Gluc-HET, a complementary chick embryo model for the characterization of antidiabetic compounds

Aluminium oxide nanoparticles (Al2O3-NPs) exposure impairs cardiovascular physiology and elevates health risk - proteomic and molecular mechanistic insights

The interactions of nanoparticles with biomolecules lead to toxicopathological outcomes through various mechanisms including oxidative stress. In this regard, the interplay of oxidative stress with other molecular mechanisms of cytotoxicity during aluminium oxide nanoparticles (Al2O3-NPs) induced cardiovascular toxicity was not yet precisely explored. Initially, the human serum protein interaction and its corona composition were explored through the gel/label-free proteomics (nLC-HRMS/MS) method. In addition, endothelial cells (EC) and cardiomyoblasts (CM) cultures were employed along with various oxidative stress and cell stress assays. Further, various expression studies (RT-qPCR, western blot, and immunofluorescence), kinase signalling, and siRNA mediated gene knockout assays were performed. Alongside, the in ovo impact on antioxidant enzymes and metabolomic pathways (1H NMR) in the heart validated the role of oxidative stress during cardiotoxicity. The current outcome illustrates the dose-dependent increase of cytotoxicity and caspase (3 and 9) activation. The dose-dependent elevation and its synergy with cardiovascular stress signalling (ET-1 and Ang-II) illustrate the prominent role of oxidative stress during toxicity. In conclusion, the current study connects the role of the redox system and molecular stress pathways during Al2O3-NPs induced cardiotoxicity which extends the knowledge towards the precise health risk assessment during human exposure.

Identification of Plant Phenolics from Paulownia tomentosa and Morus alba as Novel PPARγ Partial Agonists and Hypoglycemic Agents

The aim of our study was to determine the PPARγ agonism and hypoglycemic activity of natural phenolics isolated from Paulownia tomentosa and Morus alba. We started with a molecular docking preselection, followed by in vitro cell culture assays, such as PPARγ luciferase reporter gene assay and PPARγ protein expression by Western blot analysis. The ability of the selected compounds to induce GLUT4 translocation in cell culture and lower blood glucose levels in chicken embryos was also determined. Among the thirty-six plant phenolic compounds, moracin M showed the highest hypoglycemic effect in an in ovo experiment (7.33 ± 2.37%), followed by mulberrofuran Y (3.84 ± 1.34%) and diplacone (3.69 ± 1.37%). Neither moracin M nor mulberrofuran Y showed a clear effect on the enhancement of GLUT4 translocation or agonism on PPARγ, while diplacone succeeded in both (3.62 ± 0.16% and 2.4-fold ± 0.2, respectively). Thus, we believe that the compounds moracin M, mulberrofuran Y, and diplacone are suitable for further experiments to elucidate their mechanisms of action.

Primordial germ cells as a potential model for understanding (Nutri) epigenetic - metabolic interactions: a mini review

Primordial germ cells (PGCs) are the progenitors of gametes (sperm and eggs), making them crucial for understanding germline transmission and epigenetic modifications, which are critical for studying transgenerational effects of nutrition and metabolic diseases. This is particularly relevant given the growing evidence that environmental factors, such as diet, can influence metabolic disease risk across generations through modulating epigenetic mechanisms, as seen in both human and animal studies. The unique biological and experimental attributes make PGCs in the chicken embryo a potential model for exploring the complex interactions between nutrition, epigenetic inheritance, and metabolic diseases, providing insights that are translatable to metabolic health and disease prevention tactics. This brief review emphasizes the potential of chicken PGCs as a model system to investigate the mechanisms underlying transgenerational metabolic programming.

Human circulatory proteome interaction, oxidative stress-associated signalling and cardiovascular implications during titanium dioxide nanoparticle (TiO2-NP) exposure

The increasing exposure to nanoparticles raises a concern over their toxicity. Incidentally, reactive oxygen species (ROS) are produced as a result of the nanoparticle's physicochemical characteristics and interactions with intracellular elements, primarily enzymes, leading to oxidative stress. In this context, the extent of oxidative stress resulting from the toxicity of titanium dioxide nanoparticles (TiO2-NPs) on the cardiovascular system has not yet been thoroughly investigated. Initially, the gel/label-free proteomics (nLC-HRMS/MS) method was used to examine human serum protein interaction and corona composition. Furthermore, different oxidative stress assays (superoxide, total ROS, mitochondrial ROS, and lipid peroxidation) and cell stress assays (apoptosis, ER stress, mitochondrial dysfunction, autophagy, and hypertrophy) were performed in conjunction with endothelial (rat aortic cells) and cardiomyoblast (H9c2) cell cultures. In addition, expression studies (RT-qPCR and immunofluorescence), kinase signalling, and siRNA-mediated gene knockout (NOX2 and XO) studies were conducted. Alongside, in ovo effects on the heart's antioxidant enzymes (SOD and CAT) and metabolomic pathways (1H NMR) confirmed the involvement of oxidative stress in cardiotoxicity. The present results demonstrate a dose-dependent increase in cytotoxicity via the activation of caspase 3 and 9. The dose-dependent increase and its synergistic relationship with cardiovascular stress signalling (ET-1 and Ang-II) highlight the significant role of oxidative stress in nanoparticle toxicity. In summary, this study expands our understanding of the precise health risks associated with human exposure by establishing a connection between the role of the redox system and molecular stress pathways in TiO2-NPs-induced cardiotoxicity.

