Lectins isolated from Korean mistletoe (Viscum album coloratum) induce apoptosis in tumor cells

Multifunctional Cell Regulation Activities of the Mussel Lectin SeviL: Induction of Macrophage Polarization toward the M1 Functional Phenotype

SeviL, a galactoside-binding lectin previously isolated from the mussel Mytilisepta virgata, was demonstrated to trigger apoptosis in HeLa ovarian cancer cells. Here, we show that this lectin can promote the polarization of macrophage cell lines toward an M1 functional phenotype at low concentrations. The administration of SeviL to monocyte and basophil cell lines reduced their growth in a dose-dependent manner. However, low lectin concentrations induced proliferation in the RAW264.7 macrophage cell line, which was supported by the significant up-regulation of TOM22, a component of the mitochondrial outer membrane. Furthermore, the morphology of lectin-treated macrophage cells markedly changed, shifting from a spherical to an elongated shape. The ability of SeviL to induce the polarization of RAW264.7 cells to M1 macrophages at low concentrations is supported by the secretion of proinflammatory cytokines and chemokines, as well as by the enhancement in the expression of IL-6- and TNF-α-encoding mRNAs, both of which encode inflammatory molecular markers. Moreover, we also observed a number of accessory molecular alterations, such as the activation of MAP kinases and the JAK/STAT pathway and the phosphorylation of platelet-derived growth factor receptor-α, which altogether support the functional reprogramming of RAW264.7 following SeviL treatment. These results indicate that this mussel β-trefoil lectin has a concentration-dependent multifunctional role in regulating cell proliferation, phenotype, and death in macrophages, suggesting its possible involvement in regulating hemocyte activity in vivo.

Glycosylated SARs Cov 2 interaction with plant lectins

Lectins are non-immune carbohydrate-binding proteins/glycoproteins that are found everywhere in nature, from bacteria to human cells. They have also been a valuable biological tool for the purification and subsequent characterisation of glycoproteins due to their carbohydrate binding recognition capacity. Antinociceptive, antiulcer, anti-inflammatory activities and immune modulatory properties have been discovered in several plant lectins, with these qualities varying depending on the lectin carbohydrate-binding site. The Coronavirus of 2019 (COVID-19) is a respiratory disease that has swept the globe, killing millions and infecting millions more. Despite the availability of COVID-19 vaccinations and the vaccination of a huge portion of the world's population, viral infection rates continue to rise, causing major concern. Part of the reason for the vaccine's ineffectiveness has been attributed to repeated mutations in the virus's epitope determinant elements. The surface of the Coronavirus envelope is heavily glycosylated, with approximately sixty N-linked oligomannose, composite, and hybrid glycans covering the core of Man3GlcNAc2Asn. Some O-linked glycans have also been discovered. Many of these glyco-chains have also been subjected to multiple mutations, with only a few remaining conserved. As a result, numerous plant lectins with specificity for these viral envelope sugars have been discovered to interact preferentially with them and are being investigated as a potential future tool to combat coronaviruses such as the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by preventing viral attachment to the host. The review will discuss the possible applications of plant lectins as anti-coronaviruses including SARS-CoV-2, antinociceptive, anti-inflammation and its immune modulating effect.

The Genus Eranthis: Prospects of Research on Its Phytochemistry, Pharmacology, and Biotechnology

This review summarizes information about the chemical composition and beneficial properties of species of the genus Eranthis Salisb. from the world's flora. To date, seven out of ~14 species found in Asia and parts of Europe have been studied to various degrees. Here, data are presented on the diversity of sets of chromones, furochromones, triterpene saponins, coumarins, and other classes of secondary metabolites of Eranthis species according to the literature. For new compounds-isolated from Eranthis for the first time-structural formulas are also provided. Among the new compounds, chromones and coumarins predominate, as do triterpene saponins of the olean and cycloartane series and lectin. The results of pharmacological studies are presented showing anti-inflammatory, antioxidant, antiviral, and other types of biological activities found in extracts, in their fractions, and in individual compounds of the aboveground and underground organs and parts of Eranthis species. Despite the limited geographic range of Eranthis plants, it is possible to search for active substances, develop methods for biological and chemical synthesis of the isolated substances, and create a finished therapeutic substance based on them. In addition, it is feasible to obtain the desired standardized pure materials from Eranthis species grown in vitro.

A Comprehensive Review on Pharmacological Activities of Pachypodol: A Bioactive Compound of an Aromatic Medicinal Plant Pogostemon Cablin Benth

As is well known, plant products have been increasingly utilized in the pharmaceutical industry in recent years. By combining conventional techniques and modern methodology, the future of phytomedicines appears promising. Pogostemon Cablin (patchouli) is an important herb used frequently in the fragrance industries and has various therapeutic benefits. Traditional medicine has long used the essential oil of patchouli (P. cablin) as a flavoring agent recognized by the FDA. This is a gold mine for battling pathogens in China and India. In recent years, this plant has seen a significant surge in use, and approximately 90% of the world's patchouli oil is produced by Indonesia. In traditional therapies, it is used for the treatment of colds, fever, vomiting, headaches, and stomachaches. Patchouli oil is used in curing many diseases and in aromatherapy to treat depression and stress, soothe nerves, regulate appetite, and enhance sexual attraction. More than 140 substances, including alcohols, terpenoids, flavonoids, organic acids, phytosterols, lignins, aldehydes, alkaloids, and glycosides, have been identified in P. cablin. Pachypodol (C18H16O7) is an important bioactive compound found in P. cablin. Pachypodol (C18H16O7) and many other biologically essential chemicals have been separated from the leaves of P. cablin and many other medicinally significant plants using repeated column chromatography on silica gel. Pachypodol's bioactive potential has been shown by a variety of assays and methodologies. It has been found to have a number of biological activities, including anti-inflammatory, antioxidant, anti-mutagenic, antimicrobial, antidepressant, anticancer, antiemetic, antiviral, and cytotoxic ones. The current study, which is based on the currently available scientific literature, intends to close the knowledge gap regarding the pharmacological effects of patchouli essential oil and pachypodol, a key bioactive molecule found in this plant.

