Gossypol, the Toxic Substance in Cottonseed

Since our previous publication (17) on this subject, several articles have appeared in which other explanations of cottonseed-meal poisoning have been offered. Thus, Rommel and Vedder (14) have suggested that poisoning by cottonseed meal is similar to beriberi, and is caused by deficient diets. This view was based on the similarity of post-mortem symptoms noted in pigs fed on rice and tankage. Wells and Ewing (15) have concluded that cottonseed-meal injury is due in large part to incomplete diets. Richardson and Green (JJ) fed white rats and concluded that cottonseed meal and flour are not actively toxic, but contain insufficient minerals and possibly inadequate amounts of the fat-soluble growthpromoting substance. Osborae and Mendel (JO) have secured results similar to those of the last-named authors with cottonseed meal and flour, but on subsequently feeding raw cottonseed kernels supplied by us, they have corroborated the results which we had obtained with the kernels. They admit the presence of a deleterious substance in raw cottonseed, but apparently still hold the view that cottonseed meal, the product resulting from cooking the kernels and pressing out the oil, is nontoxic, at least for rats and chickens (9). Inasmuch as no comparative experiments with an isolated and purified substance have been reported, we present the results of additional experiments with various animals to supplement those given in our previous experiments, in which rabbits and fowls were used. The toxic effect of an ether extract of raw cottonseed has been well shown in the rat-feeding experiments described by McCollum and coworkers (6) and by Osborae and Mendel (JO). This extract contains about 2 per cent of gossypol, which is equivalent to about 0.6 per cent of the weight of the kernels from which the extract is obtained. Our rat diet, containing 20 per cent of this extracted oil, caused prompt decline in grown rats. Osborae and Mendel (JO) used as little as 1 per