PRODUCTS FROM NITROGENOUS COMPOUNDS 



89 



6. Carboxylic decomposition with the formation of a fatty acid 

 with one less carbon atom. 



R CH2 CH 2 COOH + SO = R 



COOH + CO 2 + H 2 O 



Some of these changes are often produced either within food or in 

 the alimentary canal and are of considerable clinical significance. 

 The most important of these are indol, skatol and the amins, the 

 simplest of which is trimethylamin. 



Indol and skatol are substances produced in the intestinal tract 

 from tryptophan chiefly by B. coli and B. proteus. They are also 

 formed in putrifying proteins and it is to indol and skatol that putri- 

 fying substances owe their intensely disagreeable odor. Indol 

 gives a rose color with nitrites in acid solution and this is used as a 

 method of identifying certain bacteria. The tryptophan is deam- 

 inized with the formation of indol propionic acid. This is oxidized 

 to indol-acetic acid. From this latter there is split off acetic acid 

 with the formation of indol. The reactions are as follows: 



CH 



HC 



HC 

 \ 



C N 

 H H 

 Tryptophan. 



CH 



CH CH NH 2 



/ I 



COOH 



HC 



C- 



II 

 C 



-CH 2 



HC 



\ 



C N 



H H 



Indol-propionic acid. 



CH 



CH CH 2 



I 

 COOH 



HC 



C- 



II 

 C 



-c- 



-CH 2 



HC C CH COOH 



\ /\ / 

 CH NH 



Indol-acetic acid. 



CH 



/" \ 

 HC C -CH 



I II II 



HC C CH 



\ /\ / 

 CH NH 



Indol. 



Often the bacteria split out carbon dioxid from the indol-acetic 

 acid with the formation of skatol : 



/ 



HC 



CH 



C- 



C 



-CH 2 



HC 



\ 



CH NH 



Indol-acetic acid. 



CH COOH 



CH 



/ \ 

 HC C- 



I II 



HC C 



-C CH 3 



II 

 CH 



CH NH 



Skatol. 



