Nov. IS. 191S Gossypol, the Toxic Substance in Cottonseed Meal 271 



TOXICITY OF PRECIPITATED GOSSYPOIv 



By the term "precipitated gossypol" we designate a product obtained 

 from the gossypol extract. In securing the extract in larger quantities 

 the oil was not entirely removed from the cottonseed kernels by several 

 previous extractions with gasoline; hence, the gossypol extract contained 

 considerable amounts of oil. The dark-red oily gossypol extract, after 

 evaporation of the ethyl ether, was mixed with a large quantity of 

 petroleum ether. Under some conditions a part of the gossypol precipi- 

 tated in brown flocks, which could be separated easily by filtration. 

 Under conditions of rapid precipitation these flocks would agglomerate 

 and form a red resinous material. Both the light-brown powder and 

 the red resinous material dissolved in ether very readily, giving a deep 

 cherry-red solution. 



Another artificial cottonseed meal was prepared by dissolving weighed 

 quantities of precipitated gossypol in ether, pouring the solution over 

 corn meal, and warming over a steam bath to drive off the ether. One 

 gm. of precipitated gossypol was usually mixed with 50 gm. of corn 

 meal. This proportion was based on the assumption that gossypol 

 existed in cottonseed kernels to the extent of 2 per cent. 



Our earlier estimate of 2 per cent appears to be too high. The largest 

 yields of crystalline gossypol acetate secured from the extract were from 

 0.8 per cent to i per cent of the weight of the kernels. This probably 

 represents nearly the entire amount present, as very little gossypol is 

 dissolved by gasoline and little is left after ether extraction, judging by 

 the slight toxicity of the residue. 



Pouring the deep cherry-red solution over corn meal gave it a red 

 color. When this was warmed over the steam bath, the color of the 

 corn meal changed to a typical cottonseed-meal yellowish brown. No 

 explanation is offered for this change; but it is evidently not due to 

 oxidation, as the change begins at the bottom of the mixture, not at 

 the surface. 



This artificial meal was fed to six rabbits and proved fatal in every 

 case. We had difficulty in getting them to eat it after having been once 

 made sick. 



Rabbit 954 was taken from feed 318 (gossypol extract) and offered 

 com meal and molasses containing 0.37 gm. of precipitated gossypol. 

 It ate an equivalent of 0.3 gm. of the precipitated gossypol by the second 

 day and seemed slightly indisposed. A week later it was again put on 

 this feed, at the rate of 0.2 gm. daily. The quantity of gossypol eaten in 

 the first six days was, per day, 0.2, 0.2, 0.17, o.io, o, and 0.05 gm. It 

 ate none after this, but became sicker and died six days later. 



Rabbit 961 ate 0.9 gm. of precipitated gossypol mixed with corn meal 

 and molasses. It was apparently normal the next day, but refused 

 cabbage on the third day. Thereafter it ate green feed well, but seemed 

 to have no appetite for corn meal and molasses except when very hungry. 



