Protoalkaloids

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Structural formula of the protoalkaloid ephedrine

Protoalkaloids (word formation from the Greek proto - first and alkaloids ) are naturally occurring nitrogenous compounds which, in contrast to the alkaloids in the narrower sense and pseudoalkaloids, are characterized by the lack of a nitrogenous heterocycle . They are secondary metabolic products and are formed from amino acids through simple reactions such as decarboxylation or N- methylation . In addition, the term protoalkaloid is often restricted to simply constructed compounds, in particular biogenic amines , in order to distinguish the compounds from alkaloids in the narrower sense. Other definitions exclude vertebrate neurotransmitters .

Protoalkaloids are often used in metabolism as starting substances for the formation of more complex alkaloids. They are widespread and some substances in this group occur as breakdown products of amino acids in low concentrations in almost all living things. Therefore they are rarely suitable as characterizing ingredients in the botanical systematics .

The protoalkaloids include, for example, the ephedra alkaloid ephedrine , the peyotl alkaloid mescaline , the indole alkaloid gramin , the biogenic amines tryptamine and tyramine and betaines . Less strict definitions also include more complex compounds, such as colchicine and stephenandrine , in this group of substances.

literature

  • Robert Hegnauer: Chemotaxonomy of Plants: VOL 3: Dicotyledoneae . Birkhäuser, 1964, ISBN 978-3-7643-0166-8 .
  • Peter G Waterman: Alkaloid Chemosystematics . In: The Alkaloids: Chemistry and Biology . tape 50 , 1998, pp. 537-565 (English).