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PubMed2006

Antioxidant activity of Viscum album ssp. album.

Methanolic extracts of Viscum album ssp. album (mistletoe) grown on different host trees were investigated for their potential antioxidant activity. Scavenging activity was tested by 1,1-diphenyl-2-picrylhydrazyl (DPPH) method and the inhibitory effect on lipid peroxidation was examined by ferric thiocyanate and thiobarbituric acid methods. The extract from mistletoe grown on lime tree in summer showed the highest activity. It was found that antioxidant capacity of the plant differed according to the harvesting time as well as the host tree.

Antioxidants↗
PubMedDate not supplied

Cytotoxic norditerpene lactones from Ileostylus micranthus.

Three new compounds 2-4 and two known compounds 1 and 5 have been isolated from the cytotoxic fraction of an extract from a New Zealand mistletoe, Ileostylus micranthus. Compounds 1-5 are shown to be norditerpene lactones and have strong cytotoxicity. The compounds are proposed to have been assimilated by the mistletoe from the host tree, Podocarpus totara.

Animals↗
PubMed2001

Different effects of lectins on the ligand binding of the NMDA receptors and sigma sites in rat brain hippocampus synaptic membranes.

The effects of the lectins concanavalin A, WGA, ricin, abrin, and the mistletoe lectins from Viscum album MLI, MLII, and MLIII on the binding of ligands of the NMDA and sigma receptors in rat hippocampus synaptic plasma membranes were investigated. Binding of [3H]MK-801, [3H]glutamate, [3H]5,7-DCKA, and [3H]glycine to the membranes was decreased by 40-60% after addition of galactose-specific lectins (mistletoe lectins MLI, MLII, ricin, abrin) at concentrations of 0.01 mg/ml, but was not affected by the glucose- and mannose-specific lectin Con A, an acetylglucosamine-specific lectin WGA, or an acetylgalactosamine-specific lectin MLIII. The binding of [3H]SKF 10047 was decreased only in the presence of MLIII and did not change after addition of the other lectins. It is suggested that lectin-sensitive ligand binding sites of sigma- and NMDA receptors are located separately, and that the carbohydrate side chains of the sigma receptor do not participate in the modulation of the NMDA-receptor.

Animals↗
PubMed2004

Cloning and expression of catalytic subunit of MLIII, the ribosome-inactivating protein from Viscum album.

We have cloned the gene encoding a precursor of mistletoe (Viscum album) toxin MLIII. Analyses of nucleotide and deduced amino acid sequences of this gene revealed significant differences between MLI and MLIII preprotoxin genes. Immunochemical properties of recombinant A-subunit expressed in Escherichia coli and renatured were investigated using a panel of monoclonal antibodies raised against three mistletoe toxins (MLI, MLII, and MLIII). Ribosome-inactivating activity of recombinant MLIII A-subunit was detected in cell-free lysate of rabbit reticulocytes.

Amino Acid Sequence↗
PubMed2004

Phase II study of viscum fraxini-2 in patients with advanced hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide. Although a wide range of therapeutic options is available, the efficacy of these methods and the prognosis of patients with HCC remain very poor. This study was conducted to evaluate the efficacy and safety of viscum fraxini-2 in patients with chemotherapy-naïve, advanced hepatocellular carcinoma. 23 patients with unrespectable HCC who had received no prior systemic chemotherapy with objectively measurable tumors were enrolled on this study. The mistletoe preparation for the study is an aqueous injectable solution. It contains one milliliter of viscum fraxini in dilution stage-2 (15 mg extract of 20 mg mistletoe herb from ash tree, diluted in di-natrium-mono-hydrogen phosphate, ascorbic acid and water) which is equivalent to 10 000 ng/ml injection ampoules. 2 ampoules of viscum fraxini-2 were administered subcutaneously once weekly. As assessed by conventional imaging criteria, 3 (13.1%) patients have achieved complete response, 2 (8.1%) patients have achieved a partial response. 9 (39.1%) had progressive disease while 9 (39.1%) patients didn't have evaluation of response due to early death. The median overall survival time for all patients was 5 months (range 2-38 months), for those who achieved a CR was 29 months (range 12-38 months) and, for those who achieved a PR was 6.5 months (range 6-7 months). The median progression free survival for all patients was 2 months (range 1-38 months), for those who achieved a CR, it was 29 months (range 8-38 months) and for those who achieved a partial response, it was 5 months (range 4-6 months). No hematologic toxicity has been encountered. The spectrum of non-hematologic toxicity was mild. The WHO toxicity criteria grade 3-4 were 34.8% drug related fever, 13.1% erthyma at injection site and 17.4% pain at the site of injection. No drug related discontinuation or toxic deaths have occurred. Viscum fraxini-2 seems to be particularly promising in patients with advanced HCC, it shows antitumor activity and low toxicity profile. Further studies in combination with other active agents are clearly warranted.

