Consequences of administration of indoleacetic acid 



assay of an aliquot of the brei, he extracted the reaction products from the 

 medium with chloroform. The chloroform extract was concentrated, applied 

 to paper, and an analysis of the nature of the product attempted by the 

 combined use o^ Rf, spray reagents, and the preparation of derivatives. 



Using the uopropanol-ammonia-water developer in a 10 : 1 : 1 ratio 

 and later in a 2 : 1 : 1 ratio. Dr. Manning was able to show the presence 

 of at least two principal products which accumulated concurrently with the 

 disappearance of lAA. These products moved with Rfh of 0-94 and 0-91, 

 and had a faint yellow colour before the application of any spray reagent. 

 Upon spraying with Ehrlich's reagent (1 per cent /^-dimethylaminobenz- 

 aldehyde in 1 X HCl), both spots immediately turned orange. ^Vith standing, 



C — COOH 



C — CH, COOH 



3-Indoleacetic acid 



3-lndolealdehyde 



4-Hydroxyquinoline 



o-Formamidoacetophenone 



Dcrformylation 





 II 



•C — CH3 



+HCOOH 

 '2 o-Aminoace1ophenone 



Figure 4. Four possible oxidation products of I A A, resulting from oxidation of either side-chain or ring. 



a' 

 NH, 



the Rf 0-94 spot developed red tinges, and finally became uniformly pink. 

 The spot at Rf 0-91 behaved similarly, finally becoming red. Both spots gave 

 a rose colour in 3-5 minutes with 1 per cent aqueous FeClg, which deepened 

 with time, assuming an especially deep colour at the Rf 0-94 spot. Since 

 3-indolealdehyde differs from both of the observed reaction products in Rf 

 and colour reactions, we have concluded that it is not a major product of the 

 oxidation (Manning and Galston, 1955). 



On the basis of analogy with the conversion of tryptophan to kynurenine 

 (Beadle, Mitchell, and Xyc, 1947), we had supposed that the indole ring of 

 lAA could be cleaved {Figure 4) to yield o-formamidoacetophenone (OFA), 

 or secondarily o-aminoacetophenone (OAA) or dihydroxyquinoline (DHQ). 

 Unfortunately, none of these compounds has properties which exactly match 

 the behaviour of either of the two vuiknowns, nor are they acted upon by the 

 enzyme to yield the authentic products. Nevertheless, the mobilities and 

 and colour reactions of OFA and OAA are close enough to the products to 

 warrant the assumption that they are in fact related to the products. The 

 main difference lies in their failure to give a proper colour with FeClg, which 



223 



