Ebulin from dwarf elder (Sambucus ebulus L.): a mini-review

New Light on Plants and Their Chemical Compounds Used in Polish Folk Medicine to Treat Urinary Diseases

This review contains the results of Polish (Central Europe) ethnomedical studies that describe the treatment of urinary tract diseases with wild and cultivated plants. The study includes only the plants that are used to treat the urinary tract, excluding prostate diseases. A review of the literature was carried out to verify the pharmacological use of the plants mentioned in the interviews. Based on this, the study reviews the pharmacological activities of all the recorded species and indicates their most important chemical compounds. Fifty-three species (belonging to 30 families) were selected for the study. The Compositae (eight species), Rosaceae (six species), and Apiaceae (six species) are the most common families used in the treatment of urinary diseases in Polish folk medicine. Both in vitro and in vivo studies have confirmed that many of these plant species have beneficial properties, such as diuretic, antihyperuricemic, antimicrobial, and anti-inflammatory activity, or the prevention of urinary stone formation. These effects are exerted through different mechanisms, for example, through the activation of bradykinin B2 receptors, inhibition of xanthine oxidase, or inhibition of Na+-K+ pump. Many plants used in folk medicine are rich in phytochemicals with proven effectiveness against urinary tract diseases, such as rutin, arbutin, or triterpene saponins.

Transient receptor potential channel stimulation induced oxidative stress and apoptosis in the colon of mice with colitis-associated colon cancer: modulator role of Sambucus ebulus L

BACKGROUND

Increased Ca²⁺ entry causes an increase in tumor cell proliferation, apoptosis, cytosolic reactive free oxygen species (cyROS), and mitochondrial ROS (miROS) in tumor cells. The cyROS and miROS stimulate the cation channels, including the TRPA1, TRPM2, and TRPV1. Sambucus ebulus L (SEB) (Dwarf Elder) induced both antioxidant and anticancer effects in the human hepatocarcinoma and human colon carcinoma cancer cell lines. We investigated the etiology of colorectal cancer and the impact of three channels, as well as the protective effects of SEB on apoptosis, cyROS, and miROS in the colon of mice with colitis-associated colon cancer (AOM/DSS).

METHODS

A total 28 mice were equally divided into four groups as control, SEB (100 mg/kg/day for 14 days), AOM/DSS, and SEB + AOM/DSS. Azoxymethane/dextran sulfate sodium-induced colon cancer associated with colitis was induced in the AOM/DSS groups within 10 weeks. At the end of the experiments, the colon samples were removed from the mice.

RESULTS

The protein bands of caspase - 3, TRPA1, TRPM2, and TRPV1 were increased by the treatments of AOM/DSS. The levels of apoptosis, cyROS, cleaved caspase - 3, and cleaved caspase - 9, as well as the depolarization of the mitochondrial membrane, all increased in the AOM/DSS group. Although they were reduced in the SEB and AOM/DSS + SEB groups by the treatments of SEB, TRPA1 (AP18), TRPM2 (ACA), and TRPV1 (capsazepine) antagonists, the apoptotic and oxidant values were further elevated in the AOM/DSS group by the treatments of TRPA1 (cinnamaldehyde), TRPM2 (H₂O₂), and TRPV1 (capsaicin) agonists.

CONCLUSION

The activations of TRPA1, TRPM2, and TRPV1 channels induced the increase of apoptotic and oxidant actions in the colon cancer cells, although their inhibition via SEB treatment decreased the actions. Hence, TRPA1, TRPM2, and TRPV1 activations could be used as effective agents in the treatment of colon tumors.

The Prophage and Us-Shiga Toxin Phages Revisited

The authors first met in 1998 at the University of Würzburg, Germany, at the Institute of Hygiene and Microbiology, in Helge Karch's lab, where Herbert Schmidt worked as a PostDoc and Maite Muniesa visited the lab for a postdoctoral research stay to work on phages encoding Shiga toxin 2e (Stx2e) [...].