Adult↗
PubMed1985

Energy minimization for tertiary structure prediction of homologous proteins: alpha 1-purothionin and viscotoxin A3 models from crambin.

Homologous proteins may fold into similar three-dimensional structures. Spectroscopic evidence suggests this is true for the cereal grain thionins, the mistletoe toxins, and for crambin, three classes of plant proteins. We have combined primary sequence homology and energy minimization to predict the structures alpha 1-purothionin (from Durum wheat) and viscotoxin A3 (from Viscum album, European mistletoe) from the high resolution (0.945 A) crystal structure of crambin (from Crambe abyssinica). Our predictions will be verifiable because we have diffraction-quality crystals of alpha 1-purothionin whose structure we are have predicted. The potential energy minimizations for each protein were performed both with and without harmonic constraints to its initial backbone to explore the existence of local minima for the predicted proteins. Crambin was run as a control to examine the effects of the potential energy minimization on a protein with a well-known structure. Only alpha 1-purothionin which has one fewer residue in a turn region shows a significant difference for the two minimization paths. The results of these predictions suggest that alpha 1-purothionin and viscotoxin are amphipathic proteins, and this character may relate to the mechanism of action for these proteins. Both are mildly membrane-active and their amphipatic character is well suited for interaction with a lipid bilayer.

Amino Acid Sequence↗
PubMed2004

Phase I trial of intravenous aviscumine (rViscumin) in patients with solid tumors: a study of the European Organization for Research and Treatment of Cancer New Drug Development Group.

BACKGROUND: Aviscumine is an Escherichia coli-derived recombinant type II ribosome-inactivating protein with potent antitumor activity in vitro and in vivo. It is the recombinant counterpart of natural mistletoe lectin-I. The current study was performed to determine the safety profile, dose-limiting toxicity (DLT) and maximum tolerated dose (MTD) of the intravenous (i.v.) administration of aviscumine in cancer patients. Translational research included the evaluation of pharmacokinetics and monitoring of plasma cytokine and anti-aviscumine antibody induction after administration of the drug. PATIENTS AND METHODS: Aviscumine was given twice weekly as a 1 h central i.v. infusion in patients with advanced, refractory progressive, solid malignant tumors who had not been previously exposed to natural mistletoe preparations. They had histologically or cytologically verified disease, were > or =18 years old, had an Eastern Cooperative Oncology Group performance status < or =2 and adequate bone marrow, liver and renal function. DLT was defined as any non-hematological grade 3-4 toxicity (National Cancer Institute Common Toxicity Criteria version 2.0), neutrophil count <500/microl for > or =7 days, febrile neutropenia or thrombocytopenia grade 4. The MTD was defined as the dose at which >20% of patients experienced DLT during the first treatment cycle. The Continual Reassessment Method was used to determine the number of patients required per dose level. RESULTS: Forty-one fully eligible patients (19 male, 22 female) with a median age of 56 years (range 37-74) were enrolled. Colorectal, ovarian, renal cell and breast cancer were the most common tumor types. Dose levels of aviscumine ranged from 10 to 6400 ng/kg. The median number of cycles was two (range one to eight). Common clinical toxicities in cycle 1 were fatigue, fever, nausea, vomiting and allergic reactions. Fatigue grade 3 was dose limiting in one of six patients at 4000 ng/kg and reversible grade 3 liver toxicity (elevation in alkaline phosphatase, transaminases and/or gamma-glutamyltransferase) occurred in one of 10 patients at 4800 ng/kg and in two of five patients at 6400 ng/kg. The best response (RECIST criteria) was stable disease in 11 patients, lasting for two to eight cycles. The pharmacokinetic evaluation revealed a short alpha half-life of 13 min and linear kinetics on dose levels > or =1600 ng/kg. Aviscumine stimulated the immune system with a release of cytokines such as interleukin (IL)-1beta, IL-6 and interferon-gamma, and induced immunoglobulin (Ig) G- and/or IgM-anti-aviscumine antibodies of uncertain clinical relevance. CONCLUSIONS: The recommended dose for further clinical trials is 5600 ng/kg twice weekly. Based on the short half-life of the recombinant protein observed in this trial, the exploration of prolonged infusion schedules of aviscumine is warranted.