Structure-function and application of plant lectins in disease biology and immunity

Lectins are proteins with a high degree of stereospecificity to recognize various sugar structures and form reversible linkages upon interaction with glyco-conjugate complexes. These are abundantly found in plants, animals and many other species and are known to agglutinate various blood groups of erythrocytes. Further, due to the unique carbohydrate recognition property, lectins have been extensively used in many biological functions that make use of protein-carbohydrate recognition like detection, isolation and characterization of glycoconjugates, histochemistry of cells and tissues, tumor cell recognition and many more. In this review, we have summarized the immunomodulatory effects of plant lectins and their effects against diseases, including antimicrobial action. We found that many plant lectins mediate its microbicidal activity by triggering host immune responses that result in the release of several cytokines followed by activation of effector mechanism. Moreover, certain lectins also enhance the phagocytic activity of macrophages during microbial infections. Lectins along with heat killed microbes can act as vaccine to provide long term protection from deadly microbes. Hence, lectin based therapy can be used as a better substitute to fight microbial diseases efficiently in future.

The response of fish to immunostimulant diets

In order to maintain fish health and to improve performance immunostimulants have been used as dietary additives to improve weight gain, feed efficiency, and/or disease resistance in cultured fish. In aquaculture, non-specific immunostimulants have been widely used probably due to the limited knowledge of the immune response in fish and the ease of their application. Many studies have been carried out to assess the effect of dietary immunostimulants in fish including algal derivatives, herb and plant extract containing diets using a wide range of downstream analytical techniques. Many immunostimulants are based upon tradition and folklore transferred through generations and specific to certain geographical regions rather than known biological properties. However, there are studies in which it is possible to observe a clear and direct dose-dependent stimulatory effect upon the immune system. Other dietary supplements used contain PAMPs (Pathogen Associated Molecular Patterns) as immunostimulants whose recognition depends upon PRR (pathogen recognition receptor) interactions including the TLRs (Toll-like receptor). Despite the growing interest in the use of immunostimulants across the aquaculture industry the underlying mechanisms of ligand recognition, extract composition and activation of the fish immune response remains fragmented. In this review we focus upon the last 15 years of studies addressing the assessment of: (1) plant, herb and algae extracts; and (2) PAMPs, upon non-specific immune parameters of activation and immunostimulant diet efficacy.

Solid-phase extraction based on ground methacrylate monolith modified with gold nanoparticles for isolation of proteins

In this study, a novel polymeric material functionalized with gold nanoparticles (AuNPs) was prepared as solid-phase extraction (SPE) sorbent for isolation of proteins. The sorbent was synthesized from a powdered poly(glycidyl-co-ethylene dimethacrylate) monolith, and modified with ammonia, followed by immobilization of AuNPs on the pore surface of the material. To evaluate the performance of this SPE support, proteins were selected as test solutes, being the extraction conditions and other parameters (loading capacity and regenerative ability of sorbent) established. The results indicated that this sorbent could be employed to selectively capture proteins according to their pI, on the basis of the strong affinity of these biomacromolecules towards to AuNPs surface. The applicability of this sorbent was demonstrated by isolating protein species of interest (bovine serum albumin, cytochrome c and lectins in European mistletoe leaves), followed by SDS-PAGE analysis.

European Viscum album: a potent phytotherapeutic agent with multifarious phytochemicals, pharmacological properties and clinical evidence

Viscum albumL. or European mistletoe (Loranthaceae), a semi-parasitic shrub, has been used as a traditional medicine in Europe for centuries to treat various diseases like cancer, cardiovascular disorder, epilepsy, infertility, hypertension and arthritis.

Ribosome-inactivating and related proteins

Ribosome-inactivating proteins (RIPs) are toxins that act as N-glycosidases (EC 3.2.2.22). They are mainly produced by plants and classified as type 1 RIPs and type 2 RIPs. There are also RIPs and RIP related proteins that cannot be grouped into the classical type 1 and type 2 RIPs because of their different sizes, structures or functions. In addition, there is still not a uniform nomenclature or classification existing for RIPs. In this review, we give the current status of all known plant RIPs and we make a suggestion about how to unify those RIPs and RIP related proteins that cannot be classified as type 1 or type 2 RIPs.

Preclinical and clinical effects of mistletoe against breast cancer

Breast cancer is among the most frequent types of cancer in women worldwide. Current conventional treatment options are accompanied by side effects. Mistletoe is amongst the important herbal medicines traditionally used as complementary remedies. An increasing number of studies have reported anticancer activity of mistletoe extracts on breast cancer cells and animal models. Some recent evidence suggests that cytotoxic activity of mistletoe may be mediated through different mechanisms. These findings provide a good base for clinical trials. Various studies on mistletoe therapy for breast cancer patients revealed similar findings concerning possible benefits on survival time, health-related quality of life (HRQoL), remission rate, and alleviating adverse reactions to conventional therapy. This review provides an overview of the recent findings on preclinical experiments and clinical trials of mistletoe for its cytotoxic and antitumor activity and its effect on HRQoL in breast cancer patients. Moreover, studies investigating molecular and cellular mechanisms underlying antitumor activity of mistletoe are discussed in this paper. The analyzed trials provided evidence that there might be a combination of pharmacological and motivational aspects mediated by the mistletoe extract application which may contribute to the clinical benefit and positive outcome such as improved HRQoL and self-regulation in breast cancer patients.

