30-dpw against 49.1 ± 3.40% of the control. To the best of our knowledge, this is the first study that developed injectable glycol chitosan/dibenzaldehyde-terminated polyethylene glycol self-healing hydrogels for application in wound healing with intrinsic bacteriostatic properties against the three bacteria.

Azaphilones from the Endophyte Diaporthe sp. and Their Toxicity

Chemotherapy and targeted therapies are increasingly used as conventional means to control tumor growth and prolong survival. Patient treated with anti-neoplastic agents experience severe side effects, especially those cytotoxic chemotherapies. Exploring chemo agents with less side effects is the hot spot of anticancer research. In this study, three azaphilone derivatives (chaetoviridin A (1), chaetoviridin E (2) and chaetomugilin D (3)) were isolated from the endophyte of the plant Anoectochilus roxburghii (Wall.) Lindl, their structures were elucidated by NMR. The toxicity of these compounds was evaluated by zebrafish model. The results show that these compounds had no toxicity against zebrafish. These compounds may act as safe anticancer drug leads according to this result. These three azaphilone derivatives were first time reported isolated from Diaporthe species which mainly used to isolate from Chaetomium species.

Toxicity Mitigation of Textile Dye Reactive Blue 4 by Hairy Roots of Helianthus annuus and Testing Its Effect in In Vivo Model Systems

An anthraquinone textile dye, Reactive Blue 4 (RB4), poses environmental health hazards. In this study, remediation of RB4 (30-110 ppm) was carried out by hairy roots (HRs). UV-visible spectroscopy and FTIR analysis showed that the dye undergoes decolourization followed by degradation. In addition, toxicity and safety analyses of the bioremediated dye were performed on Allium cepa and zebrafish embryos, which revealed lesser toxicity of the bioremediated dye as compared to untreated dye. For Allium cepa, the highest concentration, i.e., 110 ppm of the treated dye, showed less chromosomal aberrations with a mitotic index of 8.5 ± 0.5, closer to control. Two-fold decrease in mortality of zebrafish embryos was observed at the highest treated dye concentration indicating toxicity mitigation. A higher level of lipid peroxidation (LPO) was recorded in the zebrafish embryo when exposed to untreated dye, suggesting a possible role of oxidative stress-inducing mortality of embryos. Further, the level of LPO was significantly normalized along with the other antioxidant enzymes in embryos after dye bioremediation. At lower concentrations, mitigated samples displayed similar antioxidant activity comparable to control underlining the fact that the dye at lesser concentration can be more easily degraded than the dye at higher concentration.

Chemical Characterization, Antibacterial Activity, and Embryo Acute Toxicity of Rhus coriaria L. Genotype from Sicily (Italy)

This study reports a full characterization of the Sicilian sumac, Rhus coriaria L. This fruit represents a potential source of fiber (33.21 ± 1.02%) and unsaturated fatty acids, being the contents of linoleic and α-linolenic acids, 30.82 ± 1.21% and 1.85 ± 0.07%, respectively. In addition, the content of phenolic and total anthocyanin was 71.69 ± 1.23 mg/g as gallic acid equivalents, and 6.71 ± 0.12 mg/g as cyanidin-3-O-glucoside equivalents, respectively. The high content in mineral elements, consisting mainly of potassium, calcium, magnesium, and phosphorus, followed by aluminum, iron, sodium, boron, and zinc, was detected by inductively coupled plasma mass spectrometry (ICP-MS). Moreover, its antimicrobial activity was evaluated against multidrug resistant (MDR) microorganisms, represented by Escherichia coli and Klebsiella pneumoniae strains isolated from poultry. The activity of seven different sumac fruit extracts obtained using the following solvents—ethanol (SE), methanol (SM), acetone (SA), ethanol and water (SEW), methanol and water (SMW), acetone and water (SAW), water (SW)—was evaluated. The polyphenol profile of SM extract, which showed better activity, was analyzed by ultra-high performance liquid chromatography coupled with mass spectrometry (UHPLC-MS). The major component identified was gallic acid, followed by quercetin, methyl digallate, pentagalloyl-hexoside, and kaempferol 3-O-glucoside. The non-toxicity of Sicilian R. coriaria was confirmed by testing the effect of the same extract on zebrafish embryos.