Short-term exposure of 2.4 GHz electromagnetic radiation on cellular ROS generation and apoptosis in SH-SY5Y cell line and impact on developing chick embryo brain tissue

BACKGROUND

Electromagnetic radiation (EMR) from wireless technology and mobile phones, operates at various frequencies. The present study analyses the major impact of short-term exposure to 2.4 GHz frequency EMR, using the two model systems chick embryos and SH-SY5Y cell lines. We hypothesized that exposure to this frequency would induce oxidative stress and apoptosis in neurons.

METHODS AND RESULTS

Chick embryos were exposed continuously to 2.4 GHz EMR for 4 h each day over a 5-day period, and comparisons were made with a control group. At the end of the exposure, brain tissues were dissected for histopathological analysis, antioxidant assays, and reactive oxygen species (ROS) detection. Additionally, SH-SY5Y cells were exposed to 2.4 GHz EMR to assess cell viability, DNA damage, and apoptosis. Our results showed that exposure to 2.4 GHz EMR induces oxidative stress in both chick embryos and the SH-SY5Y cells, though no significant tissue-level impact was observed. In SH-SY5Y cells, ROS production increased after 4 h of exposure, accompanied by moderate DNA damage and early markers of apoptosis, such as upregulation of the Bax gene. Furthermore, we observed that antioxidants, such as NAC and Mito-TEMPO, helped mitigate the cytotoxic effects of EMR in both the study models.

CONCLUSION

In conclusion, short-term exposure (4 h) to 2.4 GHz EMR induced moderate cellular and molecular changes, primarily oxidative stress. The oxidative stress was reduced by antioxidants, which suggests potential benefits in preventing EMR-induced cytotoxicity. Extended exposure to EMR beyond 4 h may pose adverse health risks to humans, endorsing further investigation.

Insulin-Mimetic Activity of Herbal Extracts Identified with Large-Scale Total Internal Reflection Fluorescence Microscopy

Diabetes mellitus is a spreading global pandemic. Type 2 diabetes mellitus (T2DM) is the predominant form of diabetes, in which a reduction in blood glucose uptake is caused by impaired glucose transporter 4 (GLUT4) translocation to the plasma membrane in adipose and muscle cells. Antihyperglycemic drugs play a pivotal role in ameliorating diabetes symptoms but often are associated with side effects. Hence, novel antidiabetic compounds and nutraceutical candidates are urgently needed. Phytogenic therapy can support the prevention and amelioration of impaired glucose homeostasis. Using total internal reflection fluorescence microscopy (TIRFM), 772 plant extracts of an open-access plant extract library were screened for their GLUT4 translocation activation potential, resulting in 9% positive hits. Based on commercial interest and TIRFM assay-based GLUT4 translocation activation, some of these extracts were selected, and their blood glucose-reducing effects in ovo were investigated using a modified hen's egg test (Gluc-HET). To identify the active plant part, some of the available candidate plants were prepared in-house from blossoms, leaves, stems, or roots and tested. Acacia catechu (catechu), Pulmonaria officinalis (lungwort), Mentha spicata (spearmint), and Saponaria officinalis (common soapwort) revealed their potentials as antidiabetic nutraceuticals, with common soapwort containing GLUT4 translocation-activating saponarin.