Synergistic anticancer effects of lectin and doxorubicin in breast cancer cells

We studied the effects, either combined or alone, of lectin from Korean mistletoe (Viscum album var. coloratum agglutinin, VCA) and doxorubicin (DOX) in MCF-7 (estrogen receptor-positive) and MDA-MB231 (estrogen receptor-negative) human breast cancer cells. When VCA and DOX were combined, a strong synergistic effect was shown in cell growth inhibition, compared to VCA or DOX treatment alone. In quantitative apoptosis studies analyzed by flow cytometry, a combination of two agents showed an increase in apoptosis in both cells, compared to agents alone. Also, pro-apoptotic proteins including Bax, Bik, and Puma were increased in both cells, and the survival factor Bcl-2 was inhibited in MCF-7 cells when drugs were combined. Furthermore, VCA combined with DOX mediated S phase arrest, accompanied with a decrease of cell number at G0/G1 phase. This suggests that VCA and DOX combination may possibly lead to a novel strategy for the treatment of breast cancer.

Enhanced dendritic cell maturation by the B-chain of Korean mistletoe lectin (KML-B), a novel TLR4 agonist

Korean mistletoe lectin (KML) is composed of A and B sub-chains. The B-chain binds to cell surfaces, whereas the A-chain hinders translation because it is a RIP (ribosome inactivating protein) inducing apoptosis. Although KML has various biological and immunological activities, its potential use in cancer therapy or as an adjuvant therapy is limited by its toxicity to normal cells. This study was conducted to determine whether the B-chain of KML (KML-B) has immunoadjuvant activity and cytotoxicity activity. To evaluate the immunomodulatory activities of B chain KML, in vitro experiments employing bone marrow-derived dendritic cells (BMDCs) were performed. Dendritic cells (DCs) are a unique group of white blood cells that are able to capture and process antigens for presentation to T cells, which constitute primary immune response. In the present study, KML-B was found to be non-cytotoxic to BMDCs. Furthermore, the expressions of co-stimulatory molecules (CD40, CD80, CD86, and MHC II) and the secretions of cytokines (IL-1β, IL-6, IL-12p70, and TNF-α) were increased in BMDCs by KML-B. In addition, other indicators (antigen-uptake and CCR7 expression) of BMDC maturation were changed by KML-B, and the ability of KML-B to enhance various functions by BMDCs was found to be dependent on TLR4 expression. Moreover, BMDCs matured by KML-B induced naïve CD4(+) T cell differentiation toward Th1 cells directly and indirectly. These experiments confirm that KML-B exhibits potent immunomodulatory properties and suggest that KML-B be considered a potential dendritic cell-based cancer therapy and immunoadjuvant.

Protein Fractions from Korean Mistletoe (Viscum Album coloratum) Extract Induce Insulin Secretion from Pancreatic Beta Cells

Mistletoe (Viscum Album coloratum) has been known as a medicinal plant in European and Asian countries. Recent data show that biological activity of mistletoe alleviates hypertension, heart disease, renal failure, and cancer development. In this study, we report the antidiabetic effect of Korean mistletoe extract (KME). KME treatments enhanced the insulin secretion from the pancreatic β-cell without any effects of cytotoxicity. PDX-1 and beta2/neuroD known as transcription factors that regulate the expression of insulin gene were upregulated by treatment of the KME protein fractions isolated by ion-exchange chromatography after ammonium sulfate precipitation. Furthermore, these KME protein fractions significantly lowered the blood glucose level and the volume of drinking water in alloxan induced hyperglycemic mice. Taken together with the findings, it provides new insight that KME might be served as a useful source for the development of medicinal reagent to reduce blood glucose level of type I diabetic patients.

The immunomodulatory effect of plant lectins: a review with emphasis on ArtinM properties

Advances in the glycobiology and immunology fields have provided many insights into the role of carbohydrate-protein interactions in the immune system. We aim to present a comprehensive review of the effects that some plant lectins exert as immunomodulatory agents, showing that they are able to positively modify the immune response to certain pathological conditions, such as cancer and infections. The present review comprises four main themes: (1) an overview of plant lectins that exert immunomodulatory effects and the mechanisms accounting for these activities; (2) general characteristics of the immunomodulatory lectin ArtinM from the seeds of Artocarpus heterophyllus; (3) activation of innate immunity cells by ArtinM and consequent induction of Th1 immunity; (4) resistance conferred by ArtinM administration in infections with intracellular pathogens, such as Leishmania (Leishmania) major, Leishmania (Leishmania) amazonensis, and Paracoccidioides brasiliensis. We believe that this review will be a valuable resource for more studies in this relatively neglected area of research, which has the potential to reveal carbohydrate targets for novel prophylactic and therapeutic strategies.

TLR4-mediated activation of mouse macrophages by Korean mistletoe lectin-C (KML-C)

Korean mistletoe lectin (KML-C) is an adjuvant that activates systemic and mucosal immune cells to release cytokines including TNF-alpha, which induces immunity against viruses and cancer cells. Although the immunomodulatory activity of KML-C has been well established, the underlying mechanism of action of KML-C has yet to be explored. When mouse peritoneal macrophages were treated with KML-C, both transcription and translation of TLR4 were upregulated. KML-C-induced TLR4 downstream events were similar to those activated by LPS: the upregulation of interleukin-1 receptor-associated kinase-1 (IRAK1); resulting in macrophage activation and TNF-alpha production. When TLR4 was blocked using a TLR4-specific neutralizing antibody, TNF-alpha production from the macrophages was significantly inhibited. Moreover, TLR4-deficient mouse macrophages treated with KML-C also secreted greatly reduced level of TNF-alpha secretion. Finally, TLR4 molecules were co-precipitated with KML-C, to which agarose beads were conjugated, indicating that those molecules are associated. These data indicate that KML-C activates mouse macrophages to secrete TNF-alpha by interacting with the TLR4 molecule and activating its signaling pathways.

