Isolation of viscotoxins, cytotoxic basic polypeptides from VISCUM ALBUM L.

Journal/Book: Hoppe-Seyler's Z. Physiol. Chem. 361, 1525-1533. 1980;

Abstract: In the course of cytotoxicity-directed fractionation of extracts fromViscum album L., it appeared that crude viscotoxin, a basic polypeptidefraction, is responsible for cytotoxic properties of the plant examined.Separation of this fraction by ion exchange chromatography oncarboxymethylcellulose led to isolation of five cytotoxic components.Four of them, named viscotoxins I, II, III and IVb were obtained ashomogeneous substances. The isolated polypeptides exhibited cytotoxicactivity against human tumor cells of KB and HeLa lines in tissueculture in the concentration range (ED50 values) of 0.2-1.7microgram/ml. Considerably decreased activities were found when tissueculture was contaminated with mycoplasma. The estimated molecularweights (about 5000) and the amino acid compositions suggest theviscotoxins II, III and IVb are identical to viscotoxins B, A-2 and A-3,respectively. The latter three viscotoxins have been isolated previouslyby others as toxic (cardiotoxic) components of Viscum album. Thefractionation of the crude viscotoxin was carried out by a newprocedure, considerably simpler than that described for isolation ofviscotoxins B, A-2 and A-3 Author.

Keyword(s): AMINO-ACIDS/AN (analysis)

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