Alternative animal models in predictive toxicology

Toxicity testing relies heavily on animals, especially rodents as part of the non-clinical laboratory testing of substances. However, the use of mammalians and the number of animals employed in research has become a concern for institutional ethics committees. Toxicity testing involving rodents and other mammals is laborious and costly. Alternatively, non-rodent models are used as replacement, as they have less ethical considerations and are cost-effective. Of the many alternative models that can be used as replacement models, which ones can be used in predictive toxicology? What is the correlation between these models and rodents? Are there standardized protocols governing the toxicity testing of these commonly used predictive models? This review outlines the common alternative animal models for predictive toxicology to address the importance of these models, the challenges, and their standard testing protocols.

Design of Hepatic Targeted Drug Delivery Systems for Natural Products: Insights into Nomenclature Revision of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD), recently renamed metabolic-dysfunction-associated fatty liver disease (MAFLD), affects a quarter of the worldwide population. Natural products have been extensively utilized in treating NAFLD because of their distinctive advantages over chemotherapeutic drugs, despite the fact that there are no approved drugs for therapy. Notably, the limitations of many natural products, such as poor water solubility, low bioavailability in vivo, low hepatic distribution, and lack of targeted effects, have severely restricted their clinical application. These issues could be resolved via hepatic targeted drug delivery systems (HTDDS) that boost clinical efficacy in treating NAFLD and decrease the adverse effects on other organs. Herein an overview of natural products comprising formulas, single medicinal plants, and their crude extracts has been presented to treat NAFLD. Also, the clinical efficacy and molecular mechanism of active monomer compounds against NAFLD are systematically discussed. The targeted delivery of natural products via HTDDS has been explored to provide a different nanotechnology-based NAFLD treatment strategy and to make suggestions for natural-product-based targeted nanocarrier design. Finally, the challenges and opportunities put forth by the nomenclature update of NAFLD are outlined along with insights into how to improve the NAFLD therapy and how to design more rigorous nanocarriers for the HTDDS. In brief, we summarize the up-to-date developments of the NAFLD-HTDDS based on natural products and provide viewpoints for the establishment of more stringent anti-NAFLD natural-product-targeted nanoformulations.

In Vitro and In Vivo Toxicity Evaluation of Natural Products with Potential Applications as Biopesticides

The use of natural products in agriculture as pesticides has been strongly advocated. However, it is necessary to assess their toxicity to ensure their safe use. In the present study, mammalian cell lines and fish models of the zebrafish (Danio rerio) and medaka (Oryzias latipes) have been used to investigate the toxic effects of ten natural products which have potential applications as biopesticides. The fungal metabolites cavoxin, epi-epoformin, papyracillic acid, seiridin and sphaeropsidone, together with the plant compounds inuloxins A and C and ungeremine, showed no toxic effects in mammalian cells and zebrafish embryos. Conversely, cyclopaldic and α-costic acids, produced by Seiridium cupressi and Dittrichia viscosa, respectively, caused significant mortality in zebrafish and medaka embryos as a result of yolk coagulation. However, both compounds showed little effect in zebrafish or mammalian cell lines in culture, thus highlighting the importance of the fish embryotoxicity test in the assessment of environmental impact. Given the embryotoxicity of α-costic acid and cyclopaldic acid, their use as biopesticides is not recommended. Further ecotoxicological studies are needed to evaluate the potential applications of the other compounds.

