Chapter 14 



MISCELLANEOUS NITROGEN 



AND SULFUR COMPOUNDS 



The compounds treated in this chapter have a wide diversity of chemical and func- 

 tional characteristics. Their biogenetic interrelationships are also for the most part 

 obscure. However, in the absence of metabolic evidence, it seems likely that many of 

 the simpler nitrogen and sulfur compounds found in plants are derived by common types 

 of reaction schemes from the amino acids. By extension, plausible pathways can be sug- 

 gested leading from the amino acids to more complex compounds of this group. The 

 plausibility of such pathways has justified the organization of this chapter; but as direct 

 evidence becomes available, considerable revision may be necessary. Because of the 

 diversity of compounds covered, each section of this chapter is independent of the others 

 as regards characterization, isolation and metabolic pathways. 



AMINES 



It is not generally realized how widespread simple amines are in higher plants al- 

 though they are well-known as metabolic products of microorganisms. A survey of 220 

 species of flowering plants and mosses by Kamienski (1) revealed amines in a large num- 

 ber of them. Most widespread was isopentyl amine: 



C^3 

 CH3 



CHCHoCHoNH^ 



This occurred in 75 of the species examined. Twenty-five species had methylamine and 

 19 trimethylamine. Strangely, only one had dimethylamine. The chemistry of simple 

 amines is well described in general textbooks of organic chemistry and will not be dis- 

 cussed in any detail here. The standard reference on natural amines is the book of 

 Guggenheim cited under "General References". There is no sharp dividing line between 

 amines and alkaloids. This ambiguity becomes particularly evident with the more com- 

 plex amines such as histamine which might well be called an alkaloid except that it was 

 first found in animals and does not occur at a high concentration in plants. Several dis- 

 tinctions have been made to separate simple amines from alkaloids, but none is completely 

 satisfactory --e. g. : 



1. Alkaloids must have nitrogen in a heterocyclic ring. 



2. Alkaloids are more soluble in organic solvents like chloroform, while simple 

 amines are more soluble in water. 



The distinction made here, based on biogenesis, is that a simple amine has its complete 

 carbon skeleton (except for N -methyl groups) derived from a single precursor, normally 

 an amino acid. In the formation of alkaloids carbon--carbon and carbon-nitrogen con- 



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