Adjuvants, Immunologic↗
PubMed2005

Winter resource wealth drives delayed dispersal and family-group living in western bluebirds.

Delayed dispersal, where offspring remain with parents beyond the usual period of dependence, is the typical route leading to formation of kin-based cooperative societies. The prevailing explanations for why offspring stay home are variation in resource wealth, in which offspring of wealthy parents benefit disproportionately by staying home, and nepotism, where the tendency for parents to be less aggressive and share food with offspring makes home a superior place to wait to breed. These hypotheses are not strict alternatives, as only wealthy parents have sufficient resources to share. In western bluebirds, Sialia mexicana, sons usually delay dispersal until after winter, gaining feeding advantages through maternal nepotism in a familial winter group. Experimentally reducing resource wealth (mistletoe) by half on winter territories caused sons to disperse in summer, even though their parents remained on the territory during the winter. Only 8% of sons remained with their parents on mistletoe-removal territories compared to 50% of sons on control territories (t(9,10)=3.33, p<0.005). This study is the first to demonstrate that experimentally reducing wealth of a natural food resource reduces delayed dispersal, facilitating nepotism and family-group living. The results clarify the roles of year-round residency, resource limitation and relative wealth outside the breeding season in facilitating the formation of kin-based cooperative societies.

Animals↗
PubMed1993

The Anticyclic Timing of Leaf Senescence in the Parasitic Plant Viscum album Is Closely Correlated with the Selective Degradation of Sulfur-Rich Viscotoxins.

Leaf senescence and abscission have been studied in the semi-parasitic plant mistletoe (Viscum album). Leaf senescence and abscission occur in the summer, when the metabolic activity of the host has reached its maximum. In contrast with their hosts, mistletoes selectively degrade only one major leaf protein during leaf senescence, the sulfur-rich viscotoxin, whereas most of the remaining leaf proteins are lost during abscission. The changes in viscotoxin content are paralleled by changes in the concentration of the corresponding mRNA. Shortly before the onset of leaf senescence, the mRNA for viscotoxin has disappeared from the leaves. The anticyclic timing of leaf senescence and the degradation of only one major leaf protein seems to reflect an adaptation of the parasite to its habitat.

Journal Article↗
PubMed2004

Structure of a novel ribosome-inactivating protein from a hemi-parasitic plant inhabiting the northwestern Himalayas.

