84 Fawcett, Wain, and Wightman 



From the quantities of acids detected on these chiomatograms, as 

 revealed by their spot size and intensity of color, it is apparent that 

 the members of this homologous series of amides vary in their suscep- 

 tibility to hydrolase action in wheat and pea tissues. The results in- 

 dicate that the differences observed are related to the distance be- 

 tween the ring system and the terminal amide group. "When these 

 are directly attached to each other, as in 3-indolecarbonamide, only 

 slight production of the corresponding carboxylic acid occurred, 

 whereas when a comparatively long side-chain separates the amide 

 group from the indole ring, as for example in S-(indole-3-)valeramide, 

 hydrolysis of -CONHo > -COOH readily occurred. 



Methyl Esters of co-(indole-3-)alkanecarboxylic Acids 



The pattern of biological activity shown by this homologous se- 

 ries of esters is similar to that already observed with the corresponding 

 acids and carbonamides. All members of the series, except methyl 

 indole-3-carboxylate, showed high growth-promoting activity in the 

 three tests employed (Table 2). The activity of the acetate and the 

 higher homologues is consistent with their probable conversion within 

 the test tissue to the corresponding carboxylic acid which is followed, 

 in the case of the butyrate and valerate, by (3-oxidation of this acid 

 to yield respectively indole-3-acetic or (3-(indole-3-)propionic acids. 

 The chromatograms (Figure 5) and the bioassay results (Figure 6) 

 obtained from metabolism experiments show clear evidence for this 

 type of degradation in wheat and pea tissues. Furthermore, the 

 chromatographic results indicate that methyl indole-3-carboxylate is 

 also hydrolyzed to the corresponding carboxylic acid in both these 

 tissues. 



The results from pea metabolism experiments again pro\ide evi- 

 dence for the formation of aspartic acid derivatives in this tissue. For 

 example, in extracts of the metabolized acetate, a large blue spot was 

 obtained at Rf 0.05 which was chromatographically identical with 

 authentic indole-3-acetylaspartic acid. Other substances produced in 

 metabolism experiments with this series of esters include the green- 

 ish-orange compound at Rf 0.25 which appeared in extracts of both 

 wheat and pea-treated propionate and valerate and also indole-3-car- 

 boxylic acid, which occurred not only on the chroma togram from the 

 treated carboxylate, but was also apparent in slight (]uaiititics in ex- 

 tracts from metabolized indole-3-acetate. 



The chromatographic results (Figure 5) obiainctl with these esters 



indicate that conversion of -COOCH3 > -COOH occurs more 



readily as the series is ascended. When the side-chain is short, only 

 a small amount of the corresponding carboxylic acid is produced. 



