Tryptophane Metabolism I. the Production of Kynurenic Acid from Tryptophane Derivatives* by Clarence P. Berg

Recent work (Berg, Rose, and Marvel, 1929-30) has shown that the essential amino acid, tryptophane, may be rendered unfit for supporting growth, either by benzoylation or by condensation with formaldehyde. The formaldehyde condensation product has been employed also by Jackson (1929) with a similar result. On the other hand, neither esterification with ethyl alcohol nor acetylation caused any detectable decrease in its growth-promoting ability. Although the ethyl ester hydrochloride used was shown to be very readily split by enzyme extracts, the acetyl derivative appeared to undergo cleavage only very slowly and incompletely. Inasmuch as tryptophane undergoes a series of react,ions in certain animal organisms by means of which it is converted into the quinoline derivative, kynurenic acid (Ellinger, 1904), it seemed of interest to employ the output of the latter product in the urine, following the administration of the tryptophane derivatives mentioned above, as a means of obtaining evidence regarding their cleavage in vivo. If the derivative in question should undergo enzymolysis either in the alimentary tract or in the body proper, the tryptophane liberated would cause an increase in urinary kynurenic acid elimination. For the purpose of demonstrating the production of kynurenic acid after tryptophane administration, the dog and the rabbit are