E-N-(2-acetyl-phenyl)-3-phenyl-acrylamide targets abrin and ricin toxicity: Hitting two toxins with one stone

The efficacy of small molecule inhibitors (SMIs) against the enzymatic activity of Shiga toxin prompted the evaluation of their efficacy on related toxins viz. ricin and abrin. Ricin, like Shiga toxin, is listed as a category B bioweapon and belongs to the type II family of ribosome inactivating proteins (RIPs). Abrin though structurally and functionally similar to ricin, is considerably more toxic. In the present study, 35 compounds were evaluated in A549 cells in in vitro assays, of which 5 offered protection against abrin and 2 against ricin, with IC50 values ranging between 30.5-1379 μM and 300-341 μM, respectively. These findings are substantiated by fluorescence based thermal shift assay. Moreover, the binding of the promising compounds to the toxin components has been validated by Surface Plasmon Resonance assay and in vitro protein synthesis assay. In vivo studies reveal complete protection of mice with compound 4 E-N-(2-acetyl-phenyl)-3-phenyl-acrylamide against orally administered lethal doses of, both, abrin and ricin. The present study thus proposes the emergence of E-N-(2-acetyl-phenyl)-3-phenyl-acrylamide as a lead compound against RIPs.

Lyophyllin, a Mushroom Protein from the Peptidase M35 Superfamily Is an RNA N-Glycosidase

Ribosome-inactivating proteins (RIPs) hydrolyze the N-glycosidic bond and depurinate a specific adenine residue (A-4324 in rat 28S ribosomal RNA, rRNA) in the conserved α-sarcin/ricin loop (α-SRL) of rRNA. In this study, we have purified and characterized lyophyllin, an unconventional RIP from Lyophyllum shimeji, an edible mushroom. The protein resembles peptidase M35 domain of peptidyl-Lys metalloendopeptidases. Nevertheless, protein either from the mushroom or in recombinant form possessed N-glycosidase and protein synthesis inhibitory activities. A homology model of lyophyllin was constructed. It was found that the zinc binding pocket of this protein resembles the catalytic cleft of a classical RIP, with key amino acids that interact with the adenine substrate in the appropriate positions. Mutational studies showed that E122 may play a role in stabilizing the positively charged oxocarbenium ion and H121 for protonating N-3 of adenine. The tyrosine residues Y137 and Y104 may be used for stacking the target adenine ring. This work first shows a protein in the peptidase M35 superfamily based on conserved domain search possessing N-glycosidase activity.

Plant-made immunotoxin building blocks: A roadmap for producing therapeutic antibody-toxin fusions

Molecular farming in plants is an emerging platform for the production of pharmaceutical proteins, and host species such as tobacco are now becoming competitive with commercially established production hosts based on bacteria and mammalian cell lines. The range of recombinant therapeutic proteins produced in plants includes replacement enzymes, vaccines and monoclonal antibodies (mAbs). But plants can also be used to manufacture toxins, such as the mistletoe lectin viscumin, providing an opportunity to express active antibody-toxin fusion proteins, so-called recombinant immunotoxins (RITs). Mammalian production systems are currently used to produce antibody-drug conjugates (ADCs), which require the separate expression and purification of each component followed by a complex and hazardous coupling procedure. In contrast, RITs made in plants are expressed in a single step and could therefore reduce production and purification costs. The costs can be reduced further if subcellular compartments that accumulate large quantities of the stable protein are identified and optimal plant growth conditions are selected. In this review, we first provide an overview of the current state of RIT production in plants before discussing the three key components of RITs in detail. The specificity-defining domain (often an antibody) binds cancer cells, including solid tumors and hematological malignancies. The toxin provides the means to kill target cells. Toxins from different species with different modes of action can be used for this purpose. Finally, the linker spaces the two other components to ensure they adopt a stable, functional conformation, and may also promote toxin release inside the cell. Given the diversity of these components, we extract broad principles that can be used as recommendations for the development of effective RITs. Future research should focus on such proteins to exploit the advantages of plants as efficient production platforms for targeted anti-cancer therapeutics.

Inhibition of herpes simplex virus type 1 infection by Sambucus ebulus extract in vitro

Background: The emergence of drug-resistant strains of herpes simplex virus type 1 (HSV-1) has been increasingly reported. Therefore, attempts to discover new antiviral agents in particular from natural compounds are required. In this study, we evaluated the possible inhibitory effects of hydroalcoholic extract of Sambucus ebulus (S. ebulus ) against HSV-1. Methods: S. ebulus extract was produced by maceration method. MTT assay was used to evaluate the cytotoxicity effects of the S. ebulus extract; also, antiviral effects were measured both by test TCID50 and quantitative real-time PCR methods. To study the inhibitory impact of S. ebulus extract on the expression of HSV-1 antigens, indirect immunofluorescence assay (IFA) was also performed. All analyses were performed using the GraphPad Prism software v. 7.0. Results: In the postexposure assay of HSV-1 with S. ebulus extract at the highest nontoxic concentration (75 μg/mL), S. ebulus extract led to 2.6 log10 TCID50 reduction in infectious virus titer. At the highest nontoxic concentration, the S. ebulus extract led to inhibition rates of 91.2%, based on the quantitative real-time PCR assay results (p<0.001). Also, in the immunofluorescence assay, a significant reduction was observed in fluorescence emission intensity in HSV-1-infected cell treated with S. ebulus extract compared to the control group. Conclusion: S. ebulus extract is a novel and effective natural compound in reducing HSV-1 titer and future studies should be conducted to discover the complete mechanism of antiviral effect of this natural compound.

