Effect of Ether Peroxides in Wheat Germ Oil on Production of Tumors in Rats

Abstract

Rowntree and associates 1 have reported a high incidence of abdominal sarcoma in Wistar rats, as well as albino rats from the Buffalo and Yale strains, when fed crude wheat germ oil prepared by ether extraction. Great variability occurred in the rate of tumor production. In rats given 1 cc of oil daily tumors appeared in about 100 to 200 days; with 4 cc daily the average was about 54 days. The nature of the neoplastic agent has not been determined but since it appears to be absent from refined ether-extracted wheat germ oil, and wheat germ oils not obtained by means of ether, it is possible that the factor is produced by some action of ether on wheat germ. Owing to the tendency of unsaturated fatty compounds to undergo oxidation while in contact with ether containing peroxides 2 it appeared to us that the neoplastic agent might have arisen through the action of such peroxides, formed in the extraction of wheat germ with ether, although the latter was reported to be peroxide-free before it was used.

We have tested this hypothesis as follows: Two volumes of C. P. peroxide-free anhydrous ether were added to one volume of fresh cold pressed wheat germ oil∗ in a glass flask fitted with a condenser. This oil was aerated seven hours by means of a slow current of air drawn through H₂SO₄ and glass wool. The mixture was allowed to remain in the flask at room temperature for 36 hours, without protection from light, after which most of the ether was removed by distillation at atmospheric pressure. The mixture was then placed in an evaporating dish and heated on a water bath for 2 to 3 hours, with occasional stirring to remove most of the ether that remained.