A comprehensive in-vitro/in-vivo screening toolbox for the elucidation of glucose homeostasis modulating properties of plant extracts (from roots) and its bioactives

Plant extracts are increasingly recognized for their potential in modulating (postprandial) blood glucose levels. In this context, root extracts are of particular interest due to their high concentrations and often unique spectrum of plant bioactives. To identify new plant species with potential glucose-lowering activity, simple and robust methodologies are often required. For this narrative review, literature was sourced from scientific databases (primarily PubMed) in the period from June 2022 to January 2024. The regulatory targets of glucose homeostasis that could be modulated by bioactive plant compounds were used as search terms, either alone or in combination with the keyword "root extract". As a result, we present a comprehensive methodological toolbox for studying the glucose homeostasis modulating properties of plant extracts and its constituents. The described assays encompass in-vitro investigations involving enzyme inhibition (α-amylase, α-glucosidase, dipeptidyl peptidase 4), assessment of sodium-dependent glucose transporter 1 activity, and evaluation of glucose transporter 4 translocation. Furthermore, we describe a patch-clamp technique to assess the impact of extracts on KATP channels. While validating in-vitro findings in living organisms is imperative, we introduce two screenable in-vivo models (the hen's egg test and Drosophila melanogaster). Given that evaluation of the bioactivity of plant extracts in rodents and humans represents the current gold standard, we include approaches addressing this aspect. In summary, this review offers a systematic guide for screening plant extracts regarding their influence on key regulatory elements of glucose homeostasis, culminating in the assessment of their potential efficacy in-vivo. Moreover, application of the presented toolbox might contribute to further close the knowledge gap on the precise mechanisms of action of plant-derived compounds.

Investigating the teratogenic potential of diclofenac sodium on chick embryos: A warning for pregnant women

Teratogenic and embryotoxic effect of diclofenac sodium (DS) on different developmental stages of the chick-embryos was investigated by examining different parameters such as its mortality rate, hatching, morphological measurements, weighing its internal organs and calculation of different indices. Experiment was divided into four trials with different dose (0.1 mL, 0.2 mL, 0.3 mL in groups A, B, and C, respectively and group D received 0.3 mL saline solution (0.9% NaCl) and group E remained un-injected) administration and observation. Results of first and second trial showed statistically (p<0.01) significant difference in bodyweight, body-length, forelimb and hindlimb length between experimental and control groups. In third trial, diclofenac sodium administration showed a statistically (p<0.01) significant difference in the bodyweight, body-length, forelimb, hindlimb length, liver weight, egg weight (EE ratio) and kidney somatic index (KSI). The beak-size, heart weight, kidney weight, cardiac somatic index (CSI) and hepato somatic index (HSI) were not significant (p>0.05) when compared with the control groups. In trial 4, forelimb, hindlimb length, heart weight, CSI and HSI were statistically (p<0.01) significant. Body-length and liver weight were significant (p<0.05). While bodyweight, beak size, kidney weight and KSI were non-significant (p>0.05). The mortality rate was increased with increase dose of DS and also affected the hatching. DS effect on chick embryos can be applied to humans because the early development of mammals and birds are closely related. So, it was concluded that DS should be used with caution during pregnancy especially during first trimester of pregnancy.

Formulation and Characterization of Epalrestat-Loaded Polysorbate 60 Cationic Niosomes for Ocular Delivery

The aim of this work was to develop niosomes for the ocular delivery of epalrestat, a drug that inhibits the polyol pathway and protects diabetic eyes from damage linked to sorbitol production and accumulation. Cationic niosomes were made using polysorbate 60, cholesterol, and 1,2-di-O-octadecenyl-3-trimethylammonium propane. The niosomes were characterized using dynamic light scattering, zeta-potential, and transmission electron microscopy to determine their size (80 nm; polydispersity index 0.3 to 0.5), charge (-23 to +40 mV), and shape (spherical). The encapsulation efficiency (99.76%) and the release (75% drug release over 20 days) were measured with dialysis. The ocular irritability potential (non-irritating) was measured using the Hen's Egg Test on the Chorioallantoic Membrane model, and the blood glucose levels (on par with positive control) were measured using the gluc-HET model. The toxicity of the niosomes (non-toxic) was monitored using a zebrafish embryo model. Finally, corneal and scleral permeation was assessed with the help of Franz diffusion cells and confirmed with Raman spectroscopy. Niosomal permeation was higher than an unencapsulated drug in the sclera, and accumulation in tissues was confirmed with Raman. The prepared niosomes show promise to encapsulate and carry epalrestat through the eye to meet the need for controlled drug systems to treat the diabetic eye.