24-Epibrassinolide modulates the neurodevelopmental outcomes of high caffeine exposure in zebrafish (Danio rerio) embryos

Previous embryonic fish data have shown caffeine to induce potential teratogenic and long-term neurodevelopmental outcomes through oxidative stress-mediated apoptosis. In this context, antioxidants may have the potential to counteract the caffeine-induced effects. Therefore, the present study aimed to investigate the potential protective role of 24-epibrassinolide (24-EPI), a natural brassinosteroid with proven antioxidant properties, against caffeine-induced teratogenic effects during early zebrafish development. Embryos (~2 h post-fertilization - hpf) were exposed to 0.5 mM caffeine, co-exposed to 24-EPI (0.01, 0.1 and 1 μM) and to 24-EPI alone (1 μM) for 96 h. During exposure, lethal and sublethal developmental parameters were evaluated. At the end of the exposure, biochemical evaluations were made, and 24 h after, different behavioural paradigms were assessed. An increased number of animals showing oedema and malformations were observed after caffeine exposure, while these were reduced after co-exposure to 24-EPI concentration, namely the tail curvature. The results showed oxidative stress and related parameters similar among treatments. Yet, caffeine exposure resulted in locomotor deficits (decreased speed and distance) and disrupted anxiety-like and avoidance responses. The co-exposure to caffeine and to the highest 24-EPI concentrations resulted in less pronounced behavioural deficits. Overall, there was an absence of effects in the embryo/larvae exposed solely to 24-EPI, while caffeine caused developmental and neurotoxic effects. Although further studies are needed, the results showed promising protective effects of the highest 24-EPI concentration tested against the toxicity induced by caffeine in zebrafish.

Cadmium significantly changes major morphometrical points and cardiovascular functional parameters during early development of zebrafish

Living organisms are commonly exposed to cadmium and other toxic metals. A vast body of research has shown the significant effects of these toxic metals on developmental processes. In order to study the role of toxic metals on early developmental stages of eukaryotes, we explored the effect of cadmium (Cd²⁺) contaminant on zebrafish. Thus, zebrafish embryos were exposed to 3 mg/L (16.7 μM) Cd²⁺ for 96 h and imaged every 24 h from the exposure onwards. Hatching rates of the eggs were determined at 72 h, followed by analyses at 96 h for: survival rate, morphometrical factors, and functional parameters of the cardiovascular system. Interestingly enough, significant hatching delays along with smaller cephalic region and some morphological abnormalities were observed in the treatment group. Moreover, substantial changes were noticed in the length of notochord and embryo, absorption of yolk sac with shorter extension, area of swimming bladder, as well as pericardium sac after Cd²⁺ treatment. Cadmium also caused significant abnormalities in heart physiology which could be the leading cause of mentioned morphological deformities. Herein, our results shine light on systematic acute embryological effects of cadmium in the early development of zebrafish for the first time.

Preliminary Insight of Pyrrolylated-Chalcones as New Anti-Methicillin-Resistant Staphylococcus aureus (Anti-MRSA) Agents

Bacterial infections are regarded as one of the leading causes of fatal morbidity and death in patients infected with diseases. The ability of microorganisms, particularly methicillin-resistant Staphylococcus aureus (MRSA), to develop resistance to current drugs has evoked the need for a continuous search for new drugs with better efficacies. Hence, a series of non-PAINS associated pyrrolylated-chalcones (1–15) were synthesized and evaluated for their potency against MRSA. The hydroxyl-containing compounds (8, 9, and 10) showed the most significant anti-MRSA efficiency, with the MIC and MBC values ranging from 0.08 to 0.70 mg/mL and 0.16 to 1.88 mg/mL, respectively. The time-kill curve and SEM analyses exhibited bacterial cell death within four hours after exposure to 9, suggesting its bactericidal properties. Furthermore, the docking simulation between 9 and penicillin-binding protein 2a (PBP2a, PDB ID: 6Q9N) suggests a relatively similar bonding interaction to the standard drug with a binding affinity score of −7.0 kcal/mol. Moreover, the zebrafish model showed no toxic effects in the normal embryonic development, blood vessel formation, and apoptosis when exposed to up to 40 µM of compound 9. The overall results suggest that the pyrrolylated-chalcones may be considered as a potential inhibitor in the design of new anti-MRSA agents.

