Skatolecarboxylic acid

The formation of indole by the putrefaction of proteins was observed by Kiihne and by Nencki in 1874, that of skatole by Briefer in 1877, of skatolecarboxylic acid by E. and H. Salkowski in 1880, and of skatole-acetic acid by Nencki in 1889. Nencki regarded these substances as originating from a skatoleaminoacetic add in the protein in a manner similar to that by which phenol, cresol, oxyphenylacetic acid and oxyphenylpropionic acid arose from tyrosine, namely —... 

The constitution of indole and skatole had been proved by synthesis, but that of the other two compounds had not been determined, and Nencki s formulae for them were accepted. Investigations by Ellinger and Gentzen in 1903, who found that in the large intestine indole was formed in large amounts from tryptophane, but skatole only in small amounts, and that skatole only gave traces of indole under the same conditions led Ellinger to doubt the accuracy of Nencki s formulae for skatoleacetic and skatolecarboxylic acids, more especially as Wislicenus and Arnold s skatolecarboxylic acid, which was synthesised from pro-pionyl formic acid phenylhydrazone had the formula... 

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