Clnomatographic Investigations of Indole Compounds 89 



sion of -CHoCN > -COOH and is considered an example of the 



a-oxidation of nitriles, might be expected to occur with all the higher 

 homologues of the nitrile series when metabolized in wheat tissue. In 

 each case, the -CHoCN grouping would be converted to -COOH and 

 the resulting acid would then be subjected to (3-oxidation. The chro- 

 matographic results (Figure 7) support this possibility and indicate 

 that the higher indole nitriles are metabolized in wheat not only by 

 a sequence involving initial hydrolysis of the nitrile to the corre- 

 sponding carboxylic acid and subsequent p-oxidation, but also by a 

 sequence involving an initial a-oxidation of the nitrile to the next 

 lower carboxylic acid which then undergoes [5-oxidation. Evidence 

 for these two distinct pathways is most clearly revealed on chromato- 

 grams of the metabolized capro- and heptano-nitriles. Thus, for ex- 

 ample, the extract of wheat-treated capronitrile yielded spots at Rf 

 0.26 and 0.40 which were identified as the acetic and butyric acids 

 respectively and presumably arose via the hydrolysis followed by (3- 

 oxidation pathway. Distinct blue spots were also evident on the chro- 

 matogram at Rf 0.32 and 0.49, and from their Rf value, color reac- 

 tions, and biological activity the compounds were identified as the 

 propionic and valeric acids, respectively. The latter acid could arise 

 from a-oxidation of the capronitrile, and the propionic acid would 

 then be produced by |3-oxidation. A similar explanation could ac- 

 count for the degradation products observed on the chromatogram 

 obtained from the metabolized heptanonitrile. 



In the extracts of both of these higher nitriles a further compound 

 was apparent which from its Rf value (0.20), characteristic color re- 

 actions, and absence of biological activity was identified as indole-3- 

 carboxylic acid. Although this acid is the logical end product of the 



heptanoic acid > valeric acid > propionic acid (3-oxidation 



sequence, earlier metabolism experiments using the authentic acids 

 produced no evidence that this final stage occurred in wheat tissue 

 (Figure 1). In the present experiments, however, in addition to its 

 appearance in appreciable quantities during the metabolism of the 

 capro- and heptano-nitriles, a small amount of indole-3-carboxylic 

 acid was also observed on the chromatogram of the metabolized 

 valeronitrile. Hence there is a possibility that in wheat tissue these 

 higher nitriles are degraded by another mechanism which involves 

 oxidation of the methylene group adjacent to the indole ring. This 

 type of degradation reaction may be referred to as co-oxidation. 



The following are the results obtained with this series of nitriles 

 in the pea segment and pea curvature tests (Table 2). Only indole-3- 

 acetonitrile and l;-(indole-3-)heptanonitrile were active, suggesting that 

 hydrolysis of -CN > -COOH does not readily occur with all mem- 