This is the first report of the structural studies of a novel ribosome-inactivating protein (RIP) obtained from the Himalayan mistletoe (Viscum album) (HmRip). HmRip is a type II heterodimeric protein consisting of a toxic enzyme (A-chain) with an active site for ribosome inactivation and a lectin subunit (B-chain) with well defined sugar-binding sites. The crystal structure of HmRip has been determined at 3.8 A resolution and refined to a crystallographic R factor of 0.228 (R(free) = 0.271). A comparison of this structure with other type II RIPs reveals the presence of distinct structural features in the active site of the A-chain and in the 2gamma sugar-binding site of the B-chain. The conformation of the side chain of Tyr110, which is a conserved active-site residue in the A subunit, is strikingly different from those observed in other mistletoe RIPs, indicating its unique substrate-binding preference. The deletion of two important residues from the kink region after Ala231 in the 2gamma subdomain of the B-chain results in a significantly different conformation of the sugar-binding pocket. A ribosome-recognition site has also been identified in HmRip. The site is a shallow cavity, with the conserved residues Arg51, Asp70, Thr72 and Asn73 involved in the binding. The conformations of the antigenic epitopes of residues 1-20, 85-103 and 206-223 differ from those observed in other type II RIPs, resulting in the distinct antigenicity and pharmacological properties of HmRip.

Amino Acid Sequence↗
PubMed1997

Caterpillar dermatitis.

A 3-year-old girl presented with recurrent urticarial eruptions presumed due to infestation of her garden with Euproctis edwardsi, Euproctis edwardsi, the mistletoe browntail moth is a variety of hairy caterpillar widely distributed in south-eastern Australia. They are often called 'woolly bears' by children. These caterpillars possess barbed hairs that fragment readily and are difficult to extract from the skin in one piece. Itching urticarial wheals and papular eruptions can follow contact with the caterpillars or their detached hairs. The hairlets may be identified by microscopy from skin scrapings and can be removed by tape stripping or with the aid of fine forceps. The skin lesions are treated symptomatically with calamine lotion, sodium bicarbonate solution and antihistamines. Infestation with Euproctis edwardsi can be minimized by removal of mistletoe from eucalyptus trees and by spraying affected areas with white oil or carbaryl 0.1%.

Animals↗
PubMed1993

Inhibition of the adenylylation of liver plasma membrane-bound proteins by plant and mammalian lectins.

Liver plasma membrane contains four major (130-kDa, 120-kDa, 110-kDa and 100-kDa) sialic acid-containing glycopolypeptides that are able to undergo adenylylation, as well as phosphorylation (San José et al. (1990) J. Biol. Chem. 265; 20653-20661). To gain insight into the regulation of these processes, lectins are employed to probe the extent of influence of their interaction with membrane fractions for these reactions. We demonstrate that the beta-galactoside-specific lectins from bovine heart and mistletoe at low concentrations inhibit the adenylylation of this set of plasma membrane glycopolypeptides. The extent of phosphorylation of these polypeptides is also reduced although to a lesser degree. Concanavalin A, too, inhibits the adenylylation of the plasma membrane glycopolypeptides, although higher concentrations of this lectin were required, whereas wheat germ lectin has only a very small inhibitory effect. The adenylylable polypeptides were isolated by concanavalin A-agarose chromatography upon elution with mannose. In agreement with this result, control experiments with a panel of neoglycoproteins indicate that mannose residues appear to be required for the concanavalin A-induced inhibition of the adenylylation. Neoglycoproteins containing mannose 6-phosphate, lactose, fucose, or sialic acid instead of mannose lack the ability to protect the adenylylation from the inhibitory action of concanavalin A. In contrast, none of the above-mentioned neoglycoproteins, nor asialofetuin, nor galactose-containing saccharides protect the adenylylation against the inhibitory effect of both the mistletoe and bovine heart lectins, emphasizing the importance of either high affinity carbohydrate ligands in the overall process, or other ligand sites for the lectins beside carbohydrates to affect the regulation of the adenylylation system.

Adenine↗
PubMed2004

Differential effects of Viscum album extract IscadorQu on cell cycle progression and apoptosis in cancer cells.

