MISCELLANEOUS NITROGEN AND SULFUR COMPOUNDS 



291 



CH^CHoNHo 



CHgCHgNHg 



tryptamine 



serotonin 



Both of these compounds are widely distributed in plants, although usually in small amounts 

 (48-51). Tryptamine acts as a pressor amine (q. v. ) whereas serotonin produces effects 

 on the central nervous system. Methylated derivatives of serotonin are responsible for 

 the psychic effects produced by certain hallucinogenic mushrooms. These amines may 

 be purified and partially identified by the same types of methods described previously for 

 other amines. On paper chromatograms they may be detected by Ehrlich's reagent ( a 

 nearly saturated solution of dimethylaminobenzaldehyde in 12 N hydrochloric acid) which 

 gives blue colors with indole derivatives. There is little question regarding the biosyn- 

 thesis of these amines from tryptophan. The 5-hydroxy group of serotonin is probably 

 introduced into the tryptophan molecule before it is decarboxylated. 



In certain plants, especially Brassica spp. ascorbic acid occurs in a bound form 

 known as ascorbigen which is equal to ascorbic acid in nutritional value but does not react 

 in the usual chemical tests for ascorbic acid. Ascorbigen is an indole derivative of as- 

 corbic acid whose structure is not fully established but probably something like (52, 53): 



It seems probable that the precursor of the indole moiety of ascorbigen is the mustard oil 

 glucoside, glucobrassicin which is hydrolyzed by the action of myrosinase to form glucose, 

 S04=, SCN", and 3(j3-indolyl)-2-hydroxypropanal. The last compound immediately reacts 

 with ascorbic acid to form ascorbigen (54). 



The dye indigo is no longer of any commercial importance but is interesting as an 

 unusual natural indole compound. Indigo itself, however, does not occur in plants. 

 Leaves of certain species of the genus Indigo/era contain a glucoside indican which is first 

 hydrolyzed to the aglycone indoxyl by crushing the plant in water so that /3-glucosidases 

 can act. When air is passed through alkaline solutions of indoxyl, it is oxidized to the 

 blue dye indigotin. These reactions are as follows: 



0-&LUCOSE 



indican 



indoxyl 



indigotin 



