The isolation of a toxic substance from agenized wheat flour / by P.N. Campbell and T.S. Work and E. Mellanby.

  • Campbell, P. N. (Peter Nelson)
Date:
[1951?]
Catalogue details

Licence: In copyright

Credit: The isolation of a toxic substance from agenized wheat flour / by P.N. Campbell and T.S. Work and E. Mellanby. Source: Wellcome Collection.

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    [From THE BIOCHEMICAL JOURNAL, Vol. 48, No. 1, pp. 10(3-113, 1951] [All rights reserved] printed in great Britain The Isolation of a Toxic Substance from Agenized Wheat Flour By P. N. CAMPBELL and T. S. WORK National Institute for Medical Research and E. MELLANBY Nutrition Building, Mill Hill, London, N. W. 7 (Received 10 June 1950) In 1937, Melnick & Cowgill reported the occurrence of ‘ running fits ’ in dogs when gliadin was the sole source of protein in the diet. Similar symptoms were not produced when gliadin was replaced by other proteins. The authors concluded that a toxic sub¬ stance accumulated in the body when gliadin was fed. Wagner & Elvehjem (1944) examined the effect of adding various supplements to a gluten-rich diet and also concluded that ‘running fits’ were caused by a toxic substance in wheat products rather than by any nutritional deficiency. In 1946, Mellanby showed that wheat flour which had been ‘improved’ by treatment with nitrogen trichloride (agenized flour) produced symptoms in dogs similar to running fits; a flour which had not been agenized was not toxic. Much wheat is grown to-day which, if freshly milled, produces flour which is unsuitable for use in baking. If, however, such wheat is allowed to become aged or ‘oxidized’ by means of long periods of storage and is then milled, the resulting flour has greatly improved baking properties. This ‘ oxidizing ’ process can be more quickly brought about by the use of various oxidizing agents or ‘ improvers ’ on the flour. Nitrogen trichloride (‘agene ’) was introduced as an artificial ageing agent by Baker (1921), hence the term agenized flour. The use of nitrogen tri¬ chloride has gradually spread, both in this country and in the United States, until in 1946 it was estimated that over 90% of the flour milled in England was treated with nitrogen trichloride. A review, in which the use of oxidizing agents in the treatment of flour is discussed, has been published by Blish (1945). When agenized flour forms a substantial part of [the diet of dogs, the animals become progressively fnore restless over a period of days and eventually ievelop epileptiform fits. If the diet is replaced at his stage by an exactly similar diet containing un¬ seated flour the animals recover, but if the diet of (genized flour is continued the animals become pro¬ gressively worse and die. Similar fits cannot be )roduced by unagenized flour (Mellanby, 1946) so hat it must be assumed that the gliadin used by lelnick & Cowgill (1937) had been treated with gene, There are striking differences in the susceptibility of different species to the toxic action of agenized flour. Mellanby (1947) showed that the ferret was nearly as sensitive as the dog, but that rats and mice did not develop fits. Newell, Erickson, Gilson, Gershqff & Elvehjem (1947) showed that guinea pigs and chicks were not susceptible, and Radomski, Woodard & Lehman (1948) showed that rabbits developed typical fits. When the present investigation was begun it was already known (Mellanby, 1947) that the toxicity of agenized flour was associated with the gluten fraction, and that other proteins could also be rendered toxic by treatment with nitrogen tri¬ chloride (Moran, 1947). In view of the widespread use of agenized flour it became important to isolate and determine the nature of the toxic substance present in wheat flour. The present communication is concerned with the method used in the isolation of the substance and with its properties. A preliminary account of this work has already been published (Campbell, Work & Mellanby, 1950). The ferret has been used as the test animal and the toxic dose has been regarded as that quantity of material which would produce a typical epileptiform fit. While the present work was in progress Bentley, McDermott, Pace, Whitehead & Moran (19496) isolated from zein treated with nitrogen trichloride a crystalline substance which was toxic to rabbits. As indicated in the appropriate section this material appears to be identical with the material isolated by us from wheat flour. MATERIALS AND METHODS As an example of the methods used in the isolation of the toxic substance from agenized wheat flour, the treatment of a typical batch by the method finally adopted is described. Details showing the course of the isolation, the losses in¬ volved and the toxic dose at each stage are to be seen in Table 1. It should be emphasized that the figures quoted in this table are in some cases only an approximation; for although the losses in toxicity and the variation in the toxic dose which resulted from each step were determined, it was not possible to carry out each determination during the course of the fractionation of the same sample of wheat flour owing to the large quantities of material required for each