532 VI. OCCURRENCE OF LIPIDS IN THE ANIMAL 



Wagner 66 failed to confirm this fact. It is altogether possible that this 

 discrepancy may have been related to the diet of the two individuals 

 before death. 



(e) Elaeostearic Acid. Elaeostearic acid, 9,11,13-octadecatrienoic acid, 

 is a conjugated trienoic acid, present in high concentration in tung oil and 

 in other tropical plants. According to Burr et aZ., 67 purified a-elaeostearic 

 acid is ineffective as a source of essential fatty acids. Therefore it cannot 

 be converted to the corresponding non-conjugated trienoic acid, linolenic 

 acid, in vivo. If this were the case, it would cure essential fatty acid de- 

 ficiency, just as linolenic acid does. 



Miller and Burr 68 reported that a-elaeostearic acid may be deposited in 

 the tissues of rats. However, the acid rapidly undergoes a transformation 

 to dienoic acids. Cruickshank et al. 55 likewise demonstrated that elaeo- 

 stearic acid may be deposited in the tissue lipids of hens. Reiser 44 proved 

 that trienoic acids continue to be excreted in the egg yolks for as long as 

 twelve days after conjugated linolenic acid has been administered to hens 

 in 18 g. doses divided over a three-day period. Although the unsaturated 

 acids were present in both the neutral fat and the phospholipid fraction, 

 they were in a higher concentration in the latter. Moreover, when a- 

 elaeostearic acid in the form of tung oil was fed to laying hens in amounts as 

 high as 6 g., a slow rise was noted in the trienoic acid content of the egg- 

 yolk fat, which reached the maximum in five days. In these tests also, the 

 greater concentration of the unsaturated acids was noted in the phospho- 

 lipid fraction. 



(/) Arachidonic Acid. Arachidonic acid, 5,8,11,14-eicosatetraenoic acid, 

 is widely distributed in animal fats, but it does not occur in the plant king- 

 dom. It is present in the liver, 69,70 where it is the only highly unsaturated 

 acid, 71 and in the brain, in which case it has been shown to occur in both 

 the lecithin 72 and the cephalin 72,73 fractions. The wide distribution of this 

 acid in tissues has been demonstrated by Wesson, 74 who demonstrated its 

 occurrence in the liver of rats and in the liver, pancreas, kidney, lung, 

 spleen, lymph glands, and muscle fat of dogs. Brown 75 reported the 



66 O. Wagner, Biochem. Z., 174, 412-419 (1926). 



67 G. O. Burr, M. M. Burr, and E. S. Miller, J. Biol. Chem., 97, 1-9 (1932). 



6S E. S. Miller and G. O. Burr, Proc. Soc. Exptl. Biol. Med., 36, 726-729 (1937). 



69 R. H. Snider and W. R. Bloor, J. Biol. Chem., 99, 555-573 (1933). 



70 P. A. Levene and H. S. Simms, J. Biol. Chem., 48, 185-196 (1921); 51, 285-294 

 (1922). 



71 J. B. Brown, /. Biol. Chem., 80, 455-460 (1928). 



72 P. A. Levene and I. P. Rolf, J. Biol. Chem., 54, 91-98, 99-100 (1922). 



73 L. G. Wesson, /. Biol. Chem., 60, 183-187 (1924). 



74 L. G. Wesson, J. Biol. Chem., 65, 235-250 (1925). 

 76 J. B. Brown, J. Biol. Chem., 83, 777-782 (1929). 



