Green tea polyphenols mitigate the plant lectins-induced liver inflammation and immunological reaction in C57BL/6 mice via NLRP3 and Nrf2 signaling pathways.

Plant-derived dietary lectins have been reported to be involved in the pathogenesis of several inflammatory diseases, including hepatitis, inflammatory bowel disease, diabetes, and celiac disease. In this present study, we aimed to assess whether green tea polyphenols (GTPs) exerts protective effects against plant lectins-induced liver inflammation and immunological reaction in mice. The C57BL/6 mice received intragastric GTPs (200 mg/kg b.w.) once per day for 7 consecutive days prior to plant lectins stimulation (50 mg/kg b.w., intraperitoneally). GTPs supplementation alleviated the histopathological changes of liver and the disorder of serum biochemical parameters in plant lectins-challenged mice. GTPs supplementation also alleviated plant lectins-induced oxidative stress and liver inflammation, decreasing protein contents and gene expression levels of pro-inflammatory cytokines in the plasma and hepatic tissue and increasing antioxidant capacity in the liver. GTPs decreased the protein expression levels of myeloperoxidase, F4/80 and neutrophil, as determined by immunohistochemical analysis, and T lymphocytes (CD4 and CD8) contents as determined by immunofluorescence analysis, in the liver. Moreover, we found that GTPs inhibited Nod-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome expression and increased nuclear factor erythroid 2-related factor 2 (Nrf2) pathways in the liver tissues of plant lectins-challenged mice. Taken together, these results show that GTPs alleviates hepatic inflammatory damage and immunological reaction after plant lectins challenge, and GTPs (or green tea intake) supplements can be beneficial for people exposed to plant lectins.

Moringa oleifera seed lectin inhibits Ehrlich ascites carcinoma cell growth by inducing apoptosis through the regulation of Bak and NF-κB gene expression.

A Moringa oleifera seed lectin (MOSL) was purified by using chitin column with the molecular mass of 17±1kDa. The lectin agglutinated mouse, cow and human erythrocytes and the hemagglutination activity was inhibited by methyl-α-d-mannopyranoside, methyl-ß-d-galactopyranoside, lactose and glucose. The lectin exhibited 100% hemagglutination activity at the pH range from 8.0 to 9.0 and temperature range from 30 to 60°C. Additionally, the lectin gradually lost its activity in the presence of urea but the activity abolish completely when treated with EDTA. MOSL showed mild toxicity against brine shrimp nauplii with a LC50 value of 131.0µg/ml. Antiproliferative activity was studied against Ehrlich ascites carcinoma (EAC) cells and 71.08% cell growth inhibition was observed in vitro at 200µg/ml. The lectin was injected (i.p.) into EAC mice at the doses of 2.0 and 4.0mg/kg/day for five consecutive days and 25.38% and 55% of cell growth inhibition was observed, respectively. MOSL caused the cell cycle arrest at G2/M phase as determined by FACS flow cytometry. The cell growth inhibition was due to the induction of apoptosis in the EAC cells which was confirmed by cell morphological study, caspase-3 inhibitor and activation of Bak and suppression of Bcl-2 and NF-κB genes expression.

Schinus terebinthifolius Leaf Extract Causes Midgut Damage, Interfering with Survival and Development of Aedes aegypti Larvae.