Extracts from European mistletoe or Viscum album L. have been reported to exert cytotoxic and immunomodulatory effects in vitro and in vivo. The mechanism of this anti-tumoral activity is however, largely unknown. In this study we tested the hypothesis that IscadorQu, an aqueous fermented extract from the European mistletoe grown on oaks, induces tumor regression by cell cycle inhibition and/or interference with apoptotic signaling pathways in cancer cells. Also a possible effect on angiogenesis, which is a prerequisite for tumor growth in vivo, is studied in endothelial cell cultures. Furthermore, we examined which apoptotic signaling route is activated by staining cells for specific pro-apoptotic proteins. To characterize these properties, 6 different human cancer cell lines, one epidermis derived cell line and 2 endothelial cell cultures were incubated with different concentrations of IscadorQu. Cell cycle kinetics parameters were measured by bromodeoxyuridine (BrdU) pulse labeling and tubulin staining. Apoptotic responses were detected by M30 CytoDeath or Annexin V/propidium iodide assays. Characterization of the apoptotic pathway was performed by staining cells for active caspase 3, active caspase 8, cytochrome C and chloromethyl-X-rosamine. The results of this study show that sensitivity to IscadorQu treatment varies strongly between different cell lines. In sensitive cell lines, including tumor and endothelial cell cultures, IscadorQu caused early cell cycle inhibition followed by apoptosis in a dose-dependent manner. Apoptosis was induced by activating the mitochondrial but not the death receptor-dependent pathway.

Antineoplastic Agents↗
PubMedDate not supplied

Perioperative application of the Viscum album extract Isorel in digestive tract cancer patients.

BACKGROUND: It is assumed that perioperative immunomodulation of cancer patients can attenuate cellular and humoral deficiencies thus improving their overall health status. Mistletoe (Viscum album L.) anticancer drugs are likely candidates for such adjuvant therapy, because they do not have major adverse side-effects but have dual desirable activities; immune-modulating effects and relatively selective cytotoxicity for cancer cells. MATERIALS AND METHODS: We used the aqueous extract Isorel, which is produced from the entire plant and is validated for batch consistency. The study involved 70 cancer patients, divided into two groups: Isorel-treated group of 40 patients who received Isorel for 2 pre- and 2 post-operative weeks (1 esophageal, 16 gastric, 2 pancreatic and 21 colorectal carcinomas) and the age- and sex-matched control group of 30 patients that did not receive Isorel (2 esophageal, 9 gastric, 3 pancreatic, 1 ileac and 15 colorectal carcinomas). Blood samples were obtained to study parameters of the immune system before the surgery and the drug administration (DO) and on the postoperative days 1 and 14 (D1, D14). The overall health status was evaluated after 60 days by the Kamofsky Performance Index and by the Analogic Scale of Anxiety. The results were compared by Student's t-test and one-way ANOVA test. RESULTS: Isorel significantly attenuated the immuno-suppressive effects of surgery observed for the Isorel-treated group, increasing the number of NK cells, the T and B cells, in particular T-helper cells, complement, IgA, IgG and IgM values also in comparison to the respective D0 values. Both the Kamofsky status and the Anxiety Scale improved remarkably in Isorel-treated patients in comparison to the control. CONCLUSION: The results of this study indicate that perioperative use of the mistletoe drug Isorel can improve immune competence and the overall health status of cancer patients undergoing surgery.

Adult↗
PubMed1996

A nonradioactive assay for ribosome-inactivating proteins.

A sensitive nonradioactive method to determine the activity of ribosome-inactivating proteins (RIPs) based on a combined transcription/translation in vitro assay was established. Using this assay we investigated the RIP activities of the heterodimeric toxic plant lectins ricin and mistletoe lectin I (ML-I). The enzymatic activities of the holoproteins were compared to that of the RIP-active chain of ML-I (ML-I A-chain) and recombinant ML-I A-chain expressed in Escherichia coli. The IC50 values determined for the plant toxins showed that the translation-inactivating activity of ML-I (39.8 pM) is about four times higher than that of ricin (176.0 pM). The plant-derived ML-I A-chain is more toxic (3.4 pM) in the cell-free translation system than the respective holoprotein. The recombinant ML-I A-chain was found to be about three times less active (IC50 10.6 pM) than the A-chain from plant. The in vitro assay described here is a convenient method for the fast determination of RIP activity with a 1000-fold lower detection limit than that of commonly used RIP assays.