Empagliflozin induces apoptotic-signaling pathway in embryonic vasculature: In vivo and in silico approaches via chick’s yolk sac membrane model

The present investigation was conducted to evaluate the vascular-toxicity of empagliflozin (EMP) in embryonic vasculature. Firstly, the vascular-toxicity of the drug as well as its interaction with apoptotic regulator proteins was predicted via in silico approach. In the next step, the apoptotic-signaling pathway in embryonic vasculature was evaluated using a chick’s YSM model. In silico simulation confirmed vascular-toxicity of EMP. There was also an accurate affinity between EMP, Bax and Bcl-2 (−7.9 kcal/mol). Molecular dynamics assay revealed complex stability in the human body conditions. Furthermore, EMP is suggested to alter Bcl-2 more than BAX. Morphometric quantification of the vessels showed that the apoptotic activity of EMP in embryonic vasculature was related to a marked reduction in vessel area, vessel diameter and mean capillary area. Based on the qPCR and immunohistochemistry assays, enhanced expression level of BAX and reduced expression level of Bcl-2 confirmed apoptotic responses in the vessels of the YSM. We observed that induction of an apoptotic signal can cause the embryonic defect of the vascular system following EMP treatment. The acquired data also raised suspicions that alteration in apoptotic genes and proteins in the vasculature are two critical pathways in vascular-toxicity of EMP.

An Untargeted Lipidomics Study of Acute Ischemic Stroke with Hyperglycemia Based on Ultrahigh-Performance Liquid Chromatography-Mass Spectrometry

Patients with type 2 diabetes have twice as much of the risk of acute ischemic stroke (AIS) occurrence as healthy individuals, and the AIS patients with type 2 diabetes have a higher risk of death and a poorer prognosis. This study was to investigate the interrelationship between hyperglycemia and AIS and provided a reference for blood glucose management of AIS patients. The blood glucose level of AIS patients of the present study was controlled by insulin below 180 mg/dL (standard group) and between 80 and 130 mg/dL (management group). And the fasting venous blood samples were collected for determination of blood glucose level, homeostasis model assessment of insulin resistance (HOMA-IR), peptide C, and basal insulin level. Furthermore, lipids of the blood samples were detected using metabolomics, so as to clarify the similarities and differences in metabolic patterns in AIS patients with diabetes after the intervention of different glycemic strategies. The results revealed that compared to the standard group, the blood glucose level and HOMA-IR in the management group were significantly decreased, and levels of peptide C and basal insulin level were greatly increased. Through lipidomics detection, 83, 50, and 44 types of significantly upregulated differential lipids were detected in the standard vs. normal groups, the standard vs. management groups, and the management vs. normal groups, respectively, with triacylglycerol dominated. This study preliminarily revealed metabolic differences among AIS patients with hyperglycemia after different blood glucose intervention methods, hoping to provide a theoretical basis for clinical prevention and treatment of this disease.

Al2O3 nanoparticles trigger the embryonic hepatotoxic response and potentiate TNF-α-induced apoptosis-modulatory effect of p38 MAPK and JNK inhibitors

Recent evidences illustrated that the release of aluminum oxide nanoparticles (Al₂O₃-NPs) into the biosphere may pose risk to the environment and cause adverse effects on living organisms including humans. The current study assessed the hepatotoxic effects of Al₂O₃-NPs on developing chicken embryo and cell culture models. Results demonstrated that Al₂O₃-NPs exposure causes histological abnormalities and increased the level of tissue damage markers (ALP, AST, and ALT) in the embryonic liver. Furthermore, increased oxidative stress (TBARS) and impaired function of antioxidant enzymes (SOD, CAT, and GPx) were also observed. Moreover, it adversely affects red blood cells (RBC) morphology, liver metabolism, and stress response gene expression (HO-1 and NQO-1). Dose-dependent ROS generation and cytotoxic response in addition to potentiating effect on tumor necrosis factor alpha (TNF-α)-induced apoptosis (caspase-3 activity) were also observed. Inhibition of p38 mitogen-activated protein kinase (p38 MAPK) and c-Jun N-terminal kinase (JNK) pathways modulates Al₂O₃-NPs-induced apoptosis in HepG2 cells. Novel mechanisms behind embryonic hepatotoxicity, cytotoxic potentiating effects, and possible prevention strategies have been explored.

Fluorescence Microscopy-Based Quantitation of GLUT4 Translocation

Postprandial insulin-stimulated glucose uptake into target tissue is crucial for the maintenance of normal blood glucose homeostasis. This step is rate-limited by the number of facilitative glucose transporters type 4 (GLUT4) present in the plasma membrane. Since insulin resistance and impaired GLUT4 translocation are associated with the development of metabolic disorders such as type 2 diabetes, this transporter has become an important target of antidiabetic drug research. The application of screening approaches that are based on the analysis of GLUT4 translocation to the plasma membrane to identify substances with insulinomimetic properties has gained global research interest in recent years. Here, we review methods that have been implemented to quantitate the translocation of GLUT4 to the plasma membrane. These methods can be broadly divided into two sections: microscopy-based technologies (e.g., immunoelectron, confocal or total internal reflection fluorescence microscopy) and biochemical and spectrometric approaches (e.g., membrane fractionation, photoaffinity labeling or flow cytometry). In this review, we discuss the most relevant approaches applied to GLUT4 thus far, highlighting the advantages and disadvantages of these approaches, and we provide a critical discussion and outlook into new methodological opportunities.

