BRANCHED-CHAIN ACIDS 



295 



Hildebrandt and dihydro-Hildebraiidt acids were eliminated in the urine. 

 The ()('.(;urience of w-oxidation is beheved to result from the hhidrance to 

 /3-oxidation by the branched- chain on the a- or /3-carbon, or from its pres- 

 ence in both positions. These reactions are illustrated below: 



CH3V 



C : CH • CHo • CHo ■ CH • CH. • COOH 



CH3 

 Rhodinic acid 



CH, 



\, 



ca/ 



CiCHCHoCHsCrCHCOOH 



CH3 

 Geranic acid 



CH3 

 CH, 



CH • CH, • CHo • CH • CH2 ■ COOH 



1 

 CH, 



Tetrahydrogeranic acid 



CH, 



\ 



HOOC/ 



C : CH ■ CH2 ■ CH2 • CH • CH2 • COOH 



CH, 

 Dihydro-Hildebrandt acid 



Hj 



CH2^ 

 HOOC^ 



CiCHCHjCHaCrCHCOOH 



CH3 

 Hildebrandt acid 



-^ Dihydro-Hildebrandt acid -f- 

 Hildebrandt acid 



The Formation of Dicarboxylic Acids by w-Oxidation after the Administration of 

 L-Rhodinic Acid, Geranic Acid, or Tetrahydrogeranic Acid, Based upon the Findings of 

 Hirohata et al.^ 



(3) ^-Phenyl- Suhstituted Acids 



When the phenyl group occurs on the /3-position, ;S-oxidation of the fatty 

 acid is like^vise hindered or entirely blocked; under such conditions, 00- 

 oxidation may also occur as an emergency method of disposing of these 

 fatty acids. ^"'^^ Stevens^^ also showed that, when a phenyl group is intro- 



' R. Hirohata, S. Yamasaki, T. Iseki, T. To, S. Iseda, and M. Shojima, /. Biochem. 

 (Japan), 38, 135-146 (1951). 



'" B. Flaschentrager, K. Bernhard, C. Lowenberg, and M. Schlapfer, Z. physiol. 

 Chem., 225, 157-167 (1934). 



11 R. Kuhn, F. Kohler, and L. Kohler, Z. physiol. Chem., 242, 171-197 (1936); 2^7, 

 197-219 (1937). 



1^ C. M. Stevens, /. Azlactones. II. Metabolism of Fatty Acids. Thesis, Univ. 

 Illinois, 1941; also cited by H. E. Carter, Biol. Symposia, 5, 47-63 (1941), p. 60. 