Immunomodulatory Activities of Sambucus javanica Extracts in DMBA-Exposed BALB/c Mouse

Purpose: Accumulating evidence shows the genus of Sambucus exerts a broad spectrum of medicinal potencies such as anticancer, antiviral, antibacterial, and antidiabetes. Based on the previous studies, we hypothesized that bioactive compounds of Sambucus might alter several biological systems, including the immune system. Therefore, this study extensively aimed to evaluate the immunomodulatory activities of Sambucus javanica extracts in 7,12-dimethylbenz[a] anthracene (DMBA)-treated BALB/c mouse. Methods: The experimental mice were orally administrated with 2.8 mg.kg-1 BW of DMBA for ten times within a month. After that, the mice were treated by S. javanica berries and leaves extracts for 2 weeks. Subsequently, the inflammation rate was evaluated by using flow cytometry analysis, whereas the necrosis incidences were observed by hematoxylin & eosin staining. Results: Based on the results, we found the expression of tumor necrosis factor alpha (TNF-α) and interferon gamma (IFN-ɣ) were increased however after treated by S. javanica berries and leaves extracts were significantly decreased. In the same way, necrosis incidence was increased in the DMBA-treated group however it was diminished with S. javanica extracts treatment. Conclusion: Together, these results suggested that S. javanica extracts have immunomodulatory activities to suppress inflammation and reduce necrosis incidence in experimental mice.

Morniga-G, a T/Tn-Specific Lectin, Induces Leukemic Cell Death via Caspase and DR5 Receptor-Dependent Pathways

Morniga-G, the Gal-specific black mulberry (Morus nigra) lectin, displays high affinity for T (CD176) and Tn (CD175) antigens, frequently expressed at the cancer cell surface. The effects of Morniga-G were investigated on a Tn-positive leukemic Jurkat cell line. The lectin, used in a concentration range between 5⁻20 μg/mL, induced cell death in leukemic Jurkat cells. Microscopic and cytofluorometric analyses indicated that Jurkat cell death was essentially apoptotic, associated with an increase in the ceramide content and a depolarization of the mitochondrial transmembrane potential. This lectin-mediated cell death was inhibited by the pan caspase-inhibitor zVAD. In addition, cleavage of caspases 8, 9, and 3 was observed in Morniga-G-treated Jurkat cells whereas Jurkat cell lines that are deficient in caspase 8⁻10, caspase 9, or FADD, survived to the lectin-mediated toxicity. Furthermore, in the presence of TRAIL- or DR5-blocking mononoclonal antibodies, Jurkat cells became resistant to Morniga-G, suggesting that the lectin triggers cell death via the TRAIL/DR5 pathway. In silico computer simulations suggest that Morniga-G might facilitate both the DR5 dimerization and the building of TRAIL/DR5 complexes. Finally, upon treatment of Jurkat cells with benzyl-GalNAc, an O-glycosylation inhibitor, a decrease in Tn antigen expression associating with a reduced Morniga-G toxicity, was observed. Taken together, these results suggest that Morniga-G induces the cell death of Tn-positive leukemic cells via concomitant O-glycosylation-, caspase-, and TRAIL/DR5-dependent pathways.

