98 III. OXIDATION AND METABOLISM 



the mine. Moreover, the formation of nonanoic acid probably does not 

 occur, inasmuch as it would be expected to form azelaic acid as the result of 

 co-oxidation, and this has not been observed. Verkade and van der Lee'-'^-^^^ 

 reported similar negative results with erucic acid, insofar, as the non-ap- 

 pearance of nonanoic acid is concerned. In addition, Deuel et al}^ proved 

 that ethyl oleate gives rise to the same proportion of ketone bodies as does 

 stearic acid. This would preclude the splitting of this acid at the 9,10-bond. 

 Bernhard and Gloor^" likewise postulate that man and dog cannot oxidize 

 oleic acid at the double bond, thus facilitating the formation of azelaic acid. 

 It was fomid that when healthy subjects were given labeled D-azelaic acid, 

 the latter was excreted in michanged form, without variation in the original 

 isotope content. This would not be the case if the dicarboxylic acid were 

 an intermediate in oleic acid oxidation. Moreover, oleyl alcohol was oxi- 

 dized to the acid by the dog, rather than changed to azelaic acid. It was 

 likewise shown that, when /3-oxidation was inhibited by blocking the car- 

 boxyl group (formation of diethyl amide), co-oxidation resulted, rather than 

 a 9,10-splitting. In the case of N-butylamide oleic acid and anihd oleic 

 acid, no metabolic products whatsoever could be isolated from the urine. 

 On the other hand, 9,10-dihydroxystearic acid and 9,10-diketostearic acid, 

 when fed to dogs, were found to be oxidized to azelaic acid. 



Breusch^ is of the opinion that dehydrogenation in the 9,10-position is 

 probably not involved in the enzymic degradation of fatty acids. This de- 

 hydrogenation is regarded as a mechanism for the control of the physical 

 consistency of the body fats. It is suggested that dehydrogenation may 

 have the fmiction of rendering the fatty acids more liquid and diffusible, 

 and therefore more readily absorbable; sodium oleate is diffused with less 

 difficulty than is sodium stearate. The presence of unsaturated fatty acids 

 renders fats more digestible in the presence of high concentrations of dietary 

 calcium than in the case of more highly saturated fats.'-^ 



c'. Oxidation of 9,10-Unsaturated Fatty Acids with Triple Bonds: In 

 contradistinction to the fact that the doubly-bonded fatty acids are not 

 split at their unsaturated linkages, compounds possessing triple bonds are 

 readily decomposed at the site of their unsaturation. Thus, Bernhard and 

 Gloori24 reported that stearolic acid (CH3-(CH2)7-CHi C-(CH2)7-COOH), 

 stearoyl alcohol (CH3-(CH2)7-C: C-(CH2)7-CH20H), behenolic acid (CH3- 

 (CH2)7-C:C-(CH2)irC00H), and undecynoic acid (CHg-Ci C(CH2)7- 



122 K. Bernhard and U. Gloor, Helv. Chim. Acta, 35, 608-616 (1952). 

 1" A. L. S. Cheng, M. G. Morehouse, and H. J. Deuel, Jr., J. Nutrition, 37, 237-250 

 (1949). 



124 K. Bernhard and U. Gloor, Hetv. Chim. Acta, 36, 296-299 (1953). 



