beta-Carboline

β-Carboline

Names
IUPAC name 9H-β-carboline
Other names 9H-pyrido[3,4-b]indole
Identifiers
CAS Number	244-63-3 Y
ChEBI	CHEBI:109895 Y
ChEMBL	ChEMBL275224 Y
ChemSpider	58486 Y
IUPHAR/BPS	8222
Jmol 3D model	Interactive image
MeSH	norharman
PubChem	64961
InChI InChI=1S/C11H8N2/c1-2-4-10-8(3-1)9-5-6-12-7-11(9)13-10/h1-7,13H Y Key: AIFRHYZBTHREPW-UHFFFAOYSA-N Y InChI=1/C11H8N2/c1-2-4-10-8(3-1)9-5-6-12-7-11(9)13-10/h1-7,13H Key: AIFRHYZBTHREPW-UHFFFAOYAG
SMILES c2cncc3nc1ccccc1c23
Properties
Chemical formula	C11H8N2
Molar mass	168.20 g/mol
Vapor pressure	{{{value}}}
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

β-Carboline (9H-pyrido[3,4-b]indole), also known as norharmane, is a nitrogen containing heterocycle. It is also the prototype of a class of compounds known as β-carbolines.

Pharmacology

β-Carboline alkaloids are widespread in plants and animals, and frequently act as benzodiazepine inverse agonists. As components of the liana Banisteriopsis caapi, the β-carbolines harmine, harmaline, and tetrahydroharmine play a pivotal role in the pharmacology of the indigenous psychedelic drug ayahuasca by preventing the breakdown of dimethyltryptamine in the gut by reversibly inhibiting monoamine oxidase, thus making it psychoactive upon oral administration. Some β-carbolines, notably tryptoline and pinoline, may be formed naturally in the human body. The latter is possibly implicated along with melatonin in the role of the pineal gland in regulating the sleep-wake cycle. β-carboline is a benzodiazepine receptor inverse agonist and can therefore have convulsive, anxiogenic and memory enhancing effects. 9-methyl-β-carbolines appear to induce DNA damage when exposed to ultra-violet light.

Structure

β-Carboline belongs to the group of indole alkaloids and consist of pyridine ring that is fused to an indole skeleton. The structure of β-carboline is similar to that of tryptamine, with the ethylamine chain re-connected to the indole ring via an extra carbon atom, to produce a three-ringed structure. The biosynthesis of β-carbolines is believed to follow this route from analogous tryptamines. Different levels of saturation are possible in the third ring, which is indicated here in the structural formula by colouring the optionally double bonds red and blue:

Examples of β-carbolines

Some of the more important β-carbolines are tabulated by structure below.

Short Name	Red Bond	Blue Bond	R1	R6	R7	Structure
β-Carboline	×	×	H	H	H
Tryptoline			H	H	H
Pinoline			H	OCH3	H
Harmane	×		CH3	H	H
Harmine	×	×	CH3	H	OCH3
Harmaline	×		CH3	H	OCH3
Tetrahydroharmine			CH3	H	OCH3

Occurrence in nature

Eight plant families are known to express 64 different kinds of β-carboline alkaloids. By dry weight, the seeds of Peganum harmala (Syrian Rue) contain between 0.16% and 5.9% β-carboline alkaloids.

As a result of the presence of β-carbolines in the cuticle of scorpions, their skin is known to fluoresce when exposed to certain wavelengths of ultraviolet light such as that produced by a blacklight.

A group of β-carboline derivatives, termed eudistomins were extracted from ascidians (marine tunicates of the family Ascidiacea), like Ritterella sigillinoides, Lissoclinum fragile or Pseudodistoma aureum. Nostocarboline was isolated from freshwater cyanobacterium.

See also

• Harmala alkaloid
• Tryptamine

External links

• Beta-Carbolines at the US National Library of Medicine Medical Subject Headings (MeSH)
• TiHKAL #44
• TiHKAL in general
• Beta-carbolines in Coffee