Immunomodulating effects of Korean mistletoe lectin in vitro and in vivo

The immunomodulatory effects of Korean mistletoe lectin (KML), one of the major active components in Viscum album L. var. coloratum, were investigated in vitro in immune cell proliferation and natural killer (NK) cell- and macrophage-mediated cytotoxicity, and in vivo in the forced swim test and cold stress. In mitogen-induced lymphocyte proliferation of murine splenocytes, concanavalin A and lipopolysaccharide significantly increased the proliferation of T cell and B cell lymphocytes, respectively. KML exposure increased lymphocyte proliferation in response to mitogen. KML also increased the splenic NK cell and macrophage activities in vitro. Exposure to KML increased production of cytokines such as interleukin-1 and interleukin-6 by macrophages. Two-week treatment with KML (30, 100, 300 and 600 microg/kg) increased the recruitment of lymphocytes, monocytes and macrophages. In the forced swim test, the immobility time was significantly attenuated by treatment with KML (300 and 600 microg/kg). In a cold stress experiment, spleen and thymus weight increased in KML-treated mice, while the weight of adrenal gland was lower than that in vehicle-treated mice. The levels of serum aminotransferases, lactate dehydrogenase and alkaline phosphatase were decreased by KML treatment. KML treatment also induced increases in the percentages of CD4(+) and CD8(+) cells in thymus. Our results suggest that KML enhances the immune system through modulation of lymphocytes, NK cells, and macrophages.

Antiproliferation and apoptosis of human tumor cell lines by a lectin (AMML) of Astragalus mongholicus

A lectin (AMML) from the roots of Astragalus mongholicus was extracted and purified by affinity chromatographic technique. Human cervical carcinoma cell line (HeLa), human osteoblast-like cell line (MG63) and human leukemia cell line (K562) were used to check the effects of AMML on cell proliferation, apoptosis and cell cycle. Maximum growth inhibition (92%) was observed with HeLa cells, followed by K562 cells (84%) and MG63 (48%) cells. Morphological observation showed that AMML-treated HeLa cells displayed outstanding apoptosis characteristics, such as nuclear fragmentation and appearance of membrane-enclosed apoptotic bodies. The apoptosis of HeLa cells was confirmed by flow cytometry using Annexin V/FITC and propidium iodide (PI) staining technique. For the first time we also report a significant cell cycle arrest at S phase of HeLa cells by AMML. Therefore, the present investigation may lead to the possible therapeutic use of Astragalus mongholicus lectin.

Plant lectins: potential antineoplastic drugs from bench to clinic

Plant lectins, carbohydrate-binding proteins distributed widely in a variety of plant species, have drawn a rising attention for cancer biologists due to their remarkable anti-tumour properties. In this review, we present a brief outline of the up-to-date advances of plant lectins in elucidating their complex anti-cancer mechanisms implicated in apoptosis and autophagy. In addition, we further discuss the pre-clinical and clinical studies of plant lectins for their potential therapeutic applications. In conclusion, these inspiring findings would open a new perspective for plant lectins as potential antineoplastic drugs from bench to clinic.

Toxicological studies of two compounds isolated from Loranthus globosus Roxb

The sub-acute toxicities of two compounds 3,4-dimethoxycinnamyl alcohol (1) and 3,4,5-trimethoxycinnamyl alcohol (2) isolated from the plant Loranthus globosus Roxb were studied on long Evan's rats. The studies included the gross general observation such as changes in body weight, haematological profiles [total count of Red Blood Cells (RBC) and White Blood Cells (WBC), differential count of WBC, platelet count and Haemoglobin (Hb)%], biochemical parameters of blood [Serum Glutamate Oxaloacetate Transaminase (SGOT), Serum Glutamate Pyruvate Transaminase (SGPT), Serum Alkaline Phosphatase (SALP), urea and creatinine) and histopathology of the liver, kidney, heart and lung of both control and experimental groups of rats. The changes in haematological and biochemical parameters were statistically not significant after the administration of compounds 1 and 2 in a dose of 300 microg/rat/day for consecutive 14 days. No abnormality was found in the histopathology of the liver, kidney, heart and lung in the experimental groups of rats following same dose when compared with control group. This preliminary study suggests that the isolated compounds may be used safely for clinical trial.

Growth inhibitory activity of a novel lectin from Cliona varians against K562 human erythroleukemia cells

PURPOSE

In this study, the antitumoral potential of a novel lectin (CvL) purified from the marine sponge Cliona varians was studied in different cancer cell lines.

METHODS

CvL cytotoxicity was evaluated in mammalian tumor cells and in normal human peripheral blood lymphocytes by the MTT assay using the same range of concentrations (1-150 microg ml(-1)). The mechanisms involved in K562 cell death were investigated by confocal fluorescence microscopy, flow cytometry and immunoblot.

RESULTS

CvL inhibited the growth of human leukemia cells, with IC(50) values of 70 and 100 microg ml(-1) for K562 and JURKAT cells, respectively, but it was ineffective on blood lymphocytes and solid tumor cell lines. K562 cell death occurred 72 h after exposure to the lectin and with signs of apoptosis, as analyzed by DAPI and annexin V/PI staining. Investigation of the possible mediators of this process showed that cell death occurred via a caspase-independent pathway. Confocal fluorescence microscopy indicated a pivotal role for the lysosomal protease cathepsin B in mediating cell death. Accordingly, pre-incubation of K562 cells with the cathepsin inhibitor L-trans-epoxysuccinyl-L-leucylamido-(4-guanidino)butane (E-64) abolished CvL cytotoxic effect. Furthermore, we found upregulation of tumor necrosis factor receptor 1 (TNFR1) and down-modulation of p65 subunit of nuclear factor kappa B (NFkappaB) expression in CvL-treated cells. These effects were accompanied by increased levels of p21 and reduced expression of pRb, suggesting that CvL can induce cell cycle arrest.

CONCLUSIONS

Collectively, these findings indicate an antileukemic effect for CvL and suggest that cathepsin B acts as a death mediator in CvL-induced cytotoxicity possibly in an uncharacterized connection with the membrane death receptor pathway.