In this study, a leaf extract from Schinus terebinthifolius was evaluated for effects on survival, development, and midgut of A. aegypti fourth instar larvae (L4), as well as for toxic effect on Artemia salina. Leaf extract was obtained using 0.15 M NaCl and evaluated for phytochemical composition and lectin activity. Early L4 larvae were incubated with the extract (0.3-1.35%, w/v) for 8 days, in presence or absence of food. Polymeric proanthocyanidins, hydrolysable tannins, heterosid and aglycone flavonoids, cinnamic acid derivatives, traces of steroids, and lectin activity were detected in the extract, which killed the larvae at an LC50 of 0.62% (unfed larvae) and 1.03% (fed larvae). Further, the larvae incubated with the extract reacted by eliminating the gut content. No larvae reached the pupal stage in treatments at concentrations between 0.5% and 1.35%, while in the control (fed larvae), 61.7% of individuals emerged as adults. The extract (1.0%) promoted intense disorganization of larval midgut epithelium, including deformation and hypertrophy of cells, disruption of microvilli, and vacuolization of cytoplasms, affecting digestive, enteroendocrine, regenerative, and proliferating cells. In addition, cells with fragmented DNA were observed. Separation of extract components by solid phase extraction revealed that cinnamic acid derivatives and flavonoids are involved in larvicidal effect of the extract, being the first most efficient in a short time after larvae treatment. The lectin present in the extract was isolated, but did not show deleterious effects on larvae. The extract and cinnamic acid derivatives were toxic to A. salina nauplii, while the flavonoids showed low toxicity. S. terebinthifolius leaf extract caused damage to the midgut of A. aegypti larvae, interfering with survival and development. The larvicidal effect of the extract can be attributed to cinnamic acid derivatives and flavonoids. The data obtained using A. salina indicates that caution should be used when employing this extract as a larvicidal agent.

[Antagonistic effect of gingerols against TNF-α release, ROS overproduction and RIP3 expression increase induced by lectin from Pinellia ternata].

To explore the antagonistic effect of gingerols against the inflammation induced by lectin from Pinellia ternata. In this study, ELISA method was used to determine the effect of different extracts from gingerols on the release of inflammatory factor TNF-α from macrophages induced by lectin from P. ternata. The fluorescence probe was used to determine the effect of gingerols on the changes in ROS of macrophages induced by lectin from P. ternata. The western-blot method was applied to study the effect of gingerols on the increase in expression of cell receptor interacting protein RIP3 in macrophages induced by lectin from P. ternata. The scanning electron microscope (SEM) was used to study the effect of gingerols on morphological changes in macrophages induced by lectin from P. ternata. According to the results, gingerols can significantly inhibit the release of inflammatory factor from macrophages induced by lectin from P. ternata, ROS overproduction and increase in RIP3 expression. SEM results showed that gingerols can inhibit the cytomorphosis and necrocytosis induced by lectin from P. ternata. Fresh ginger's detoxication may be related to gingerols' effects in inhibiing release of inflammatory factor, ROS overproduction and increase in RIP3 expression caused by macrophages induced by lectin from P. ternata, which are mainly inflammatory development.

Molecular switch role of Akt in Polygonatum odoratum lectin-induced apoptosis and autophagy in human non-small cell lung cancer A549 cells.

Polygonatum odoratum lectin (POL), isolated from traditional Chinese medicine herb (Mill.) Druce, has drawn rising attention due to its wide biological activities. In the present study, anti-tumor effects, including apoptosis- and autophagy-inducing properties of POL, were determined by a series of cell biology methods such as MTT, cellular morphology observation, flow cytometry, immunoblotting. Herein, we found that POL could simultaneously induce apoptosis and autophagy in human non-small cell lung cancer A549 cells. POL initiated apoptosis through inhibiting Akt-NF-κB pathway, while POL triggered autophagy via suppressing Akt-mTOR pathway, suggesting the molecular switch role of Akt in regulating between POL-induced apoptosis and autophagy. Moreover, ROS was involved in POL-induced inhibition of Akt expression, and might therefore mediate both apoptosis and autophagy in A549 cells. In addition, POL displayed no significant cytotoxicity toward normal human embryonic lung fibroblast HELF cells. Due to the anti-tumor activities, POL might become a potent anti-cancer drug in future therapy, which might pave the way for exploring GNA-related lectins into effective drugs in cancer treatment.

Genotoxicity evaluation of Moringa oleifera seed extract and lectin.

