579 



In the intestinal contents have been found a number of substances that are 

 undoubtedly derived from these aromatic radicals. They are (1) phenol, 



yon 



which is formed in small quantities, presumably from tyrosine, as also is the 

 closely related (2) paracresol, 



and also (3) ■para-oxyphenyl acetic acid, 



HO <^N CH2— COOH 

 and (4) para-oxyphenyl-propionic acid. 



}IO^~y CH2— CH2— COOH 



From the tryptophane are formed numerous important substances, as follows: 



NH2 



/-\ I 



< >— C— CH2— CH— COOH 



^ \ 

 \^CH 



NH 



(tryptophane) 



readily yields, through splitting off the NH2 group and addition of H, indole 

 propionic acid (formerly incorrectly called skatole acetic acid), which is 



CH2— CH2— COOH 



CH 



1 / 

 NH 



and from which in turn may rcadilj' be formed indole acetic acid (erroneously called 

 skatole carboxylic acid), which is 



CH2— COOH 



\ /' 



NH 



\ 

 CH 



/ 



