ROLE OF BILE IN LIPID ABSORPTION 73 



series occurs during its isolation. Wieland and Kishi 417 reported the pres- 

 ence of a keto acid in cattle bile, namely 3-hydroxy-12-ketocholanic acid. 

 Other mono-keto acids, which have been demonstrated to be components 

 of bile, include 3a-hydroxy-7-ketocholanic acid in guinea pig bile, 418 

 3,12-dihydroxy-7-ketocholanic acid 419 and 7,12-dihydroxy-3-ketocholanic 

 acid 419 ; the last two acids are present in cow bile. 



The keto acids may be regarded as intermediates in the formation of the 

 polyhydroxy acids. Thus, on the one hand, it has been demonstrated 

 that the organism can reduce the carbonyl group of the bile acids to the 

 hydroxy 1 groups, 420,421 or vice versa.* 22 As a specific example, one may cite 

 the in vitro conversion of 3-hydroxy-7-ketocholanic acid to a mixture of 

 ursodesoxycholic and chenodesoxycholic acid reported by Miyazi. 423 On 

 the other hand, the keto acids may originate by oxidation of the poly- 

 hydroxy acids. Hoehn, Schmidt, and Hughes 424 have shown that cholic 

 acid (3,7,12-trihydroxycholanic acid) gives rise to a monoketo and a diketo 

 acid during bacterial oxidation by the non-pathogenic intestinal bacterium, 

 Alealigenes faecalis (Bacterium fecalis alcaligenes) , to triketocholanic acid. 

 The acids which were found are 3,12-dihydroxy-7-ketocholanic acid and 

 3-hydroxy-7,12-diketocholanic acid. Oxidation takes place in the same 

 order when it is brought about by chromic acid. 3,12-Dihydroxy-7-keto- 

 cholanic acid has also been isolated from the bile of the reticulated python 

 (Python reticulatus) or boa of Indo-China by Kuroda and Arata 425 ; they 

 consider it to be an intermediate metabolite between cholic and desoxy- 

 cholic acid. 



Lithocholic acid (Or. \l9os, stone) is another bile acid reported by a 

 number of workers. Hans Fischer 426 first isolated it in 1911 from a gall- 

 stone obtained from an ox, while Schenck 427 more recently reported its 

 presence in a stone obtained from the gall bladder of a hog. Its presence 

 has also been reported in ox bile, 428 as well as in minute amounts in human 



417 H. Wieland and S. Kishi, Z. physiol. Chen., 214, 47-58 (1933). 

 418 1. Imai, Z. physiol. Chem., 248, 05-68 (1937). 



419 G. A. D. Haslewood, Biochem. J., 40, 52-54 (1946). 



420 K. Yamasaki and K. Kyogoku, Z. physiol. Chem., 233, 29-35 (1935). 



421 K. Yamasaki and K. Kyogoku, Z. physiol. Chem., 235, 43-46 (1935). 



422 T. Fukui, J. Biochem. (japan), 25, 61-69 (1937). 



423 S. Miyazi, Z. physiol. Chem., 250, 31-33 (1937). 



424 W. M. Hoehn, L. H. Schmidt, and H. B. Hughes, /. Biol. Chem., 152, 59-66 

 (1944). 



426 M. Kuroda and H. Arata, ./. Bio'chem. (Japan), 3.9, 225-226 (1952). 



426 H. Fischer, Z. physiol. Chem., 73, 204-239 (1911). 



427 M. Schenck, Z. physiol. Chem., 256, 159-168 (1938). 



428 H. Wieland and I>. Weyland, Z. physiol. Chan., 110, 123-142 (1920). 