UNLABELLED: This article reports the genotoxicity assessment of an extract of M. oleifera seed powder and the water-soluble Moringa oleifera lectin (WSMoL) isolated from seeds. The lectin isolated by chitin chromatography showed hemagglutinating activity with different erythrocytes, activity in a broad pH range (4.5 to 9.5), and retention of hemagglutinating activity after being heated to 100 °C. Genotoxicity of the seed extract and WSMoL were assessed using the cell-free plasmid DNA as well as the Salmonella typhimurium (Ames and Kado) assays with TA97, TA98, TA100, and TA102 in the presence or absence of hepatic metabolization. Seed extract at concentration (0.2 µg/µL) recommended to treat water was not genotoxic by Ames, Kado, and cell-free plasmid DNA assays. S. typhimurium strains showed to be sensitive to M. oleifera extract revealing a mutagenic effect at doses higher than 0.6 µg/µL with hepatic metabolization. The extract at doses higher than 0.4 µg/µL, without hepatic metabolization, was mutagenic for TA100 and TA102. WSMoL was nonmutagenic by used assays. The use of high concentrations of the extract may pose a risk to human health and the safe use of M. oleifera seed powder to treat water for human consumption requires more study; however, the purified lectin could be an alternative for water treatment. PRACTICAL APPLICATION: The concentration 0.2 µg/µL of M. oleifera seed extract recommended to treat water for humans did not pose a risk to human health. The mutagenicity detected at concentrations higher than 0.4 µg/µL was not due to WSMoL, lectin isolated from extract.

Avaliação do potencial de mutagenicidade e toxicidade da lectina hipoglicemiante de folha de bauhinia monandra (pata-de-vaca) / Mutagenic and toxic potential assessment of the hypoglycemic lectinfrom bauhinia monandra leave (pata-de-vaca)

As plantas medicinais têm sido usadas desde a antiguidade no tratamento de diversas enfermidades humanas. As folhas de Bauhinia monandra são amplamente utilizadas no Brasil como fitoterápico no tratamento do Diabetes Mellitus. A partir das folhas de B. monandra, foi purificada uma lectina galactose-específica, denominada de BmoLL, que também apresentou uma importante capacidade hipoglicemiante. Seguindo as normas propostas pela Portaria nº 116, de 8 de agosto de 1996 do Ministério da Saúde do Brasil, o trabalho objetivou avaliar o potencial de mutagenicidade e toxicidade da BmoLL, mediante a utilização dos testes com cepas de Escherichia coli da linhagem CC104 (Teste de mutagênesedireta), com cepas de Salmonella typhimurium da linhagem TA (Teste de Kado), com plasmídeo pBCKS (Quebra de DNA plasmidial) e com enzima Exonuclease III (Detecção de sítios abásicos). Os resultados demonstraram que a lectina foi incapaz de aumentar a freqüência de mutação reversa das cepas de S. typhimurium, com e sem ativador metabólico.No entanto, uma diminuição significativa na frequência de mutação espontânea foi observada nas cepas de E. coli, especialmente na deficiente de reparo (CC104mutMmutY), sugerindo um potencial antioxidante da lectina. A BmoLL é incapaz de gerar danos genotóxicos e citotóxicos, com base nas concentrações testadas e nos ensaios realizados.

Medicinal plants have been used since ancient times to treat various human diseases.The leaves of Bauhinia monandra are widely used in Brazil as herbal remedies in the treatmentof Diabetes Mellitus. From the leaves of B. monandra, a galactose-specific lectin was purified,called BmoLL, which also showed a significant hypoglycemic capacity. In accordance with therules proposed by Brazil?s Ministry of Health Decree 116 of 08 August 1996, this study aimedat assessing the potential for toxicity and mutagenicity of BmoLL by means of using tests withEscherichia coli strain CC104 (Forward mutagenesis assay) with Salmonella typhimurium strain TA(Kado test), with plasmid pBCKS (Break occurrences in plasmid DNA) and enzyme exonucleaseIII (Search of abasic sites). Results demonstrated that lectin was unable to increase the frequencyof reverse mutation of strains of S. typhimurium, with and without metabolic activity. However,a significant decrease in the frequency of spontaneous mutation was observed in strains ofE. coli, especially in poor repair (CC104mutMmutY), suggesting an anti-oxidant potential of lectin.BmoLL is unable to generate genotoxic and cytotoxic damage, based on the concentrations andtests performed.