Influence of Food Matrices on the Stability and Bioavailability of Abrin

Abrin, a highly toxic plant toxin, is a potential bioterror weapon. Work from our laboratory and others have shown that abrin is highly resistant to both thermal and pH inactivation methods. We sought to evaluate the effectiveness of selected food processing thermal inactivation conditions against abrin in economically important food matrices (whole milk, non-fat milk, liquid egg, and ground beef). The effectiveness of toxin inactivation was measured via three different assays: (1) In vitro cell free translation (CFT) assay, (2) Vero cell culture cytotoxicity; and the in vivo mouse intraperitoneal (ip) bioassay. For both whole and non-fat milk, complete inactivation was achieved at temperatures of ≥80 °C for 3 min or 134 °C for 60 s, which were higher than the normal vat/batch pasteurization or the high temperature short time pasteurization (HTST). Toxin inactivation in liquid egg required temperatures of ≥74 °C for 3 min higher than suggested temperatures for scrambled eggs (22% solids) and plain whole egg. Additionally, the ground beef (80:20%) matrix was found to be inhibitory for full toxin activity in the mouse bioassay while retaining some activity in both the cell free translation assay and Vero cell culture cytotoxicity assay.

The Use of Plant-Derived Ribosome Inactivating Proteins in Immunotoxin Development: Past, Present and Future Generations

Ribosome inactivating proteins (RIPs) form a class of toxins that was identified over a century ago. They continue to fascinate scientists and the public due to their very high activity and long-term stability which might find useful applications in the therapeutic killing of unwanted cells but can also be used in acts of terror. We will focus our review on the canonical plant-derived RIPs which display ribosomal RNA N-glycosidase activity and irreversibly inhibit protein synthesis by cleaving the 28S ribosomal RNA of the large 60S subunit of eukaryotic ribosomes. We will place particular emphasis on therapeutic applications and the generation of immunotoxins by coupling antibodies to RIPs in an attempt to target specific cells. Several generations of immunotoxins have been developed and we will review their optimisation as well as their use and limitations in pre-clinical and clinical trials. Finally, we endeavour to provide a perspective on potential future developments for the therapeutic use of immunotoxins.

Plant Ribosome-Inactivating Proteins: Progesses, Challenges and Biotechnological Applications (and a Few Digressions)

Plant ribosome-inactivating protein (RIP) toxins are EC3.2.2.22 N-glycosidases, found among most plant species encoded as small gene families, distributed in several tissues being endowed with defensive functions against fungal or viral infections. The two main plant RIP classes include type I (monomeric) and type II (dimeric) as the prototype ricin holotoxin from Ricinus communis that is composed of a catalytic active A chain linked via a disulphide bridge to a B-lectin domain that mediates efficient endocytosis in eukaryotic cells. Plant RIPs can recognize a universally conserved stem-loop, known as the α-sarcin/ ricin loop or SRL structure in 23S/25S/28S rRNA. By depurinating a single adenine (A4324 in 28S rat rRNA), they can irreversibly arrest protein translation and trigger cell death in the intoxicated mammalian cell. Besides their useful application as potential weapons against infected/tumor cells, ricin was also used in bio-terroristic attacks and, as such, constitutes a major concern. In this review, we aim to summarize past studies and more recent progresses made studying plant RIPs and discuss successful approaches that might help overcoming some of the bottlenecks encountered during the development of their biomedical applications.

Biological Effects and Clinical Applications of Dwarf Elder ( Sambucus ebulus L): A Review

Dwarf elder ( Sambucus ebulus L) is one of the best known medicinal herbs since ancient times. In view of its benefits as a widely applicable phytomedicine, it is still used in folk medicine of different parts of the world. In addition to its nutritional values, dwarf elder contains different phytochemicals among which flavonoids and lectins are responsible for most of its therapeutic effects. Dwarf elder has been used for different ailments including: joint pains, cold, wounds, and infections. Nevertheless, recent evidence has revealed its potentials for making attempts at treating cancer and metabolic disorders. This review aimed to provide a comprehensive description of dwarf elder regarding its traditional uses and modern findings which may contribute to the development of novel natural-based therapeutic agents.

Lectin Digestibility and Stability of Elderberry Antioxidants to Heat Treatment In Vitro

Elderberry contains healthy low molecular weight nutraceuticals and lectins which are sequence-related to the elderberry allergen Sam n1. Some of these lectins are type II ribosome-inactivating proteins. The sensitivity of native lectins present in elderberry fruits and bark to the proteolysis triggered by in vitro simulated gastric and duodenal fluids has been investigated. It was found that these lectins are refractory to proteolysis. Nonetheless, incubation for 5-10 min in a boiling water bath completely sensitized them to the hydrolytic enzymes in vitro. Under these conditions neither total Folin-Ciocalteau's reagent reactive compounds, total anthocyanins and the mixture of cyanidin-3-glucoside plus cyanidin-3-sambubioside, nor antioxidant and free-radical scavenging activities were affected by more than 10% for incubations of up to 20 min. Therefore, short-time heat treatment reduces potential allergy-related risks deriving from elderberry consumption without seriously affecting its properties as an antioxidant and free-radical scavenging food.

