Zur Kenntnis des Viscotoxins

Winterfeld, K.; M, Leiner

doi:10.1002/ardp.19562890706

Cited by 6 publications

(5 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The synthetic method employed for 2-hydroxyquinolizidine was essentially that of Counsell and Soine (2) with incorporation of certain modifications in the synthesis of the intermediate ethyl 2-pyridyl acetate as described by Winterfeld and Flick (7).…”

Section: Discussionmentioning

confidence: 99%

“…Hydroxyquinolizidine.-2 -Pyridylacetonitrile.-This compound was prepared according to the method of Winterfeld and Flick(7) in 77.4% yield as a light yellow oil, b.p. 95-97' (3.7mm.…”

mentioning

confidence: 99%

“…160-162" (reported, m.p. 155157' (9)).Ethyl Z-Pyridylacetate.-It was prepared according to the Winterfeld and Flick procedure(7) in a yield of 75.1% as a greenish-yellow liquid, b.p. 90-91' (0.3 mm.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Esters of Bicyclic Aminoalcohols IV

Patel

Soine

1963

Journal of Pharmaceutical Sciences

View full text Add to dashboard Cite

Section: Discussionmentioning

confidence: 99%

“…Hydroxyquinolizidine.-2 -Pyridylacetonitrile.-This compound was prepared according to the method of Winterfeld and Flick(7) in 77.4% yield as a light yellow oil, b.p. 95-97' (3.7mm.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Esters of Bicyclic Aminoalcohols IV

Patel

Soine

1963

Journal of Pharmaceutical Sciences

View full text Add to dashboard Cite

“…Andreae & Good (1955) identified indolylacetylaspartic acid in pea seedlings. Winterfeld & Leiner (1956) reported further studies on viscotoxin fractions, and now consider that these are composed of amino acid and carbohydrate residues only. A few of the isolations of less well-defined products are mentioned below where relevant to the discussion.…”

Section: Discussionmentioning

confidence: 99%

Bound amino acids in protein-free extracts of Italian ryegrass

Synge¹,

Wood²

1958

Biochemical Journal

View full text Add to dashboard Cite

3214. Use of the inhibitors fluorocitrate and parapyruvate shows that the interconversion of substrates before the formation of 8-aminolaevulic acid is consistent with an active tricarboxylic acid cycle.5. Succinate inhibits the synthesis of 8-aminolaevulic acid by suppressing the formation of succinyl-coenzyme A from citrate, i8ocitrate or ooxoglutarate after itself being first converted into fumarate, malate or oxaloacetate. The inhibition is reversed by increasing concentrations of citrate or wocitrate, but is potentiated by a-oxoglutarate.6. a-Oxoglutarate added exogenously inhibits the condensation of glycine and succinyl-coenzyme A in the formation of 8-aminolaevulic acid. 7. 5:6-Dimethylbenzimidazole also inhibits the condensation of glycine and succinyl-coenzyme A. The inhibition here is partly relieved by increasing concentrations of glycine, but not by increasing concentrations of pyridoxal 5'-phosphate.Protein-free diffusates from ryegraes were studied by Synge (1951), who showed that, whilst the greater part of the nitrogen is present as free amino acids, a substantial proportion (usually about 5 % of the nitrogen of the diffusates) could be segregated in the form of chemically bound amino acids which could be set free by acid hydrolysis. These fractions of diffusate, obtained by electrical transport in a diaphragm cell, contained also much carbohydrate; their nitrogen content was not usually much more than 01I % on dry matter. In the present paper we describe subsequent experiments aimed at characterizing more closely the forms in which bound amino acids occur in diffusates from grass. We have worked chiefly with Italian ryegrass (Lolium multiflorum Lam.), but have not found any essential differences from results previously obtained with perennial ryegrass (L. perenne L.). A few isolated experiments with diffusates from such diverse leaves as those of clover, raspberry, nettle, cabbage and potato showed that by the diaphragm-cell procedure

show abstract

“…The viscotoxins are toxic proteins from Viscum album L., isolated first by Winterfeld and co‐workers [1] and by Samuelsson and co‐workers [2,3]. They are related to the family of α‐ and β‐thionins, a group of highly basic cysteine‐rich polypeptides found in the endosperms of several Gramineae, which consist of 45–47 amino acids, and have three or four disulfide bridges (reviewed in [4]).…”

mentioning

confidence: 99%

Accidental cell death and generation of reactive oxygen intermediates in human lymphocytes induced by thionins from Viscum album L.

