Isolation of a crystalline toxic factor from agenized wheat flour / by P.N. Campbell and Sir Edward Mellanby.

  • Peter Nelson Campbell
Date:
[1950?]
Catalogue details

Licence: In copyright

Credit: Isolation of a crystalline toxic factor from agenized wheat flour / by P.N. Campbell and Sir Edward Mellanby. Source: Wellcome Collection.

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    a dose of 100 gm. (1*9 gm. nitrogen) fed over three days. Gluten was separated from the flour and digested first with pepsin and then with trypsin. The digest was dialysed and the dialysate hydrolysed for four hours with strong hydrochloric acid. The acid was removed and the hydrolysate electrodialysed. The neutral fraction from the electrodialysis was treated with sufficient charcoal to remove the aromatic amino-acids5, and the residual neutral amino-acid mixture was then fractionated on a ‘Zeokarb 215’ column by the method of Partridge6. A fraction was obtained from the ‘Zeokarb’ column which produced a typical fit in a ferret when fed for three days at a level of 17 mgm. nitrogen per day. This active material contained at least fifteen com¬ ponents and was further fractionated by chromato¬ graphy on a paper column (‘Solka Floe’) using a mixture of butanol, acetic acid and water as solvent. The toxic factor crystallized when the appropriate fraction of the effluent was concentrated. Toxicity The crystalline toxic factor (see accompanying illustration) produced severe epileptiform fits in a ferret when fed for five days at a level of 100 ggm. nitrogen per day ; this represents a total dose of crystalline material of approximately 3 mgm. The pure toxic factor is thus 33,000 times as toxic as the original flour. When fed as a single dose the crystalline material is slightly more toxic than when the dose is spread over several days. A single dose of 2 mgm. is sufficient to produce typical epileptiform fits in a ferret, and a slightly greater dose kills the animal. Particular emphasis must be laid, however, on the cumulative nature of the poisonous effect. We have demon¬ strated in the ferret that a fatal toxic reaction can be produced by feeding the concentrated toxic factor in small doses over a period of five to ten days, and that the daily intake in such cases is only a fraction of the dose required to produce an immediate toxic response. It must be added, however, that this toxic action is not a simple problem and is probably influenced by other elements in the diet. Nature of the Toxic Factor As the amount of toxic factor in flour is small (1 gm. per 33,000 gm. flour) and the isolation procedure gives an overall yield of only 10 per cent, the greatest difficulty has been experienced in obtaining sufficient material for combined biological and chemical characterization. All the results re¬ ported below have been obtained, on gbout 10 mgm, of crystalline toxic factor,
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