Oxidative damage induced by retching; antiemetic and neuroprotective role of Sambucus ebulus L

Nausea and vomiting are the most common symptoms in different diseases. Medicinal plants are considered as a reliable source of new drugs to control these symptoms. In this study, we evaluated the antiemetic and neuroprotective effects of the methanolic extract of Sambucus ebulus L. fruit and relationship between emesis (retching) and oxidative stress biomarkers in the mitochondria brain of young chickens. Emesis was induced by ipecac and copper sulphate (60 and 600 mg/kg, orally), respectively, and the methanolic extracts (50, 100, 200 mg/kg) were injected intraperitoneally (i.p.). The extract showed a significant antiemetic activity against ipecac and copper sulphate-induced emesis at all doses (p<0.001; percentages of retching inhibition 46, 96.5 and 83% against ipecac and 73, 79.5 and 69.2% against copper sulphate, respectively). Lipid peroxidation (LPO) was significantly decreased (p<0.001) at all doses of extract in retching induced by copper sulphate, and catalase (CAT) activity significantly increased (p<0.05) in the extract (50 mg/kg) and metoclopromide groups in retching induced by ipecac in the chickens' brain mitochondria. Protein carbonyl (PC) contents significantly (p<0.05) decreased only in extract (100 mg/kg) group in retching induced by ipecac. Mitochondria function (MTT assay) significantly increased by extract (100 mg/kg) as compared to control group in retching induced by ipecac. The results of this study suggests that the extract has protective effects, possibly by central and peripheral mechanisms, and neuroprotective effect by increasing plasma antioxidants or scavenging of free radicals induced by retching. It seems that extract could prevent protein modification and improve oxidative stress in the early stages.

A new age for biomedical applications of Ribosome Inactivating Proteins (RIPs): from bioconjugate to nanoconstructs

Ribosome-inactivating proteins (RIPs) are enzymes (3.2.2.22) that possess N-glycosilase activity that irreversibly inhibits protein synthesis. RIPs have been found in plants, fungi, algae, and bacteria; their biological role is still under investigation, even if it has been recognized their role in plant defence against predators and viruses. Nevertheless, several studies on these toxins have been performed to evaluate their applicability in the biomedical field making RIPs selectively toxic towards target cells. Indeed, these molecules are extensively used to produce chimeric biomolecules, such as immunotoxins or protein/peptides conjugates. However, to date, clinical use of most of these bioconiujates has been limited by toxicity and immunogenicity. More recently, material sciences have provided a wide range of nanomaterials to be used as excellent vehicles for toxin-delivery, since they are characterized by improved stability, solubility, and in vivo pharmacokinetics. This review discusses progresses in the development of RIPs bioconjugates, with particular attention to the recent use of nanomaterials, whose appropriate design opens up a broad range of different possibilities to the use of RIPs in novel therapeutic approaches in human diseases.

Shiga toxins: from structure and mechanism to applications

Shiga toxins are a group of type 2 ribosome-inactivating proteins (RIPs) produced in several types of bacteria. The toxins possess an AB5 structure, which comprises a catalytic A chain with N-glycosidase activity, and five identical B chains and recognize and bind to the target cells with specific carbohydrate moieties. In humans, the major molecular target which recognizes the Shiga toxins is the Gb3 receptor, which is mainly expressed on the cell surface of endothelial cells of the intestine, kidney, and the brain. This causes these organs to be susceptible to the toxicity of Shiga toxins. When a person is infected by Shiga toxin-producing bacteria, the toxin is produced in the gut, translocated to the circulatory system, and carried to the target cells. Toxicity of the toxin causes inflammatory responses and severe cell damages in the intestine, kidneys, and brain, bringing about the hemolytic uremic syndrome (HUS), which can be fatal. The Shiga toxin requires a couple of steps to exert its toxicity to the target cells. After binding with the target cell surface receptor, the toxin requires a complicated process to be transported into the cytosol of the cell before it can approach the ribosomes. The mechanisms for the interactions of the toxin with the cells are described in this review. The consequences of the toxin on the cells are also discussed. It gives an overview of the steps for the toxin to be produced and transported, expression of catalytic activity, and the effects of the toxin on the target cells, as well as effects on the human body.