Induction of apoptosis by mistletoe lectin I and its subunits. No evidence for cytotoxic effects caused by isolated A- and B-chains.

Type II ribosome inactivating proteins (RIP II) are generally known to induce apoptosis in human cells by the inhibition of protein biosynthesis. Recent data from mistletoe RIP II proteins (eg. mistletoe lectin I; ML1) suggest an additional mode of apoptosis induction through the binding of their lectin part to certain cell surface receptors as is known for some human galectins. In order to clarify this possibility, we used highly sensitive flow cytometric apoptosis assays and mistletoe hololectin subunits of proven purity to show that neither human lymphocytes nor Molt-4 cells undergo apoptosis after treatment with isolated lectin-type B-chains. In contrast to earlier investigations, only the hololectin was able to induce apoptosis in these assays. We conclude that direct apoptosis induction by mistletoe lectins occurs only after uptake of the molecules into the cell due to the action of the ribosome inactivating A-chain.

[Mistletoe therapy from the pharmacologic perspective]. / Zukunft der misteltherapie aus pharmakologischer sicht.

Because of their cytostatic/apoptotic and immunomodulatory effects mistletoe extracts are often applied in tumour patients. Recent experimental data suggest that the mistletoe lectins Viscum album agglutinin (VAA)-I and -II are play an important role in the efficacy of mistletoe therapy. VAA-I and -II are members of the type-II ribosome-inactivating proteins. VAA-I has been shown to induce cytostatic effects in cultures of various eukaryotic cells in vitro. In 24-hour cultures of human peripheral lymphocytes, flow-cytometric investigations with propidium iodide (PI) in hypotonic buffer and quantitative assessment of DNA breaks with terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-digoxigenin nick end-labeling (TUNEL) assay were carried out; they revealed a dose-dependent VAA-I-induced apoptosis (lectin concentrations between 10 ng/ml and 1 microg/ml). In 24-hour cultures of peripheral blood mononuclear cells (PBMC), VAA-I in non-cytotoxic concentrations (1+/-10 ng/ml) induced mRNA expression and enhanced the secretion of proinflammatory cytokines. The stimulation of NK cells by VAA-I in vitro was enhanced in additive manner by the combination of VAA-I with IL-2 and IL-12. In culture of PBMC and bone marrow CD34+ cells coincubation of VAA-I with other haematopoietic growth factors induced a dose-dependent increase in clonogenic growth. In cancer patients the mechanisms of natural immunity, believed to be essential for their survival, are often significantly decreased. VAA-I and standardized mistletoe extracts are able to stimulate the cellular parameters of natural immunity with a bell-shaped curve of efficacy. Studies in animal models suggest that application of 0.5-3 ng/kg VAA-I twice a week is effective in sustaining the elevation of the number and activity of peripheral blood NK cells. These parameters often exhibit high intrinsic fluctuations, in healthy persons, however, blind crossover studies reveal an optimal lectin dose of about 0.5 and 1 ng/kg bw, suggesting a potential use of mistletoe preparations as a modulator of the natural immune system. Selective apoptotic effects of VAA-I may represent a novel approach for pharmacological manipulation of the balance between cell growth and programmed cell death. Appropriate combination of immunomodulatory and cytotoxic doses may open new clinical perspectives in the mistletoe therapy.

Lectins in drug delivery: a study of the acute local irritancy of the lectins from Solanum tuberosum and Helix pomatia.

