DIGESTION AND ABSORPTION OF HYDROCARBONS 279 



eight different compounds have been reported from olive oil, ranging in 

 composition from C13H24 to C 28 H5o. 196 ' 197 For a more complete discussion 

 of these hydrocarbons, the reader is referred to Volume I (pages 400-404) 

 of this monograph. 



Channon 198 has demonstrated that squalene is absorbed by the rat and 

 appears in the liver and body fat as a component of the nonsaponifiable 

 extract. The storage of squalene in the liver and tissues is only temporary, 

 since it begins to decrease as early as eight days after the rats are trans- 

 ferred to the control diet. 



(3) Carcinogenic and Related Non-carcinogenic Hydrocarbons 



A number of hydrocarbons and related compounds have been found to 

 be potent carcinogenic agents. Cook and Haslewood, 199 in 1934, demon- 

 strated that methylcholanthrene is capable of initiating malignant growth 

 in test animals. It is now generally recognized that this hydrocarbon is 

 the most potent carcinogenic agent known. It is able to produce tumors 

 of various types. Methylcholanthrene has been synthesized by an 

 anomalous degradation of cholesterol. 2op It was also produced in a 5.4% 

 yield by Fieser and Newman 201 as a degradation product of cholic acid, 

 through dehydrocholic acid and 3,7-dihydroxy-12-ketocholanic acid; 

 when desoxycholic acid was degraded, the yield was 4.3%. Since it is 

 possible to synthesize it in the laboratory from such natural products as 

 cholesterol and bile acids, Fieser and Fieser 202 suggest that this substance 

 may arise in the body through a process of abnormal metabolism, and so 

 may initiate cancer. However, the degradations of desoxycholic acid, 

 cholic acid, and cholesterol have not been effected under conditions which 

 approach physiologic ones. Moreover, there is no proof that methyl- 

 cholanthrene or any other hydrocarbon carcinogen plays any role in the 

 etiology of human cancer. 202 It is possible, however, that a trace of 

 methylcholanthrene could produce a few malignant cells which, by cell 

 division and without further stimulation by the proliferating agent, 

 could initiate the abnormal metabolism resulting in the formation of con- 

 siderable cancerous tissue. This might follow an induction period during 

 which the original exciting agent had been eliminated from the body. 



197 G. Sani, Atti accad. Lined, 12, 238-242 (1930). 



198 H. J. Channon, Biochejn. J., 20, 400-408 (1926). 



199 J. W. Cook and G. A. D. Haslewood, J. Chem. Soc, 1934, 428-453. 



200 W. Rossner, Z. physiol. Chem., 249, 267-274 (1937). 



201 L. F. Fieser and M. S. Newman, J. Am. Chem. Soc, 57, 961 (1935). 



202 L. F. Fieser and M. Fieser, Natural Products Related to Phenanthrene, 3rd ed., 

 Reinhold, New York, 1949. 



