712 VII. VITAMINS A 



TABLE 11 

 Thermal Decomposition of Kitol" 



« N. D. Embree and E. M. Shantz, ./. Am. Chem. Soc, 65, 910-913 (1943). 



Kitol is resistant to treatment with N /ZQ alcoholic hydrogen chloride; 

 after neutralization, the recovered material yields vitamin A on pyroly- 

 sis. On the other hand, no vitamin A can be obtained from the reaction 

 product of kitol and antimony trichloride. Kitol can be readily separated 

 from vitamin A because it is more strongly adsorbed by alumina on the 

 chromatographic column than is vitamin A. 



Hickman ^^^ has suggested that kitol may be a detoxication product of 

 vitamin A. It has therefore been suggested that it should be considered 

 as a post- rather than as a provitamin A. Since it is well known that most 

 mammals are unable to tolerate as large quantities of vitamin A as can most 

 fishes, it was suggested that a mammal such as the whale, finding itself em- 

 barassed by the large intake of vitamin A in its marine diet, develops a 

 method for changing it into the non-toxic product kitol. 



However, this earlier suggestion that kitol is a detoxicant now appears 

 open to question. The presence of kitol in the liver oils of sheep and oxen, 

 in spite of their relatively low vitamin A intake, would seem to preclude 

 this explanation. Moreover, the rat does not form kitol even if given ex- 

 cessive amounts of the vitamin. ^^^ Finally, the fact that such fishes as the 

 dog-fish and shark, which are considered relatively immune to vitamin A 

 toxicity, also form kitol would appear to render the detoxication theory 

 untenable. 



The following procedures ^^'^ have been used for the preparation of crystal- 

 line kitol: a whale liver oil containing 0.8% kitol and 21,000 I.U. vitamin 

 A per gram was used as the starting material. The preliminary concentra- 

 tion was effected by saponification, after which the sterols and other con- 

 taminants were removed from the non-saponifiable extract by low-tempera- 

 ture crystallization from acetone. The resulting oil was then mixed with a 

 constant yield oil, and the mixture was distilled in a molecular still accord- 



>^' E. M. 81ia.Titz, Personal ronnfinninilian, Scjjt, 29, 1948. 