Efficient intracellular delivery of functional proteins using cationic polymer core/shell nanoparticles

Cationic core/shell nanoparticles self-assembled from biodegradable, cationic and amphiphilic copolymer poly{N-methyldietheneamine sebacate)-co-[(cholesteryl oxocarbonylamido ethyl) methyl bis(ethylene) ammonium bromide] sebacate}, P(MDS-co-CES), were fabricated and employed to deliver lectin A-chain, an anticancer glycoprotein. Lectin A-chain was efficiently bound onto the surfaces of the nanoparticles at high mass ratios of nanoparticles to lectin A-chain. The nanoparticle/lectin A-chain complexes had an average size of approximately 150 nm with zeta potential of about +30 mV at the mass ratio of 50 or above while the BioPorter/lectin A-chain complexes had a larger particle size and relatively lower zeta potential (150 nm vs. 455 nm; +30 mV vs. +20 mV). Therefore, the cellular uptake of nanoparticle/lectin A-chain complexes was much greater than that of BioPorter/lectin A-chain complexes. The results obtained from cytotoxicity tests show that lectin A-chain delivered by the nanoparticles was significantly more toxic against MDA-MB-231, HeLa, HepG2 and 4T1 cell lines when compared to BioPorter, and IC50 of lectin A-chain delivered by the nanoparticles was 0.2, 0.5, 10 and 50 mg/l, respectively, while that of lectin A-chain delivered by BioPorter was higher than 100 mg/l in all cell lines tested. These nano-sized particles may provide an efficient approach for intracellular delivery of biologically active proteins.

Isolation and characterization of two Korean mistletoe lectins

Two isolectins (KML-IIU and the KML-IIL) were individually isolated from the previously reported Korean mistletoe lectin, KML-C, by using an immunoaffinity column. Molecular weights of the KML-IIU and the KML-IIL were 64 kDa and 60 kDa respectively. Both of the lectins were composed of heterogeneous A and B subunits linked with a disulfide bond, and showed the same carbohydrate-binding specificities for Gal and GalNAc. However, they are different not only in biophysical properties (glycosylation and amino acid compositions) but also bioactivities (cell killing and cytokine induction). The KML-IIL showed 17-145 times stronger in cytotoxicities to various human and mouse cancer cell lines than the KML-IIU. The KML-IIL also induced TNF-alpha secretion from mouse peritoneal macrophages 4.5 times better than the KML-IIU. The results demonstrated isolectins in Korean mistletoe were varied in bioactivities and the KML-IIL may be developed as an anti-cancer agent.

Low-dose mistletoe lectin-I reduces melanoma growth and spread in a scid mouse xenograft model

This study investigates the effects of mistletoe lectin-I (ML-I) on melanoma growth and spread in vivo. The human melanoma cell line MV3 was xenografted into severe combined immunodeficient mice and vehicle solution or purified ML-I was administered at 30, 150 and 500 ng per kg body weight (20 mice per group) daily. After 19 days, mice were killed, primary tumours (PTs) and lungs were dissected out, and tumour weights, number of lung metastases (LMs), number of tumour-infiltrating dendritic cells (DCs), and apoptosis rates in the melanoma cells and in the DCs were assessed. A 35% reduction of PT weight (P=0.03) and a 55% decrease in number of LMs (P=0.016) were evident for low-dose ML-I (30 ng kg(-1)) treatment but not for higher doses. Mistletoe lectin-I increased apoptosis rates in the melanoma cells of PTs at all doses, while no induction of apoptosis was noted in the LMs. Low-dose ML-I significantly increased the number of DCs infiltrating the PTs (P<0.0001) and protected DCs against apoptosis, while higher doses induced apoptosis in the DCs (P<0.01). Our results demonstrate that low-dose ML-I reduced melanoma growth and number of metastases in vivo, primarily due to immunomodulatory effects.

Dietary Korean mistletoe enhances cellular non-specific immune responses and survival of Japanese eel (Anguilla japonica)

The present study was performed to investigate the immunostimulatory effects of Korean mistletoe extract (KM-110; Viscum album Coloratum) on the non-specific immune response and protection against Aeromonas hydrophila infection in Japanese eel (Anguilla japonica). Eels were fed under 4 regimes, 0%, 0.1%, 0.5% and 1.0% KM-110 mixed diet. On day 14 after feeding, 15 fish from each group were injected i.p. with live A. hydrophila (3 x 10(6)CFU) and the remaining unchallenged fish from each group were used to study the innate immune response. On 14 days post-infection, the total survival rates were 26.6% in control, and 33.3%, 66.6% and 80% in 0.1%, 0.5% and 1% KM-110-treated groups, respectively. The maximum lysozyme activity was observed in the 1% KM-110-treated group. There was no significant difference of lysozyme activity between 0.1% and 0.5% KM-110 group. Superoxide anion (O(2)(-)) production was significantly (p<0.05) augmented in the 0.5% and 1% KM-110 groups compared to the control and 0.1% KM-110 group. No significant difference of (O(2)(-) production was found between 0.5% and 1% KM-110 group. Likewise, there was a significant increase in phagocytic activity in the 0.5% KM-110 group compared with the 0.1% group (p<0.05), but no significant difference between the 0.5% and the 1% KM-110 group indicating that 0.5% KM-110 concentration is suitable for stimulating maximum phagocytic activity resulting in a high amount of ROI production. Considering the present results, KM-110 could be utilized as a promising immunostimulating substance for a diet in aquaculture.

In vitro immunoregulatory effects of Korean mistletoe lectin on functional activation of monocytic and macrophage-like cells

Korean mistletoe lectin (KML) is one of the major active components in Viscum album var. (coloratum), displaying various biological effects such as anti-tumor and anti-metastatic activities. Even though it has been shown to boost host immune defense mechanisms, the immunomodulatory effects of KML on specific immune responses mediated by macrophages have not been fully elucidated. Therefore, in this study, we aimed to demonstrate KML's regulatory roles on macrophage-mediated immune responses. KML clearly blocked lipopolysaccharide (LPS)-induced events [expression of interleukin (IL)-10, nitric oxide (NO) production and phagocytic uptake], and suppressed the normal expression levels of IL-10 (at 2 ng/ml) and tumor necrosis factor (TNF)-alpha (at 10 ng/ml). In contrast, (1) the expression of cytokine (TNF-alpha) and (2) the generation of reactive oxygen species (ROS) induced by LPS were significantly up-regulated with KML co-treatment. In addition, KML itself increased the mRNA levels of IL-3 and IL-23; phagocytic uptake; the surface levels of co-stimulatory molecules (CD80 and CD86), pattern recognition receptors (PRRs) [such as dectin-1 and toll like receptor (TLR)-2] and adhesion molecules [beta1-integrins (CD29) and CD43]; and CD29-mediated cell adhesion events. Finally, according to co-treatment of D-galactose with KML under LPS-induced NO production conditions, KML inhibition seems to be mediated by binding to proteins with D-galactose. Therefore, these data suggest that KML may participate in regulating various macrophage-mediated innate and adaptive responses via binding to surface protein with D-galactose and that some of these may deserve in KML's therapeutic activities such as anti-tumor and anti-microbial effects.

