188 



III. OXIDATION AND METABOLISM 



According to Clement and May/*- conjugated tetraenoic acid can be 

 hydrogenated to conjugated trienoic acid by the rat. 



Figure 3 represents some of the known interconversions of the several 

 polyunsaturated acids. For a further treatment of the physiology and 

 chemistry of the polyunsaturated acids, particularly those having biological 

 activity against the fat-deficiency syndrome, the reader is referred to a 

 recent review of Deuel and Reiser,^*^ as well as to Chapter VII of this 

 volume. 



e. The Metabolism of Polyunsaturated Acids as Related to the State of 

 Oxidation. One of the chief properties of the polyunsaturated acids is the 



Diene 



hen, chick, dog, rat, mouse ^ Tetraene' 



hen, chick 



Triene 



> Hexaene 



Fig. 3. The possible biologic interconversions of polyunsaturated fatty acids (supplied 



in text).8" 



readiness with which they enter into auto-oxidation. Several investigators 

 have studied the role of such oxidations in the normal metabolism of the 

 polyunsaturated acids. 



Dubouloz et al.^'^^ reported that peroxides of fatty acid esters formed 

 after the ingestion of ethyl oleate are gradually eliminated from the 

 gastrointestinal tract, and that no determinable quantities are deposited 

 in the tissues. Although small amounts of such compounds apparently do 

 occur in adipose tissue, the digestive origin was not proved. The action 

 of cold or of x-irradiation was later shown^*^ to result in the formation of 

 lipid peroxides in the skin of the rat. 



On the basis of in vitro studies, KunkeP*^ reported that d-cc-tocopherol 



«"G. Clement and P. May, /. Physiol. (Paris), 45, 79-83 (1953). 

 "3 H. J. Deuel, Jr., and R. Reiser, Vitamins and Hormones, 13, 29-70 (1955). 

 "^ P. Dubouloz, J. Fondarai, and C. Lagarde, Biochim. et Biophys. Acta, 3, 371-377 

 (1949). 



"6 P. Dubouloz and J. Dumas, Compt. rend., 234, 2575-2576 (1952). 

 "« H. O. Kunkel, Arch. Biochem., SO, 317-325 (1951). 