Büssing

Stein

Wagner³

et al. 1999

European Journal of Biochemistry

View full text Add to dashboard Cite

The cytotoxic mechanisms of thionins from Viscum album L., the viscotoxins, were investigated in human granulocytes and lymphocytes. The time course of viscotoxin effects indicate accidental cell death, i.e. membrane permeabilization, degradation of cytoplasm and chromatin, swelling of mitochondria with loss of their cristae, and generation of reactive oxygen intermediates within 1±2 h, followed by secondary apoptosis-associated events. The viscotoxin homologue purothionin from whole-wheat flour and viscotoxin B, however, did not induce cell death in cultured lymphocytes. Cytotoxicity of cationic and amphipathic viscotoxin was prevented only by cleavage of its disulphide bridges.Keywords: thionins; viscotoxins; reactive oxygen intermediates; apoptosis.The viscotoxins are toxic proteins from Viscum album L., isolated first by Winterfeld and co-workers [1] and by Samuelsson and co-workers [2,3]. They are related to the family of a-and b-thionins, a group of highly basic cysteine-rich polypeptides found in the endosperms of several Gramineae, which consist of 45±47 amino acids, and have three or four disulfide bridges (reviewed in [4]). Several thionins have been sequenced and they appear to be highly homologous at the amino-acid level [4,5]. The cysteine residues, which form three disulfide bridges, the thyrosine residue at position 13, and in addition, the distribution of hydrophobic and hydrophilic residues are highly conserved [4±7]. Because of their positive charge, thionins interact with the negatively charged phospholipids making up the membranes, resulting in either pore formation or a specific interaction with a specific lipid domain [4]. The positively charged viscotoxins were found to form complexes with the negatively charged DNA, resulting in protection of the double helix against thermal denaturation [8], but, leaving the DNA conformation unaffected.Thionins are toxic to laboratory animals, insect larvae, bacteria, yeasts and mammalian cells (reviewed in [4,9]). However, there are only few reports concerning the cytotoxicity of viscotoxin to cultured cell lines. Konopa et al. [10] reported that the isolated polypeptides exhibited cytotoxic activity against the human tumour cell lines KB and HeLa in a concentration range (ED 50 ) of 0.2±1.7 mg´mL 21 . Surprisingly, Yoshida sarcoma cells were found to be more sensitive to viscotoxin than the leukaemia cell line . However, the mechanisms of viscotoxin-mediated cytotoxicity are unclear.To analyse their cytotoxic properties, we cultured peripheral blood cells with thionins from mistletoe (viscotoxin) and from whole-wheat flour (purothionin), and apoptosis-inducing proteins [12] such as mistletoe lectin (ML I) and the RNA synthesis-inhibiting Streptomyces toxin actinomycin D. The galactose-binding ML I belongs to the family of ribosomeinhibiting proteins with a lectin B chain linked by hydrophobic bonds and disulfide bridges to the catalytic A chain, which is a highly specific N-glycosidase and cleaves the N-glycosidic bond of at least one particular adenin...

show abstract

Zur Kenntnis des Viscotoxins

Cited by 6 publications

References 3 publications

Esters of Bicyclic Aminoalcohols IV

Esters of Bicyclic Aminoalcohols IV

Bound amino acids in protein-free extracts of Italian ryegrass

Accidental cell death and generation of reactive oxygen intermediates in human lymphocytes induced by thionins from Viscum album L.

Contact Info

Product

Resources

About