TRIGLYCERIDES AND FATTY ACIDS 89 



After the administration of the triglyceride of nonanoic acid, azelaic 

 acid (HOOC-(CH2)7-COOH) and pimelic acid (HOOC-(CH2)5-COOH) 

 were identified in the urine. However, Verkade and van der Lee™ were 

 unable to demonstrate the excretion of dicarboxylic acids after the ingestion 

 of triglycerides of the higher fatty acids. 



The occurrence of a diaciduria is beUeved by Verkade^^ to be related to 

 carbohydrate metabolism. Whereas the concomitant metabolism of 

 carbohydrate is known to suppress ketonuria, Verkade and co-workers^^'^^ 

 found that the excretion of dicarboxylic acids by man, after the ingestion 

 of triundecylin, is augmented by the ingestion of carbohydrate. It is 

 suggested that, during fasting, a diaciduria does not occur; this is con- 

 sidered to be a "pathological fact,"^^ inasmuch as in the absence of carbo- 

 hydrate utilization "the classical w^ay of degradation of the saturated fatty 

 acids (unilateral jS-oxidation) is promoted at the expense of the w'ay of 



degradation by co-oxidation, with subsequent bilateral oxidation." 



More information is needed before one can understand the relationship of 

 diaciduria to carbohydrate metabolism.''- ■'^^ 



Flaschentrager and co-workers" "'''' confirmed the fact that the Cg to Cu 

 acids give rise to dicarboxylic acids. How^ever, it was recorded that the 

 proportion of fatty acids undergoing co-oxidation is very small (usually 

 0.1-1.0%), although in one instance the quantity excreted amounted to 

 5.8% of that ingested.''^ However, Flaschentrager et at. are of the opinion 

 that the importance of co-oxidation is minimal. Emmrich and Nebe^^ 

 noted that the feeding of fatty acids ha\'ing an uneven number of carbon 

 atoms to man and to dogs resulted in the excretion of small amounts of 

 pimelic acid, while the administration of hydrogenated coconut oil was 

 followed by the excretion of sebacic acid. Moreover, Bernhard^^ con- 

 cluded that co-oxidation is not a step in the normal catabolism of fatty 

 acids. This opinion is based upon the fact that, although succmic acid is 

 metabohzed w^hen fed to dogs or rats, adipic (Ce), suberic (Cg), sebacic 

 (Cio), and higher fatty acids (identified by labeling with deuterium) are 

 not metabolized to any appreciable extent. 



70 p. E. Verkade and J. van der Lee, Z. physiol. Chem., 225, 230-244 (1934). 



" P. E. Verkade, J. van der Lee, and M. Elzas, Biochim. et Biophys. Acta, 2, 38-56 

 (1948). 



" B. Flaschentrager and K. Bernhard, Helv. Chim. Acta, 18, 962-972 (1935). 



'3 B. Flaschentrager, K. Bernhard, C. Lowenberg, and M. Schlapfer, Z. physiol. 

 Chem., 225, 157-167 (1934). 



'^ B. Flaschentrager and K. Bernhard, Z. physiol. Chem., 238, 221-232 (1936). 



'5 R. Emmrich and E. Nebe, Z. physiol. Chem., 266, 174-182 (1940). 



'« K. Bernhard, Helv. Chim. Acta, 24, 1412-1425 (1941). 