Animals↗
PubMed1991

Improvement of DNA repair in lymphocytes of breast cancer patients treated with Viscum album extract (Iscador).

We investigated alteration in DNA repair during therapy with an immunomodulator. 14 patients with advanced breast cancer were treated parenterally with Iscador, an extract of Viscum album (mistletoe). As a parameter for measurement of DNA repair the incorporation of (3H) thymidine into DNA of unstimulated lymphocytes after ultra violet light (UV) damage was taken. The DNA repair values in the patients were very low before treatment and on day 1: on average 16% of those in a healthy control population. Values started to increase on day 2 and on days 7-9 were on average 2.7 times higher than before treatment. 12/14 patients showed an improvement in repair. The values of spontaneous DNA synthesis were not altered during the treatment. We suggest that the increase of DNA repair could be due to a stimulation of repair enzymes by lymphokines or cytokines secreted by activated leukocytes or an alteration in the susceptibility to exogenic agents resulting in less damage.

Adult↗
PubMed1990

Changes in sensitivity of the isolated guinea-pig vas deferens induced by a lyophilized Phoradendron latifolium leaf infusion.

The effect of a lyophilized mistletoe infusion (LMI) was studied on isolated guinea-pig vas deferens. LMI caused a contraction which was partially blocked by phentolamine but not by atropine. LMI caused a shift to the left of the norepinephrine concentration-effect curve (CEC), an effect which appeared to be blocked by atropine and was absent in animals previously treated with reserpine and alpha-methyl-para-tyrosine. The increase of the norepinephrine maximal response induced by LMI was not blocked by atropine or pharmacological denervation. LMI caused a shift to the right of the acetylcholine CEC and had no effect on the acetylcholine maximal response. These results suggest that the effects seem to be due mainly to the presence of potassium ion in the LMI; however, the participation of muscarinic agonist(s) of reduced intrinsic activity or some tyramine-like substance could not be ruled out.

Acetylcholine↗
PubMed1995

Viscum album agglutinin-induced aggregation of blood cells and the lectin effects on neutrophil function.

Extracts from mistletoe enjoy a large popularity in central Europe as an unconventional treatment modality for cancer, warranting scientific efforts with defined components to delineate any potential benefit. The galactose-specific lectin from Viscum album (VAA), known to exhibit immunomodulatory and ensuing antitumoral capacities in animal model systems, was shown to aggregate human blood cells in the following order: neutrophils, mononuclear cells--thrombocytes and erythrocytes. To contribute to the analysis of lectin effects on individual aspects of the host defence system, two parameters of neutrophils were quantitatively assessed, namely the aggregating activity of VAA as a measure of strength of interaction with cell surface ligands and the effect of lectin on oxidative metabolism (H2O2 release) of these cells. It was found that whole lectin and its carbohydrate-binding B-subunit possessed the capacity to induce cell aggregation and H2O2 release, which were blocked by D-galactose and lactose. Both effects displayed similar dependence on the lectin concentration in the range 0.1-25 micrograms/ml. The toxic A-subunit displayed detectable activity only in high doses (50 micrograms/ml) while the bovine heart galaptin (14 kDa; galectin-1) failed to affect neutrophils. The role of oxidative metabolism in regulation of neutrophil aggregation induced by VAA was studied using metabolic inhibitors and controlled heating at 46 degrees C leading to inhibition of plasma membrane NADPH-oxidase system. Trifluoperazine and menadione inhibited the neutrophil aggregation in a dose-dependent manner in comparison with such inhibitors as amiloride and theophylline.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Cells↗