Beta carbolines

β-carboline as the main body of the compounds

β-carbolines are substances that act as inverse agonists and bind to the benzodiazepine binding site of GABA receptors and thus reduce the likelihood of this ligand-controlled channel opening due to a reduced affinity of γ-aminobutyric acid ( GABA ). In addition, representatives of this group can also bring about a reversible inhibition of monoamine oxidase . Both effects lead to a psychological influence.

Natural occurrence

Plants with these alkaloids have been found especially in South America . In Banisteriopsis caapi , Vestia foetida , and in some types of wind plants to find forms of β-carbolines. The rue is a plant with beta-carboline content that occurs worldwide.

Mode of action

The reduced likelihood of opening causes a reduced flow of chloride ions through the channel. This leads to a lower inhibition of the transmission or an increase in the transmission of nerve impulses in the central nervous system , since here the GABA-mediated inhibition of synapses is one of the most important control mechanisms. Depending on the localization of the correspondingly influenced canal, this leads to increased excitation. In particular, it can trigger anxiety.

Just like the antagonists (benzodiazepines) to which the β-carbolines behave as competitive antagonists , the inverse agonism can be reversed by flumazenil , i.e. the pure antagonist of the benzodiazepine binding site of the GABA receptor.

Due to the MAO inhibition , interactions with foods containing tyrosine and histamine , a variety of drugs ( alcohol , ecstasy , opiates, etc.) as well as medications ( serotonin reuptake inhibitors , DXM, etc.) can lead to a fatal serotonin syndrome .

See also : Rue

Substances

The β-carbolines include u. a. (incomplete list):

• Harman alkaloids with their representatives:
  • Harmine
  • Harmaline
  • Tetrahydroharmine
  • Harmalol
• Tryptoline (tetrahydro-β-carboline)
• Pinolin (6-methoxy-tetrahydro-β-carboline)
• β-Carboline-3-carboxylic acid ethyl ester (β-CCE)

Sources and individual references

1. ^ ^{A b} Klaus Aktories, Ulrich Förstermann, Franz Hofmann, Klaus Starke: General and special pharmacology and toxicology , 10th edition, Elsevier, Urban & Fischer, Munich; Jena 2009, ISBN 978-3-437-42522-6 .
2. ^ Edward J. Massaro: Handbook of Neurotoxicology . Humana Press, 2002, ISBN 0-89603-796-7 , p. 237.