296 VII. ACIDS, AMIDES, ALDEHYDES AND HYDROCARBONS 



duced in the /?-position of lauric acid, a much larger proportion undergoes 

 co-oxidation than is normally the case. Presumably, w-oxidation is called 

 into play because the partial storage in the fat depots available to lauric 

 acid is not open to the phenyl-substituted lauric acid, and it must be re- 

 moved from the body by any method of oxidation which can be made avail- 

 able. 



(4) Miscellaneous Substituted Acids 



Aliphatic acids which contain a tertiary carbon atom are oxidized with 

 greater difficulty in the animal body. Moreover, they may be detoxicated 

 by conjugation with glucuronic acid, and are the only instances which 

 have been reported of the conjugation of glucuronic acid with an aliphatic 

 fatty acid. Thus, Dziewiatkowski and Lewis ^^ reported that pivalic or 

 trimethylacetic acid, 



CH3 



CHa-C-COOH, 



i, 



and tertiary butylacetic acid, 



CH3 

 CH3CCH2COOH, 

 /H3 



i, 



were practically completely excreted in unoxidized form by both rats and 

 rabbits. Moreover, it was shown that they were excreted largely in the 

 form of labile conjugated glucuronides. In a later study, Dziewiatkowski 

 et al.^* reported that methylneopentylacetic acid, 



CH3 CH3 



CH3CCH2CHCOOH, 



CH3 



was oxidized with difficulty in the organism of the rat and rabbit; its ad- 

 ministration likewise led to the excretion of large amounts of extra glucu- 

 ronic acid, presumably in combination with the unchanged acid. How- 

 ever, the excretion of aliphatic fatty acids as glucuronides was apparently 

 not Hmited to those acids having a tertiary carbon, since it was likewise 



13 D. D. Dziewiatkowski and H. B. Lewis, /. Biol. Chem., 158, 77-87 (1945). 

 '^ D. D. Dziewiatkowski, A. Venkataraman, and H. B. Lewis, J. Biol. Chem., 178, 

 169-177 (1949). 