Avens Root (Geum Urbanum L.) Extract Discovered by Target-Based Screening Exhibits Antidiabetic Activity in the Hen's Egg Test Model and Drosophila melanogaster

Medicinal plant extracts are becoming increasingly important as an alternative for traditional drugs against diabetes mellitus (DM). For this reason, we initialized a target-based screening of 111 root extracts from an open access plant extract library (PECKISH) by ascertaining their in-vitro inhibitory efficacy on α-glucosidase. The two most active extracts Geum urbanum L. (roseroot) and Rhodiola rosea L. (avens root) were further tested for their antidiabetic activities in terms of their impact on different regulatory key points of glucose homeostasis. To this end, various enzyme- and cell culture-based in-vitro assays were employed including the determination of sodium-dependent glucose transporter 1 (SGLT1) activity in Caco-2 monolayers by Ussing chambers and of glucose transporter 4 (GLUT4) translocation in a GFP-reporter cell line. Subsequently, the antidiabetic potential of the root extracts were further evaluated in in-vivo models, namely hen’s eggs test and the fruit fly Drosophila melanogaster. Avens root extract was found to be a more potent inhibitor of the enzymes α-glucosidase and dipeptidyl peptidase-4 (DPP4) than roseroot extract. Most importantly, only avens root extract exhibited antidiabetic activity in the two in-vivo models eliciting a reduced blood glucose level in the in-ovo model and a decline of the triglyceride level in a dietary starch-induced D. melanogaster obesity model. Analyses of the polyphenolic composition of the avens root extract by HPLC revealed a high content of ellagic acid and its derivatives as well as ellagitannins such as pedunculagin, stenophyllanin, stachyurin, casuarinin and gemin A. In conclusion, avens root extract represents a promising medicinal plant that should be considered in further in-vivo studies on hyperglycemia in laboratory rodents and humans.

Exposure to zinc oxide nanoparticles (ZnO-NPs) induces cardiovascular toxicity and exacerbates pathogenesis - Role of oxidative stress and MAPK signaling

The precise toxico-pathogenic effects of zinc oxide nanoparticles (ZnO-NPs) on the cardiovascular system under normal and cardiovascular disease (CVD) risk factor milieu are unclear. In this study, we have investigated the dose-dependent effects of ZnO-NPs on developing chicken embryo and cell culture (H9c2 cardiomyoblast, HUVEC and aortic VSMC) models. In addition, the potentiation effect of ZnO-NPs on simulated risk factor conditions was evaluated using; 1. Reactive oxygen species (ROS) induced cardiac remodeling, 2. Angiotensin-II induced cardiac hypertrophy, 3. TNF-α induced HUVEC cell death and 4. Inorganic phosphate (Pi) induced aortic VSMC calcification models. The observed results illustrates that ZnO-NPs exposure down regulates vascular development and elevates oxidative stress in heart tissue. At the cellular level, ZnO-NPs exposure reduced the cell viability and increased the intracellular ROS generation, lipid peroxidation and caspase-3 activity in a dose-dependent manner in all three cell types. In addition, ZnO-NPs exposure significantly suppressed the endothelial nitric oxide (NO) generation, cardiac Ca²⁺ - ATPase activity and enhanced the cardiac mitochondrial swelling. Moreover, inhibition of p38 MAPK and JNK signaling pathways influence the cytotoxicity. Overall, ZnO-NPs exposure affects the cardiovascular system under normal conditions and it exacerbates the cardiovascular pathogenesis under selected risk factor milieu.

