CHAPTER 20 - β-Carbolines and Indole Alkylamines

Abstract

Publisher Summary The simplest secondary metabolites derived from tryptophan are indole alkylamines and β-carboline alkaloids. The indole alkylamines are substituted tryptamines. This chapter reviews the biosynthesis, metabolism, and taxonomic distribution of β-carbolines and indole alkylamines. Of the many plants known to produce and accumulate β-carboline alkaloids, only reports on cell cultures of Peganum harmala deal with these secondary metabolites. Rapidly growing suspension cultures contain no or low levels of β-carbolines. Media variation or the development of induction production media stimulates secondary product formation in cultured cells. Formation of secondary metabolites can be induced by biotic and abiotic elicitors. Screenings with media and cell extracts of known phytopathogenic and newly isolated microorganisms show that a great number of cell extracts or culture supernatants are able to induce serotonin and even β-carboline alkaloid formation. Increased levels of serotonin and β-carbolines can only be achieved at growth-inhibitory concentrations of the elicitors. The biosynthesis of serotonin in higher plants starts with the decarboxylation of tryptophan followed by 5-hydroxylation.