ON THE EXCRETION OF KYNURENIC ACID.* 



BT LAFAYETTE B. MENDEL AKD HOLMES C. JACKSON. 



ALTHOUGH it is nearly half a century since Liebig discovered 

 kynurenic acid in the urine of the dog, and this compound 

 has long been assigned the constitution of an oxyquinoline- 

 carboxylic acid,f there is much investigation yet demanded 

 regarding its antecedents and origin in the metabolic processes 

 of the body. The occurrence of kynurenic acid in the animal 

 organism is interesting, because with the exception of a- 

 methylquinoline recently isolated by Aldrich and Jones J from 

 the anal secretion of Mephitis mephitica (common American 

 skunk), it is, so far as we recall, the only quinoline compound 

 discovered in connection with the animal body. Furthermore, 

 the study of kynurenic acid production is important, because 

 of the light which it promises to throw upon the transforma- 

 tions going on in the system, upon the constitution of the 

 proteids from which the compound is derived, and possibly 

 upon the physiological behavior of compounds like many of 

 the alkaloids related to quinoline derivatives. 



The early investigations on kynurenic acid can scarcely 

 demand detailed consideration at present, since in the absence 

 of satisfactory analytical methods the separation of uric acid 

 (and possibly other substances) from the acid investigated was 



* Reprinted from the American Journal of Physiology, vol. ii. A pre- 

 liminary account of some of the experiments described in this paper was 

 presented at a meeting of the American Physiological Society, December 28, 

 1897. 



t Schmiedeberg and Schultzen, Ann. Chem. Pharm., 1872, clxiv, p. 155. 

 Kretschy, Berichte d. deutsch. chem. Gesell., 1879, xii, p. 1673 ; Monatshef te 

 fur Chemie, 1881, ii, p. 57. 



t Aldrich and Jones, Journal of Experimental Medicine, 1897, ii, p. 439. 