A novel model of early type 1 diabetes mellitus: The chick embryo air sack model

Diabetes Mellitus (DM) is a metabolic disease characterized by hyperglycemia. Chronic hyperglycemia is associated with long-term dysfunction such as retinopathy, nephropathy, neuropathy and cardiovascular diseases. These complications increase rates of death and disability worldwide. Due to the negative effects of DM on the quality of life, the mechanism and treatments of the disease should be investigated in more detail. Most of the research in diabetes is performed in experimental animals. Experimental animal models contributed to the advancement of clinical research, the development of new therapeutic approaches, the discovery of insulin and the purification of insulin. There are many animal models of DM in the literature. But there are a few DM model studies created with chick embryos. In these studies, it was seen that there were differences in STZ doses and STZ administration techniques. The objective of this study was to create a more acceptable and easier DM model. 180 specific pathogen free (SPF) fertilized chicken eggs (White Leghorn chicken) were used in this study. STZ was administered to 160 SPF eggs for an induced DM model. The remaining 20 SPF eggs were separated as a control group. We used two different DM models (Air sack model (ASM) and Chorioallantoic membrane model (CAMM)) and blood sampling technique in our study. 160 SPF eggs were divided into two groups with 80 eggs in each group, according to the model in which STZ was administered. When the relationship between blood glucose and blood insulin levels were examined, it was determined that there was a significantly strong negative correlation in the control group and ASM 1 group; and a significantly very strong negative correlation was found in the ASM 2 group and ASM 3 group. Our data indicate that the optimal STZ dose to create a DM model was 0.45 mg/egg and the best DM model was ASM. The second technique to be the best blood sampling technique for determining blood glucose levels. We believe that ASM can be used in DM studies and anti-DM drug studies in terms of its easebly, applicability, reproducibility and low cost.

Identification of Insulin-Mimetic Plant Extracts: From an In Vitro High-Content Screen to Blood Glucose Reduction in Live Animals

Type 2 diabetes mellitus (T2DM) is linked to insulin resistance and a loss of insulin sensitivity, leading to millions of deaths worldwide each year. T2DM is caused by reduced uptake of glucose facilitated by glucose transporter 4 (GLUT4) in muscle and adipose tissue due to decreased intracellular translocation of GLUT4-containing vesicles to the plasma membrane. To treat T2DM, novel medications are required. Through a fluorescence microscopy-based high-content screen, we tested more than 600 plant extracts for their potential to induce GLUT4 translocation in the absence of insulin. The primary screen in CHO-K1 cells resulted in 30 positive hits, which were further investigated in HeLa and 3T3-L1 cells. In addition, full plasma membrane insertion was examined by immunostaining of the first extracellular loop of GLUT4. The application of appropriate inhibitors identified PI3 kinase as the most important signal transduction target relevant for GLUT4 translocation. Finally, from the most effective hits in vitro, four extracts effectively reduced blood glucose levels in chicken embryos (in ovo), indicating their applicability as antidiabetic pharmaceuticals or nutraceuticals.

In vivo evidence of angiogenesis inhibition by β2-glycoprotein I subfractions in the chorioallantoic membrane of chicken embryos

The vascular network expansion and functioning are important factors affecting normal intra-uterine fetal development. This study addressed the previously reported antiangiogenic potential of beta-2-glycoprotein I (β₂GPI) in vivo in the chick embryo model of angiogenesis. The effects of two naturally occurring β₂GPI forms on the development of the chorioallantoic membrane (CAM) vessels and the chicken embryo were investigated. β₂GPI monomers and dimers were obtained by fractioned purification and characterized using SDS-PAGE, immunoblot, and ELISA. The egg exposure was performed by injection of small volumes of 2.5 µg/mL solutions of the β₂GPI subfractions. Angiogenesis was evaluated through quantitative measurements of vascular architecture parameters in the captured CAM images, using computational analysis of texture contrasts and computer vision techniques. Quantitative information was assigned to the CAM vasculature modifications. In vivo, the β₂GPI dimer completely halted the formation of CAM vessels and led to embryo death after 48 h of exposure. The β₂GPI monomer allowed the embryo to develop up to the 10th day, despite early changes of CAM vessels. The impaired normal vessel growth proceeded as a self-limited effect. The β₂GPI monomer-exposed eggs showed reduced vascularization on the 6th day of incubation, but embryos were viable on the 10th day of incubation, with ingurgitated CAM vessels implying sequelae of the angiogenesis inhibition. Both subfractions impaired CAM vasculature development. The β₂GPI dimer proved to be largely more harmful than the β₂GPI monomer. β₂GPI modification by cleavage or dimerization may play a role in angiogenesis control in vivo.

Acute, reproductive, and developmental toxicity of essential oils assessed with alternative in vitro and in vivo systems

