ROLE OF BILE IN LIPID ABSORPTION 



89 



argue that the animal body mediates reactions which favor the production 

 of its own characteristic type of bile acid. The nature of some of these 

 reactions can be demonstrated by following the changes of various types of 

 bile acids in different species of animals. 



(a) Reduction of Ketocholanic Acids. Most animals possess the ability 

 to reduce a triketo bile acid completely to the corresponding trihydroxy 

 compound, or partially to the dihydroxy compound, with the simultaneous 

 loss of an oxygen molecule. Takamori 488 demonstrated that staphylococci 

 and pneumococci reduced dehydrocholic acid (3,7,12-triketocholanic acid) 

 not only at C 3 and C 7 but also on Ci 2 to produce cholic acid (7). As 

 an example of a less complete reduction, Kim 489 reported that desoxy- 

 cholic acid resulted after the intravenous injection of dehydrocholic acid 

 in rabbits. Although desoxycholic acid is not a normal constituent of the 

 bile of guinea pigs, 418,490 Sasaki 490 was able to demonstrate the presence of 

 small amounts of it in the bile of this species after massive doses of dehydro- 

 cholic acid. 



O CH 3 



/ft) 



. r " 



() o 



Oehvdrocholic acid 



OOOII 



COOH 



Desoxycholic acid 



Conversion of Dehydrocholic Acid to Desoxycholic Acid 



after Feeding of Massive Doses to Guinea Pigs (7) 



When reductodehydrocholic acid (3a-hydroxy-7,12-diketocholanic acid) 

 is given to guinea pigs, desoxycholic acid is formed, which is excreted in the 

 bile as the free desoxycholic acid or as the glycodesoxycholic acid. 491 



488 M. Takamori, J. Biochem. (Japan), 89, 255-258 (1952). 



489 C. H. Kim, Z. physiol. Chem., 255, 267-270 (1938). 



490 T. Sasaki, J. Biochem. {Japan), 82, 87-90 (1940). 



491 T. Sasaki, J. Biochem. (Japan), 82, 81-8G (1940). 