Lectins are proteins or glycoproteins of non-immune origin capable of binding to one or more specific sugar residues. The potential for using lectins as a means of 'anchoring' a drug delivery system to the mucosal surfaces of the eye has been investigated in previous work, with the lectins from Solanum tuberosum and Helix pomatia showing particular promise. In this study the acute local dermal irritancy of these lectins, in terms of their potential to cause inflammation and tissue necrosis, was investigated. After an initial study in terminally anaesthetised animals (to ensure no gross toxicity was evident), five male New Zealand white rabbits from the same litter were briefly anaesthetised and Evans blue injected intravenously as a marker of inflammation. Sterile lectin solutions in normal saline at a range of concentrations from 50 to 500 microg ml(-1) were prepared and 50-microl volumes injected intradermally at 18 sites across a shaved area of each rabbit's back. The rabbits were then allowed to regain consciousness. There was no evidence of tissue necrosis, oedema or Evans blue infiltration with any of the lectin solutions administered. The rabbits did not display any signs of discomfort such as scratching or continued grooming throughout the experiment. Histological examination of the injection sites revealed little sign of any inflammation, such as heterophil migration, oedema or tissue damage. It was concluded that these lectins demonstrate minimal acute irritancy, and will, therefore, be taken forward for formulation and in vivo studies.

Cytotoxic effects of the components in heat-treated mistletoe (Viscum album).

Major cytotoxic components were fractionated from Korean mistletoe and the changes of their cytotoxic effects caused by heat treatment were investigated. The high cytotoxicity of isolated lectin I completely disappeared by heating for 30 min. The fractions of viscotoxins and alkaloids maintained their activities even after heating for 60 and 180 min, respectively. The alkaloid fraction was more cytotoxic to tumor MSV cells than to non-tumor A31 cells and the activity pattern was not changed by heat treatment. The possible contributions of alkaloids and viscotoxins to the activities of heat-treated mistletoe extracts such as tea or decoctions are discussed.

Mistletoe lectin dissociates into catalytic and binding subunits before translocation across the membrane to the cytoplasm.

Hybridomas producing monoclonal antibodies (mAbs) against the mistletoe lectin A-chain (MLA) were obtained to investigate the intracellular routing and translocation of ribosome-inactivating proteins. Anti-MLA mAb MNA5 did not bind the holotoxin but interacted with isolated MLA. This epitope was not recognized upon MLA denaturation or conjugation of MLA with the ricin binding subunit (RTB). Furthermore, the mAbs did not appreciably react with a panel of MLA synthetic octapeptides linked to the surface of polyethylene pins. A study of the cytotoxicity of mistletoe lectin, ricin, and chimeric toxin MLA/RTB for the hybridomas revealed that interchain disulfide bond reduction and subunit dissociation are required for cytotoxic activity of mistletoe lectin.

Isolation and characterization of biologically active lectin from Korean mistletoe, Viscum album var. Coloratum.

A mistletoe lectin was isolated from water extracts of Korean mistletoe, a subspecies of Viscum album, grown on Quercus mongolica using CM-Sepharose chromatography followed by an affinity chromatography on a concanavalin A-Sepharose column. The compound proved to be a mistletoe lectin II with D-galactose and N-acetyl-D-galactosamine specificity. Matrix-assisted laser desorption time-of-flight mass spectroscopy showed it to have an average molecular mass of 62.7 kDa and to consist of two subunits of 30.6 kDa and 32.5 kDa. It was a basic protein with isoelectric points of 9.4 and 9.6 by capillary isoelectric focusing and was cytotoxic to Molt4 cell.

Primary structure and molecular modeling of mistletoe lectin I from Viscum album.

The first three-dimensional structure of the ribosome inactivating protein mistletoe lectin I (ML-I) from Viscum album has been modeled on the basis of the X-ray structure of castor bean ricin from Ricinus communis. The relative high sequence homology and conserved secondary structure enabled accurate modeling. The 196 sequence changes between ML-I and ricin could be accomodated with only little pertubation in the main chain folding. A close comparison of the primary structures of ML-I and ricin is given and the effects of the sequence changes are elucidated on the basis of the modeled three-dimensional structure. Differences have been identified in the vicinity of the active site, in the high affinity galactose binding site and in the interface between the A and B chains, which might account for the reduced cytotoxicity of ML-I.