24 II. CHEMISTRY OF FATTY ACIDS AND GLYCEKOfi 



Elaeostearic acid and oxygen react with an increased acti^dty as com- 

 pared with the non-conjugated acids and oxygen. On the other hand, the 

 addition of halogens is retarded by conjugation, and the iodine numbers 

 obtained with elaeostearic acid are considerably below the theoretical 

 value. Because of its ready oxidation, elaeostearic acid is highly prized 

 as a drying oil. Tung oil finds wide application in rapidly drying varnishes 

 and enamels, which are also alkali- and acid-resistant. In addition it has 

 the property of being easily polymerized and of forming gels on heating. 



d. Arachidonic Acid. Arachidonic acid is one of the most interesting 

 of the polyethenoid acids. It has four double bonds in non-conjugated 

 positions. Smedley-Macliean and associates, ^^-^^ as well as Mowry et al.^^ 

 have shown it to be 5,8,11,14-eicosatetraenoic acid, CH3(CH2)4CH:CH- 

 CH2CH:CHCH2CH:CHCH2CH:CH(CH2)3COOH. The name was sug- 

 gested by Lewkowitsch.^^ 



Arachidonic acid is present in animal but not in vegetable oils. It forms 

 a part of liver, "••'^ egg,^^ and brain lecithins,^^ as well as brain cephalin.®'-''^ 

 Wesson^^ has reported the presence of arachidonic acid in tissues and liver 

 from rats, and in organs from dogs, including liver, pancreas, kidney, lung, 

 spleen, and lymph-gland, as well as in muscle fats. Tliis acid is also 

 present in amounts as high as 2.1% in pig depot fat,^--'''* and it has been 

 found in ox,^^ duck, goose, chicken, '^^ and human depot fat.'^^"''^ It has 

 likewise been reported as a component of butter fat.'^^ Shinowara and 

 Brown*' have suggested that the arachidonic acid present in the phos- 

 phatides of beef adrenal tissue is C,10,14,]8-eicosatetraenoic acid; it com- 

 prises 20% of the total phosphatides. The latter authors stated that these 

 phospholipids are the best starting material for the preparation of ara- 

 chidonic acid. However, it should be noted that Arcus and Smedley- 



6^ D. E. Dolby, L. C. A. Nunn, and I. iimed\cy-MacJ.oan, Biochem. J., 34, 1422-1426 

 (1940). 



6s D. T. Mowry, W. R. Erode, and J. B. Brown, ./. Biol. Chern., 142, 671-678 (1942). 



** J. Lewkowitsch, Chemical Technology and Analysis of Oils, Fats, and Waxes, Vol. I, 

 6th ed., Macmillan, London (1921), pp. 28, 214, 215, 237, 239. 



" R. A. Snider and W. R. Bloor, J. Biol. Chem., 90, 555-573 (1932). 



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

 (1922). 



«^ P. A. Levene and L P. Rolf, ./. Biol. Chem., 51 507-513 (1922); 54, 91-98; 99-100 

 (1922); 67, 659-666 (1926). 



™ L. G. Wesson, J. Biol. Chem., 60 183-187 (1924). 



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



" A. Banks and T. P. Hilditch, Biochem. J., 26, 298-308 (1932). 



" H. K. Dean and T. P. Hilditch, Biochem. J., 27, 1950-1956 (1933). 



7" J. B. Brown and E. M. Deck, J. Am. Chem. Soc, 52, 1135-1138 (1930). 



'6 J. B. Brown and C. C. Sheldon, J. Am. Chem. Soc, 56, 2149-2151 (1934). 



'6 D. L. Cramer and J. B. Brown, J. Biol. Chem., 151, 427-438 (1943). 



" H. C. Eckstein, /. Biol. Chem., 64, 797-806 (1925). 



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



" A. W. Bosworth and E. W. Sisson, /. Biol. Chem., 107, 489-496 (1934). 



80 G. y. Shinowara and J. B. Brown, /. Biol Chem,, 134, 331-340 (1940). 