Intranasal immunization with influenza virus and Korean mistletoe lectin C (KML-C) induces heterosubtypic immunity in mice

The mucosal adjuvanticity of Korean mistletoe lectin C (KML-C) was investigated in mice intranasally immunized with inactivated influenza virus (H1N1). Mucosal and systemic immune responses were compared to those induced with cholera toxin B subunit (CTB). KML-C increased influenza-specific antibodies with dominant IgG1 subclass in serum, IgG in genital secretions and IgA in saliva, and significantly enhanced influenza-specific lymphocyte proliferation and cytotoxic activity in spleens and in mediastinal lymph nodes. When KML-C was used as a mucosal adjuvant, mice were completely protected from mortality after the challenge with a homologous (H1N1) mouse-adapted influenza virus. After challenge with heterologous (H3N2) influenza virus the level of heterosubtypic immunity in KML-C-treated mice was comparable to that of mice that received CTB as adjuvant. These findings suggest that KML-C may be used as an effective mucosal adjuvant.

Mechanisms involved in Korean mistletoe lectin-induced apoptosis of cancer cells

AIM: To investigate the anti-cancer mechanisms of Korean mistletoe lectin (Viscum album coloratum agglutinin, VCA) using a human colon cancer cell line (COLO).

METHODS: Cytotoxic effects of VCA on COLO cells were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay in vitro and tumor-killing effects in vivo. To study the mechanisms involved, the expression of various pro-caspases, anti-apoptotic proteins, and death receptors was determined by western blot. To determine which death receptor is involved in VCA-induced apoptosis of COLO cells, cytotoxicity was examined by MTT assay after treatment with agonists or antagonists of death receptors.

RESULTS: VCA killed COLO cells in a time- and dose-dependent manner and induced complete regression of tumors in nude mice transplanted with COLO cells. Treatment of COLO cells with VCA activated caspase-2, -3, -8, and -9 and decreased expression of anti-apoptotic molecules including receptor interacting protein, nuclear factor-κB, X-linked inhibitor of apoptosis protein, and Akt/protein kinase B. We then examined the involvement of death receptors in VCA-induced apoptosis. Only tumor necrosis factor receptor 1, among the death receptors examined, was involved in apoptosis of COLO cells, evidenced by inhibition of VCA-induced apoptosis and decreased activation of caspases, particularly caspase-8, by tumor necrosis factor receptor 1 antagonizing antibody.

CONCLUSION: VCA-induced apoptotic COLO cell death is due to the activation of caspases and inhibition of anti-apoptotic proteins, in part through the tumor necrosis factor receptor 1 signaling pathway.

Mistletoe lectin (Viscum album coloratum) modulates proliferation and cytokine expressions in murine splenocytes

It is well documented that an extract of European mistletoe has a variety of biological effects, such as the stimulation of cytokine production from immune cells, and additional immunoadjuvant activities. While the European mistletoe has been studied intensively, we know less about Korean mistletoe as a therapeutic plant, especially as a possible immunomodulating drug. This study will investigated the effects of Korean mistletoe lectin (Viscum album L. var. coloratum agglutinin, VCA) on murine splenocytes to investigate whether VCA acts as an immunomodulator, which could lead to improved immune responses in these cells. The results showed that VCA inhibited cell proliferation at higher concentrations (at 1-8 ng/ml) and enhanced cell proliferation at lower concentrations (at 4-32 pg/ml). Further studies were carried out to determine if the proproliferative or anti-proliferative activity exhibited by VCA was correlated with cytokine secretion. Consequently, interferon (IFN)-gamma secretion was decreased in concanavalin A (ConA)-stimulated murine splenocytes by VCA (4-64 ng/ml), but there was no change in IL-4 levels. This suggests that VCA has the ability to modulate murine splenocyte proliferation and can possibly act on the balance of Th1/Th2 cellular immune responses.

Molecular Characterization of the Recombinant A-chain of a Type II Ribosome-Inactivating Protein (RIP) from Viscum album coloratum and Structural Basis on its Ribosome-Inactivating Activity and the Sugar-binding Properties of the B-chain

Mistletoe (Viscum album) lectins, which are classified as a type II ribosome-inactivating protein (RIP) due to their unique biological function and the potential medical and therapeutic application in cancer cells, receive a rising attention. The heterodimeric glycoproteins contain the Achain with catalytic activity and the B-chain with sugar binding properties. In recent years, studies involving the lectins from the white berry European mistletoe (Viscum album) and the yellow berry Korean mistletoe (Viscum album coloratum) have been described. However, the detailed mechanism in exerting unique cytotoxic effect on cancer cells still remains unclear. Here, we aim to understand and define the molecular basis and biological effects of the type II RIPs, through the studies of the recombinant Korean mistletoe lectin. To this end, we expressed, purified the recombinant Korean mistletoe lectin (rKML), and investigated its molecular characteristics in vitro, its cytotoxicity and ability to induce apoptotic cell death in cancer cells. To gain structural basis for its catalytic activity and sugar binding properties, we performed homology modeling studies based on the high degree of sequence identity and conserved secondary structure prediction between Korean and European, Himalayan mistletoe lectins, and Ricin.