Phytochemical and Safety Evaluations of Zingiber ottensii Valeton Essential Oil in Zebrafish Embryos and Rats

Zingiber ottensii Valeton (ZO) exhibits pharmacological activity and has long been used in traditional medicine. However, reports about its safety profiles are limited. The present study aimed to evaluate the phytochemical profile and the toxic effects of ZO essential oil on the development of zebrafish and acute oral toxicity in rats. The essential oil was isolated from ZO rhizomes, and phytochemicals were analyzed using a gas chromatography-mass spectrometer (GC-MS). The embryotoxic and teratogenic effects of ZO essential oil were evaluated in zebrafish embryos and larvae and the acute oral toxicity was determined in rats. GC-MS results showed the essential oil contained zerumbone as a major phytoconstituent (24.73%). The zebrafish embryotoxicity of ZO essential oil appeared to be concentration- and time-dependent manner, with a moderate LC₅₀ (1.003 µg/mL). Teratogenicity in zebrafish embryos also included morphological defects, decreased hatchability, and reduced heart rate. In rats, ZO essential oil (2000 mg/kg, p.o.) resulted in no mortality or significant toxicities. These findings suggest that ZO has embryotoxic and teratogenic effects in zebrafish embryos but does not result in death or acute oral toxicity in rats. Further long-term toxicity studies are needed to confirm the safety of products developed from ZO essential oil.

The Reproductive Toxicity Associated with Dodonaea viscosa, a Folk Medicinal Plant in Saudi Arabia

Dodonaea viscosa is a medicinal plant which is being used to treat various diseases in humans. The available safety data suggest that the plant does not produce any side effects, or toxicity, in tested adult experimental animals. However, the influence of D. viscosa on fetus or embryonic development is largely not known. This study was conducted in order to find out the reproductive toxicity of D. viscosa in experimental animals. Zebrafish embryos were used as the in vivo developmental toxicity animal model. Methanolic crude extract, hexane, chloroform, and butanol fractions were prepared from the leaves of D. viscosa. Zebrafish embryos were exposed to serial dilution of crude extract and other fractions. The crude extract and hexane fraction induced higher level of toxicity in zebrafish embryos as compared to chloroform and butanol fractions. The phenol and flavonoid estimation revealed that crude leaves extract and hexane fractions had lower content of phenol and flavonoid. Two major compounds, phytol and methyl ester, of hexadecanoic acid were identified by gas chromatography and mass spectrophotometry (GC-MS) analysis. More detailed studies are needed to check the toxicity of D. viscosa in pregnant experimental animals; however, the results from this study have shown that D. viscosa possesses reproductive toxicity and its use and doses must be carefully monitored in pregnant patients.

Toxicological assessment of a bioactive extract from Triplaris gardneriana Wedd. seeds using alternative models

The Triplaris gardneriana Wedd. seeds extract has great therapeutic potential due to numerous biological activities such as antioxidant, antibacterial and anti-inflammatory, which are associated with phenolic content. Although this herbal preparation has shown many benefits, recently their toxicity profile has begun to be explored. In this present study, the toxic effects of T. gardneriana seeds ethanolic extract (EETg) on biological systems of different taxonomical groups and levels of complexity (from cell culture to lower vertebrates) were assessed, through a variety of viability and toxicological assays. It was found that EETg did not impair the Saccharomyces cerevisiae growth at the highest tested concentration (200 µg/mL), and no toxicant evidence was observed in Aedes aegypti larvae or in Drosophila melanogaster adult stage. Contrarily, the extract reduced the viability of undifferentiated Caco-2 cells (250 µg/mL, 40% of viable cells), but did not affect differentiated ones. The embryotoxicity in Danio rerio model showed a LC₅₀ of 7.41 mg/L (95% confidence interval, 4.78 - 11.49 mg/L). EETg did not show signs of toxicity in the majority of the models used, but lethality and malformations in zebrafish embryos occurred. Further analyses are needed to better understand the selective toxicity mechanism of EETg on zebrafish, as well as whether the toxic effects happen in higher vertebrates.