Essential oils (EOs) have attracted increased interest for different applications such as food preservatives, feed additives and ingredients in cosmetics. Due to their reported variable composition of components, they might be acutely toxic to humans and animals in small amounts. Despite the necessity, rigorous toxicity testing in terms of safety evaluation has not been reported so far, especially using alternatives to animal models. Here, we provide a strategy by use of alternative in vitro (cell cultures) and in vivo (Caenorhabditis elegans, hen’s egg test) approaches for detailed investigation of the impact of commonly used rosemary, citrus and eucalyptus essential oil on acute, developmental and reproductive toxicity as well as on mucous membrane irritation. In general, all EOs under study exhibited a comparable impact on measured parameters, with a slightly increased toxic potential of rosemary oil. In vitro cell culture results indicated a concentration-dependent decrease of cell viability for all EOs, with mean IC₅₀ values ranging from 0.08 to 0.17% [v/v]. Similar results were obtained for the C. elegans model when using a sensitized bus-5 mutant strain, with a mean LC₅₀ value of 0.42% [v/v]. In wild-type nematodes, approximately tenfold higher LC₅₀ values were detected. C. elegans development and reproduction was already significantly inhibited at concentrations of 0.5% (wild-type) and 0.1% (bus-5) [v/v] of EO, respectively. Gene expression analysis revealed a significant upregulation of xenobiotic and oxidative stress genes such as cyp-14a3, gst-4, gpx-6 and sod-3. Furthermore, all three EOs under study showed an increased short-time mucous membrane irritation potential, already at 0.5% [v/v] of EO. Finally, GC–MS analysis was performed to quantitate the relative concentration of the most prominent EO compounds. In conclusion, our results demonstrate that EOs can exhibit severe toxic properties, already at low concentrations. Therefore, a detailed toxicological assessment is highly recommended for each EO and single intended application.

Hypolipidemic effects of herbal extracts by reduction of adipocyte differentiation, intracellular neutral lipid content, lipolysis, fatty acid exchange and lipid droplet motility

An increase in adipose tissue is caused by the increased size and number of adipocytes. Lipids accumulate in intracellular stores, known as lipid droplets (LDs). Recent studies suggest that parameters such as LD size, shape and dynamics are closely related to the development of obesity. Berberine (BBR), a natural plant alkaloid, has been demonstrated to possess anti-obesity effects. However, it remains unknown which cellular processes are affected by this compound or how effective herbal extracts containing BBR and other alkaloids actually are. For this study, we used extracts of Coptis chinensis, Mahonia aquifolium, Berberis vulgaris and Chelidonium majus containing BBR and other alkaloids and studied various processes related to adipocyte functionality. The presence of extracts resulted in reduced adipocyte differentiation, as well as neutral lipid content and rate of lipolysis. We observed that the intracellular fatty acid exchange was reduced in different LD size fractions upon treatment with BBR and Coptis chinensis. In addition, LD motility was decreased upon incubation with BBR, Coptis chinensis and Chelidonium majus extracts. Furthermore, Chelidonium majus was identified as a potent fatty acid uptake inhibitor. This is the first study that demonstrates the selected regulatory effects of herbal extracts on adipocyte function.

Insulin Mimetic Properties of Extracts Prepared from Bellis perennis

Diabetes mellitus (DM) and consequential cardiovascular diseases lead to millions of deaths worldwide each year; 90% of all people suffering from DM are classified as Type 2 DM (T2DM) patients. T2DM is linked to insulin resistance and a loss of insulin sensitivity. It leads to a reduced uptake of glucose mediated by glucose transporter 4 (GLUT4) in muscle and adipose tissue, and finally hyperglycemia. Using a fluorescence microscopy-based screening assay we searched for herbal extracts that induce GLUT4 translocation in the absence of insulin, and confirmed their activity in chick embryos. We found that extracts prepared from Bellis perennis (common daisy) are efficient inducers of GLUT4 translocation in the applied in vitro cell system. In addition, these extracts also led to reduced blood glucose levels in chicken embryos (in ovo), confirming their activity in a living organism. Using high-performance liquid chromtaography (HPLC) analysis, we identified and quantified numerous polyphenolic compounds including apigenin glycosides, quercitrin and chlorogenic acid, which potentially contribute to the induction of GLUT4 translocation. In conclusion, Bellis perennis extracts reduce blood glucose levels and are therefore suitable candidates for application in food supplements for the prevention and accompanying therapy of T2DM.

Vascular apoptosis associated with meglumine antimoniate: In vivo investigation of a chick embryo model

The vasculo-toxic effect of meglumine antimoniate (MA) was confirmed in our previous investigation. The current study investigates the association of this effect with altered VEGF-A and VEGF-R2 expression. Additional mechanisms by which MA causes vascular toxicity are not clearly understood. We hypothesized that MA may alter normal expression of apoptotic genes and cause vascular toxicity. The current investigation was designed to address this issue using a chick embryo model. Fertile chicken eggs were treated with MA and the extra-embryonic membrane (EEM) vasculature was evaluated by morphometric, molecular and immunohistochemistry assays. The results showed that MA not only altered apoptotic gene expression, but that this alteration may disturb the normal development of the vascular network and cause embryo malformation. The relative expression level of the CASP3, CASP7, CASP9, APAF1, AIF1 and TP53 genes increased in drug-exposed EEMs. In addition, IHC assay confirmed the low expression BCL2 and increased expression of Bax, which are associated with a high rate of apoptosis. We suggest that induction of an apoptotic signaling pathway can lead to vascular defects during embryo development and the consecutive cascade of events can lead to the embryo malformation.

