Planta Med 1991; 57: S85-S92
DOI: 10.1055/s-2006-960234
Alkaloids in Mammals

© Georg Thieme Verlag Stuttgart · New York

β-Carbolines and Tetrahydroisoquinolines: Detection and Function in Mammals

Hans Rommelspacher, Torsten May, Rudy Susilo
  • Department of Neuropsychopharmacology, Free University, Ulmenallee 30, D-1000 Berlin 19, Federal Republic of Germany
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Publication History

Publication Date:
05 January 2007 (online)


β-Carbolines occur in man and rat. The concentration in various tissues is about 100 to 1000 times lower than that of classical neurotransmitters. Administration of β-carbolines in animals induces overlapping but not identical activity profiles. The molecular modes of action differ. For example, harman (1-methyl-β-carboline) acts as an endogenous inhibitor of monoamine oxidase [E.C.], subtype A, whereas norharman (β-carboline) probably acts by stimulation of a specific β-carboline receptor which is different from the benzodiazepine-GABA receptor complex. There is substantial evidence that tetrahydroisoquinolines occur under physiological conditions as well. Whether tetrahydropapaveroline serves as a precursor of morphinanes in mammals, as has been found in opium poppies, remains to be elucidated.