TRIGLYCERIDES AND FATTY ACIDS 97 



According to Appel, Bohm, Keil, and Schiller,"^ even the unsaturated 

 acids having thirteen, fifteen, or seventeen carbons, which occur in the fat 

 depots after the feeding of synthetic fats with an odd number of carbon 

 atoms, have their first double bond at the 9,10-position. Although some of 

 the plant oils contain the double bond in another position, Millican and 

 Brown^^"* report that a majority have their first double bond in this 9,10- 

 location. Closely allied hydroxy-compounds with hydroxyl groups in the 

 9,10-position include aleuretic acid, CH20H.(CH2)5.CHOH.CHOH.(CH2)7.- 

 COOH, found in shellac, ^ '*""'' and 9,10-dihydroxystearic acid, present in 

 castor oil."^~^'^ 



b'. 9,10-Dehydrogenation as a Normal Pathway of Metabolism: Ver- 

 kade and van der J^QQ^^.uo.m observed that appreciable amounts of sebacic 

 acid were excreted by healthy men after triundecylin had been adminis- 

 tered. It is suggested that an intermediate unsaturated compound, namely 

 10-undecenoic acid (CH2:CH.(CH2)8.COOH), is formed presumably from 

 undecanoic acid, which splits at the double bond to yield sebacic acid. In 

 fact, when triundecylenin (containing 10:11 unsaturated imdecenoic acid) , 

 was fed, sebacic acid was actually obtained in the urine. It was therefore 

 suggested that the double bond may be a point of attack for the splitting of 

 the fatty acids and the subsequent formation of dicarboxylic acids. 



On the other hand, if oxidation of the fatty acids were to first mvolve de- 

 hydrogenation at the 9,10-position, with the resultant splitting of the chain, 

 one might expect that oleic acid would split to yield azelaic and nonanoic 

 acids as follows : 



CH3(CH2)7-CH:CH(CH2)7COOH > 



Oleic acid 



HOOC(CH2)7-COOH + CH3(CH.2)7-COOH 

 Azelaic acid Nonanoic acid 



However, when triolein was fed in large amounts to man in the form of olive 

 oil, Verkade and van der Lee^-"'^-^ were miable to isolate azelaic acid from 



'" H. Appel, H. Bohm, W. Keil, and G. Schiller, Z. physiol. Chem., 274, 186-205 

 (1942); :g5^, 220-244 (1947). 



11* R. C. Millican and J. B. Brown, /. Biol. Chem., 154, 437-450 (1934). 



i'5 W. Nagel, fie/-., 60B, 605-609 a927). 



lis H. Raudnitz, H. Schindler, and F. Petru, Ber., 68, 1675-1676 (1935). 



1" A. Tschirch, Schweiz. Apoth. Z., 60, 609-611 (1922). 



118 A. Eibner and E. Munzing, Chem. Umschau, 32, 166-176 (1925); Chem. Abst., 19, 

 ;^027 (1925). 



ii« G. King, J. Chem. Soc, 1942, 387-391. 



1^ P. E. Verkade and J. van der Lee, Proc. Acad. Sci. Amsterdam, Sect. Sci., 37, No. 9, 

 590-597 (1934). 



"1 P. E. Verkade and J. van der Lee, Z. physiol. Chem., 230, 207-215 (1934). 



