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β-Carboline
IUPAC name 9H-β-carboline
Other names 9H-pyrido[3,4-b]indole
Identifiers
CAS number	244-63-3 Y
PubChem	64961
ChemSpider	58486 Y
MeSH	norharman
ChEBI	CHEBI:109895 Y
ChEMBL	CHEMBL275224 Y
Jmol-3D images	Image 1
SMILES c2cncc3nc1ccccc1c23
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
Properties
Molecular formula	C11H8N2
Molar mass	168.20 g/mol
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
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 monoamine oxidase inhibitors (MAOI). As components of the liana Banisteriopsis caapi, the β-carbolines harmine, harmaline, and tetrahydroharmine play a pivotal role in the pharmacology of the indigenous hallucinogenic drug ayahuasca by preventing the breakdown of dimethyltryptamine in the gut by inhibiting monoamine oxidase, thus making it psychoactive upon oral administration. Some β-carbolines, notably tryptoline and pinoline, are formed naturally in the human body. The latter is implicated along with melatonin in the role of the pineal gland in regulating the sleep-wake cycle.^{[citation needed]} The β-carboline can link to cerebral benzodiazepine receptors and induce inverse agonist effect.

  Structure

β-Carboline belongs to the group of indole alkaloids and consist of pyridine ring that is fused to an indole skeleton.^[1] 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.^[2] 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 H	OCH3

  Occurrence in nature

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"There are presently 64 known β-carboline alkaloids dispersed throughout at least eight plant families." The seeds of Peganum harmala (Syrian Rue) are a good source of beta-carbolines. Estimates of the quantity of harmaline in P. harmala seeds range from 0.16% ^[3] to 5.9% ^[4]of the dried weight. (As for most plants, yields vary with factors such as sub-species, growing conditions and season of collection.)

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.^[5]

Several β-carbolines have actions opposite to those of benzodiazepines: convulsive, anxiogenic and memory enhancing.^[6]

  See also

• Harmala alkaloid
• Tryptamine

  References

  External links

• Beta-Carbolines at the US National Library of Medicine Medical Subject Headings (MeSH)
• TiHKAL #44
• TiHKAL in general
• Beta-carbolines in Coffee
• Farzin D, Mansouri N (July 2006). "Antidepressant-like effect of harmane and other beta-carbolines in the mouse forced swim test". Eur Neuropsychopharmacol 16 (5): 324–8. DOI:10.1016/j.euroneuro.2005.08.005. PMID 16183262.