In Vitro and In Vivo Inhibition of Intestinal Glucose Transport by Guava (Psidium Guajava) Extracts

SCOPE

Known pharmacological activities of guava (Psidium guajava) include modulation of blood glucose levels. However, mechanistic details remain unclear in many cases.

METHODS AND RESULTS

This study investigated the effects of different guava leaf and fruit extracts on intestinal glucose transport in vitro and on postprandial glucose levels in vivo. Substantial dose- and time-dependent glucose transport inhibition (up to 80%) was observed for both guava fruit and leaf extracts, at conceivable physiological concentrations in Caco-2 cells. Using sodium-containing (both glucose transporters, sodium-dependent glucose transporter 1 [SGLT1] and glucose transporter 2 [GLUT2], are active) and sodium-free (only GLUT2 is active) conditions, we show that inhibition of GLUT2 was greater than that of SGLT1. Inhibitory properties of guava extracts also remained stable after digestive juice treatment, indicating a good chemical stability of the active substances. Furthermore, we could unequivocally show that guava extracts significantly reduced blood glucose levels (≈fourfold reduction) in a time-dependent manner in vivo (C57BL/6N mice). Extracts were characterized with respect to their main putative bioactive compounds (polyphenols) using HPLC and LC-MS.

CONCLUSION

The data demonstrated that guava leaf and fruit extracts can potentially contribute to the regulation of blood glucose levels.

Embryonic toxico-pathological effects of meglumine antimoniate using a chick embryo model

Leishmaniasis is one of the diverse and neglected tropical diseases. Embryo-toxicity of drugs has always been a major concern. Chick embryo is a preclinical model relevant in the assessment of adverse effects of drugs. The current study aimed to assess embryonic histopathological disorders and amniotic fluid biochemical changes following meglumine antimoniate treatment. The alteration of vascular branching pattern in the chick’s extra-embryonic membrane and exploration of molecular cues to early embryonic vasculogenesis and angiogenesis were also quantified. Embryonated chicken eggs were treated with 75 or 150 mg/kg of meglumine antimoniate. Embryo malformations, growth retardation and haemorrhages on the external body surfaces were accompanied by histopathological lesions in the brain, kidney, liver and heart in a dose-dependent manner. Significant rise occurred in the biochemical indices of alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase and amylase in the amniotic fluid. Quantification of the extra-embryonic membrane vasculature showed that the anti-angiogenic and anti-vasculogenic effects of the drug were revealed by a significant decrease in fractal dimension value and mean capillary area. The relative expression levels of vascular endothelial growth factor A and vascular endothelial growth factor receptor 2 mRNA also significantly reduced. Concerns of a probable teratogenicity of meglumine antimoniate were established by data presented in this study. It is concluded that tissue lesions, amniotic fluid disturbance, altered early extra-embryonic vascular development and gene expression as well as the consecutive cascade of events, might eventually lead to developmental defects in embryo following meglumine antimoniate treatment. Therefore, the use of meglumine antimoniate during pregnancy should be considered as potentially embryo-toxic. Hence, physicians should be aware of such teratogenic effects and limit the use of this drug during the growing period of the fetus, particularly in rural communities. Further pharmaceutical investigations are crucial for planning future strategies.

An In Ovo Model for Testing Insulin-mimetic Compounds

Elevated blood glucose levels in type 2 diabetes mellitus (T2DM), a complex and multifactorial metabolic disease, are caused by insulin resistance and β-cell failure. Various strategies, including the injection of insulin or the usage of insulin-sensitizing drugs, were pursued to treat T2DM or at least reduce the symptoms. In addition, the application of herbal compounds has attracted increasing attention. Thus, it is necessary to find efficient test systems to identify and characterize insulin-mimetic compounds. Here we developed a modified chick embryo model, which enables testing of synthetic compounds and herbal extracts with insulin-mimetic properties. Using a fluorescence microscopy-based primary screen, which quantifies the translocation of Glucose transporter 4 (Glut4) to the plasma membrane, we were able to identify compounds, mainly herbal extracts, which lead to an increase of intracellular glucose concentrations in adipocytes. However, the efficacy of these substances requires further verification in a living organism. Thus, we used an in-ovo approach to identify their blood glucose-reducing properties. The approval by an ethics committee is not needed since the use of chicken embryos during the first two-thirds of embryonic development is not considered an animal experiment. Here, the application of this model is described in detail.