Antibacterial activity of Lemna minor extracts against Pseudomonas fluorescens and safety evaluation in a zebrafish model

The treatment of bacterial diseases in aquaculture is done using antibiotics, their applications has resulted in contamination and bacterial resistance. Natural extracts are a potential alternative as an antimicrobial, they have demonstrated effectiveness in their use aimed at treating conditions. The purpose of this study was to evaluate the antimicrobial activity of Lemna minor extracts against Pseudomonas fluorescens with different solvent for extraction. Methanol, chloroform and hexane were used. Subsequently, the safety assessment of the extracts in Danio rerio embryos and larvae was performed to validate as ecologically harmless. Antibacterial activity was detected in three extracts with significant differences (p = 0.001). Hexane extract had the highest antibacterial activity, followed by chloroform and methanol extracts. The three extracts have differences with respect to the control, between times and concentrations tested (p = 0.001). Minimum inhibitory concentration values (MIC) at 24 h methanolic extract ME 0.05 µg mL-1. In embryos and larvae increased safety of the LC50 methanolic extract was evidenced followed by the hexane and chloroform extract. No morphological or tissue changes were observed in embryos and larvae. The hexane extracts of L. minor had a greater bactericidal effect against P. fluorescens and are functional because of their antibacterial activity, but methanolic extract is more safety in embryos and larvae of D. rerio, making it a potential alternative for use in the treatment and control of septicemia in fish.

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.

Nano-emulsification of Aeollanthus suaveolens Mart. Ex Spreng essential oil modifies its neuroeffects?

Oil in water nano-emulsions are drug delivery systems constituted by liquid lipophilic nano-droplets dispersed through the external aqueous phase, often reaching the kinetic stability with surfactant as stabilizers. Essential oils can be the oily phase or the source of bioactive compounds. In this study, the essential oil of Aeollanthus suaveolens-a plant used in folk medicine due to its psychopharmacological effects-was used for preparation of fine nano-emulsions by a low-energy titrating method. Monodisperse small nano-droplets (ca. 70 nm; PdI 0.200) were assembled by using blends of non-ionic surfactants, indicating modulation on surfactant system lead to altering the physical property. In a separate set of experiments, we investigated the role of this modulation on biological properties of the optimal nano-emulsion. The zebrafish embryos were more susceptible to the nano-emulsion than the bulk essential oil, showing the improved bioactivity due to nano-sizing. Therefore, adult zebrafish was treated, and paralysis was observed in the groups treated with the nano-emulsion, being this finding in accordance with hypnosis. At the same essential oil dose, another behavior was observed, suggesting that expected dose-dependent effects associated to sedative-hypnotics can be achieved by nano-sizing of psychoactive essential oils. This paper contributes to the state-of-art drug delivery systems by opening perspectives for novel sedative-hypnotics nano-emulsified essentials oils that can reach hypnotic effects at considerably lower dose, when compared with bulk materials, being useful for further completed dose-response studies.Graphical abstract.

Validation of in-vitro bioassay methods: Application in herbal drug research

This present review described the validation method of in-vitro bioassay for its application in herbal drug research. Seven sequencing steps that can be taken for performing a valid bioassay include: literature survey, sample stability evaluation, Biosystem performance testing, Sample performance evaluation, determination of 50% effective concentration or cytotoxic concentrations, selective index evaluation, and determination of accurate relative potency of sample. Detailed methods and acceptance criteria for each step are described herein. Method calculations of the relative potency of sample using European Pharmacopeia 10.0, 5.3 (2020) were recommended instead of using United States Pharmacopeia 42 (2019). For having reliable data and conclusions, all methods (chemical and bioassay) need to be first validated before any data collection. Absence of any validation method may results in incorrect conclusions and bias.