Immunopotentiating effect of a Fomitella fraxinea-derived lectin on chicken immunity and resistance to coccidiosis

This study reports a novel immunopotentiating effect of a lectin (FFrL) extracted from the mushroom Fomitella fraxinea on poultry cell-mediated immunity and poultry coccidiosis. We describe the extraction of FFrL, its in vitro mitogenic activity and in vivo protection against an oral challenge infection with Eimeria acervulina. When tested on several cell types, crude FFrL agglutinated mouse erythrocytes and thymocytes and various other cells including murine and human cell lines. However, crude FFrL did not agglutinate human erythrocytes. Crude FFrL showed a potent mitogenic activity on chicken splenic lymphocytes, and at lower concentrations it exerted stronger mitogenic activity than Concanavalin A, a well-known potent mitogen for lymphocytes. Further, FFrL significantly induced (P < 0.05) nitric oxide secretion in HD11 cells and suppressed (P < 0.05) RP9 tumor cell growth in a dose-dependent fashion. When injected into 18-d-old chicken embryos followed by a posthatch oral E. acervulina challenge infection, FFrL treatment significantly protected chickens against weight loss associated with coccidiosis (P < 0.05). Injecting embryos with FFrL also resulted in significant reduction in oocyst shedding as compared with the control saline-injected birds (P < 0.05). The results of this study demonstrate that FFrL can be an effective growth promoting and immunostimulating agent in poultry during coccidiosis.

Influence of mistletoe lectins and cytokines induced by them on cell proliferation of human melanoma cells in vitro

Although aqueous mistletoe extracts are widely used in complementary cancer therapy, the precise mode of action of their main therapeutic agents, the three mistletoe lectins (MLs), is poorly understood as they act both as cytotoxic agents and as immunomodulators due to their cytokine release by mononuclear cells. Thus, this study aims to investigate both the direct and the indirect effects of MLs on the growth of human melanoma cells in vitro. Proliferation of six human melanoma cell lines under ML treatment and additionally under the influence of cytokines induced by them (TNF-alpha, IL-1, IL-6) was assessed by means of the tetrazolium derived reduction (XTT) assay. Furthermore, ML binding patterns were analysed and correlated with the biological effects. All three MLs inhibited melanoma cell proliferation in a dose-dependent manner starting at very low ML concentrations (0.001-100 ng/ml) with ML-I being the most cytotoxic lectin (significant inhibition of ultra-sensitive cell line MV3 at 1 x 10(-13) ng ML-I/ml). Even if applied in a broad concentration range (0.0001-100 ng/ml) cytokines had no influence on cell proliferation at all. For ML-I, no association between binding intensity and cytotoxicity was observed, while for ML-II and -III an association between binding and toxicity was established. In conclusion, this study emphasises the direct anti-proliferative effect of the mistletoe lectins on melanoma cells with ML-I being superior to MLs-II and -III. The observation of an ultra-sensitivity of one cell line towards ML-I toxicity may serve as an explanation for the therapeutic success in anecdotal case reports and needs further investigations.

Isolation ofepi-oleanolic acid from korean mistletoe and its apoptosis-lnducing activity in tumor cells

A triterpene was isolated as a cytotoxic principle from the dichloromethane extract of Korean mistletoe (KM; Viscum album coloratum) by repeated silica gel chromatography and recrystallization. In in vitro analysis of cytotoxic activity using various human and murine tumor cell lines, the dichloromethane extract of KM was highly cytotoxic against these cells. We isolated the most active compound, referred to VD-3, from the dichloromethane extract of KM. The VD-3 was shown to be less cytotoxic to normal cells (murine splenocytes). From the identification of the chemical structure of VD-3 by spectral data and chemical synthesis, the compound was proven to be epi-oleanolic acid. Tumor cells treated with VD-3 showed a typical pattern of apoptotic cell death, such as apparent morphological changes and DNA fragmentation. These results indicate that epi-oleanolic acid is an important compound responsible for antitumor activity of KM.

Purification and characterization of four isoforms of Himalayan mistletoe ribosome-inactivating protein from Viscum album having unique sugar affinity

Ribosome-inactivating proteins having antitumor and immunomodulatory properties constitute the active principle of widely used mistletoe therapy in Europe. This is the first report of the four isoforms of Himalayan mistletoe ribosome-inactivating proteins (HmRips) from Viscum album parasitized on wild apple inhabiting NW Himalayas. HmRips were purified by affinity chromatography and four isoforms were separated by ion-exchange chromatography. HmRip 1, 2, 3, and 4 have isoelectric points of 6.6, 6.1, 5.2, and 4.7, respectively. Disulfide linked toxin and lectin subunits of HmRip 1 and 2 isoforms have molecular weights of 28 and 34kDa while those of HmRip 3 and 4 have 28 and 32kDa. The isoforms lacked blood group specificity and showed positive activity with seven mammalian erythrocyte types but did not show any activity with avian erythrocyte type. Lectin activity of HmRips remained unchanged for a wide range of temperatures (0-65 degrees C) and pH (3-9). Unlike other type II Rips, the HmRip 1, 2, and 4 showed unique affinity towards l-rhamnose, meso-inositol, and l-arabinose while HmRip 3 has specificity to gal/galNAc. Sugar binding studies with 22 sugars also suggested that the C-4 hydroxyl of galactose might be the critical site involved in sugar binding of HmRips. Type II Rips are known to be galactoside specific and do not have affinity for l-rhamnose and meso-inositol. However, HmRip 1, 2, and 4 having equal affinity for galactose and l-rhamnose do not strictly fit into any of the four structural classes of the lectins and represent a new class of type II Rips and plant lectins.

