DEMOLITION OF AROMATIC FATTY ACIDS. 781 



the w-tyrosine passes according to FLATOW 1 in part as ra-oxyphenyl 

 pyruvic acid in the urine. The keto-acids give also the same end products 

 as the corresponding amino-acids. Thus o-tyrosine, like o-oxyphenyl- 

 pyruvic acid, yields o-oxyphenylacetic acid (FLATOW) as end product; 

 the p-chlorphenylalanine and the p-chlorphenylpyruvic add pass into the 

 p-chlorphenylacetic acid, which is not the case with the oxyacid, the p-chlor- 

 phenyl-lactic acid (FRIEDMANN and MAASE 2 ) . This last-mentioned case is 

 an example of the more ready combustibility of the keto-acids as com- 

 pared to the oxy acids. Another such example is the p-oxy phenyl pyruvic 

 acid, which is in great part burned, while the p-oxyphenyl-lactic acid is 

 hardly burned at all (KOTAKE, SUWA). A correspondingly different 

 behavior is shown by these two acids in perfusion experiments with 

 the excised liver of the dog. The oxyphenylpyruvic acid, like tyrosine, 

 shows itself to be an acetone former while oxyphenyl-lactic acid, on 

 the contrary, does not (NEUBAUER and GROSS, E. ScHMiTz 3 ). The 

 ready combustibility of the keto-acids indicate that these acids and 

 not the oxyacids are the important intermediary cleavage products. 



In regard to the demolition of aromatic fatty acids, KNOOP 4 has found 

 that the acids with even carbon chains, such as phenyl butyric acid and 

 phenyl caproic acid, are converted into phenylacetic acid, which con- 

 jugates with glycocoll to form phenaceturic acid, while the acids with 

 uneven carbon chains, like phenylpropionic and phenylvaleric acid, 

 yield benzoic acid, which then is eliminated as hippuric acid. This 

 behavior is in close agreement with the generally accepted oxidation of 

 fatty at the /3-group, for which DAKIN has also given important support. 

 Thus DAKIN found after feeding phenylpropionic acid to cats, that 

 phenyl-@-oxypropionic acid, benzoylacetic acid and acetophenone, the latter 

 passing into benzoic acid or hippuric acid, were formed, which pre- 

 supposes an oxidation in the /3-position. According to the investigations 

 of DAKIN and FRIEDMANN 5 the conditions are still very complicated. 

 Certain of the processes are reversible, oxidations as well as reductions 

 occur, and a-0-unsaturated acids may also be formed as intermediary 

 products. DAKIN as well as FRIEDMANN have obtained cinnamic acid 

 as intermediary product in the demolition of phenylpropionic acid, and 



1 Neubauer, Deutsch. Arch. f. klin. Med., 95; Flatow, Zeitschr.f. physiol. Chem., 64. 



2 Flatow, 1. c.; Friedmann and Masse, Bioch. Zeitschr., 27. 



8 Kotake, Zeitschr. f. physiol. Chem., 69; Suwa, ibid., 72; Neubauer and Gross, 

 ibid., 67; Schmitz, Bioch. Zeitschr., 28. 



4 Hofmeister's Beitrage, 6, and Habilit.-Schrift, Freiburg, 1904. 



6 Dakin, Journ. of biol. Chem., 4, 5, 6, 8, and 9; Friedmann, see Med. Klinik, 

 No. 28, 1911, and Bioch. Zeitschr., 35. 



