Nitrogen compounds plant productivity

The ease with which amines are extracted into aqueous acid, combined with their regeneration on treatment with base, makes it a simple matter to separate amines from other plant materials, and nitrogen-containing natural products were among the earliest organic compounds to be studied. Their basic... 

Sequestration of plant natural products by herbivorous insects is widespread. This is not surprising, since most insects are herbivorous and it is estimated that there are between two and six million species. While these sequestrators obviously exploit their alkaloid-rich host plants, such specialists represent a very minor component of the total herbivorous population. In essence, these nitrogenous compounds are highly effective deterrents for most of the herbivorous species with which they share their world. On the other hand, a brief discussion of some of the alkaloids and their specialist herbivores illustrates the versatiliity of these insects as exploiters of toxic compounds This alkaloidal treatment has been derived from the tables of Brown and Trigo10 and emphasizes... 

Returning to the question in the title of this section, capsaicin does not fall into any of the three classic types of nitrogen-bearing plant natural products, being neither a true alkaloid, a protoalkaloid, or a pseudoalkaloid. Capsaicin is oflimited distribution in Nature and shows pharmacological activity, but is non-basic, structurally unsophisticated, and not directly derived from an amino acidic precursor. On the other hand, the lack of attributes such as basicity, complexity, and an amino acidic pedigree can also be found in compounds commonly perceived as alkaloids. Thus, colchicine is neutral, ephedrine is structurally unsophisticated, and the nitrogen atom of the potato alkaloid solanine is not derived from an amino acid, but rather incorporated into as non-amino acidic framework by a transamination reaction. For the sake of clarity and consistency, it seems therefore convenient to adopt the modern definition of alkaloids, and consider capsaicin, as well as alkylamides such as piperine (18) and pellitorine (19), as such. 

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