Preparation of alginate/chitosan microcapsules and enteric coated granules of mistletoe lectin

The aqueous extract of European mistletoe (Viscum album, L.) has been used in cancer therapy. The purified mistletoe lectins, main components of mistletoe, have demonstrated cytotoxic and immune-system-stimulating activities. Korean mistletoe (Viscum album L. coloratum), a subspecies of European mistletoe, has also been reported to possess anticancer and immunological activities. A galactose- and N-acetyl-D-galactosamine-specific lectin (Viscum album L. coloratum agglutinin, VCA) with Mr 60 kDa was isolated from Korean mistletoe. Mistletoe preparations have been given subcutaneously due to the low stability of lectin in the gastrointestinal (GI) tract. In the present study, we investigated the possibility of alginate/chitosan microcapsules as a tool for oral delivery of mistletoe lectin. In addition, our strategy has been to develop a system composed of stabilizing cores (granules), which contain mistletoe lectin, extract or powder, coated by a biodegradable polymer wall. Our results indicated that successful incorporation of VCA into alginate/chitosan microcapsules has been achieved and that the alginate/chitosan microcapsule protected the VCA from degradation at acidic pH values. And coating the VCA with polyacrylic polymers, Eudragit, produced outstanding results with ideal release profiles and only minimal losses of cytotoxicity after manufacturing step. The granules prepared with extract or whole plant produced the best results due to the stability in the extract or whole plant during manufacturing process.

Antitumor activity of the Korean Mistletoe Lectin is attributed to activation of macrophages and NK cells

Inhibitory effect of the lectins (KML-C) isolated from Korean mistletoe (KM; Viscum album coloratum) on tumor metastases produced by murine tumor cells (B16-BL6 melanoma, colon 26-M3.1 carcinoma and L5178Y-ML25 lymphoma cells) was investigated in syngeneic mice. An intravenous (i.v.) administration of KML-C (20-50 ng/mouse) 2 days before tumor inoculation significantly inhibited lung metastases of both B16-BL6 and colon 26-M3.1 cells. The prophylactic effect of 50 ng/mouse of KML-C on lung metastasis was almost the same with that of 100 microg/mouse of KM. Treatment with KML-C 1 day after tumor inoculation induced a significant inhibition of not only the experimental lung metastasis induced by B16-BL6 and colon 26-M3.1 cells but also the liver and spleen metastasis of L5178Y-ML25 cells. Furthermore, multiple administration of KML-C given at 3 day-intervals after tumor inoculation led to a significant reduction of lung metastasis and suppression of the growth of B16-BL6 melanoma cells in a spontaneous metastasis model. In an assay for natural killer (NK) cell activity, i.v. administration of KML-C (50 ng/mouse) significantly augmented NK cytotoxicity against Yac-1 tumor cells 2 days after KML-C treatment. In addition, treatment with KML-C (50 ng/mouse) induced tumoricidal activity of peritoneal macrophages against B16-BL6 and 3LL cells. These results suggest that KML-C has an immunomodulating activity to enhance the host defense system against tumors, and that its prophylactic and therapeutic effect on tumor metastasis is associated with the activation of NK cells and macrophages.

Involvement of hydrogen peroxide in mistletoe lectin-II-induced apoptosis of myeloleukemic U937 cells

Mistletoe lectin-II, a major component of Korean mistletoe (Viscum album var. coloratum) induces apoptotic death in cancer cells. In this study, we demonstrated that lectin-II induced the generation of pro-oxidants and thus resulted in the apoptotic death of human myeloleukemic U937 cells. We observed that lectin-II-induced apoptotic death was inhibited by antioxidants including reduced glutathione (GSH), N-acetylcysteine (NAC), ebselen, mnTBP, catalase and pyrrolidine dithiocarbamate (PDTC). GSH and NAC also abolished the apoptotic DNA ladder pattern fragmentation of U937 cells after lectin-II stimulation. Obviously, lectin-II treatment of cells resulted in a remarkable generation of intracellular hydrogen peroxide (H2O2) as an early event, which was monitored fluorimetrically using scopoletin-horse radish peroxidase (HRP) assay and peroxide-sensitive fluorescent probe, DCF-DA. In addition, antioxidants inhibited the activation of c-Jun N-terminal kinase (JNK)/stress-activated protein kinase (SAPK) as well as cytosolic release of cytochrome c by mistletoe lectin-II. Moreover, lectin-II-induced activation of caspase-9 and 3-like protease and cleavage of poly(ADP-ribose) polymerase (PARP) were inhibited by pretreatment of cells with thiol antioxidants, GSH and NAC. Taken together, these results suggest that Korean mistletoe lectin-II is a strong inducer of pro-oxidant generation such as H2O2, which mediates the JNK/SAPK activation, cytochrome c release, activation of caspase-9 and caspase 3-like protease, and PARP cleavage in human myeloleukemic U937 cells.

The influence of isorel on the advanced colorectal cancer

There is still no therapy method in the colorectal cancers that is good enough for such a complex disease. Combined surgery, chemotherapy, and radiotherapy improved survival, but the side effects and the poor performance status of the patients seriously affect the use of these methods. We used a therapeutical approach of surgery and chemotherapy combined with biotherapy by Viscum album extract Isorel, aiming to improve the patients' resistance to the disease and to render the treatment's side effects more tolerable. Isorel is aqueous extract well known for its anticancer effects obtained by various in vitro and in vivo experimental models and which was validated by an in vitro bioassay on murine melanoma B16F10 and human cervical carcinoma HeLa cells. Isorel strongly reduced human colon cancer HT 29 cell line growth in vitro in the MTT bioassay. Hence, it was further used in a prospective, randomized, and controlled study which compared the postoperative results for patients with colorectal cancer stages Dukes C (40 patients) and D (24 patients) who, beside surgery, received either only chemotherapy (5-FU), 6 cycles (either the Mayo or the De Gramont protocol) or chemotherapy combined with Isorel biotherapy. These 64 patients were randomly allocated into three groups "only chemotherapy" for 21 cases, chemo + biotherapy for 29 cases and 14 patients underwent only surgery as the control group. We noted no toxic deaths due to either chemo or biotherapy. The patients operated on and treated with chemo and biotherapy had median survival significantly better and a cumulative proportion survival (Kaplan-Maier) superior to those of the patients receiving only postoperative chemotherapy. Thus, colorectal cancer patients seem to benefit in terms of survival from combined postoperative chemotherapy and Isorel biotherapy, either adjuvant or palliative.