Β-Carboline

Last updated

Contents

β-Carboline
Beta-Carboline.svg
B-Carboline.png
Names
Preferred IUPAC name
9H-Pyrido[3,4-b]indole
Other names
  • Norharmane
  • Norharman
  • Carbazoline
  • 2-Azacarbazole
  • 2,9-Diazafluorene
Identifiers
3D model (JSmol)
128414
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.005.418 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 205-959-0
KEGG
MeSH norharman
PubChem CID
UNII
  • InChI=1S/C11H8N2/c1-2-4-10-8(3-1)9-5-6-12-7-11(9)13-10/h1-7,13H Yes check.svgY
    Key: AIFRHYZBTHREPW-UHFFFAOYSA-N Yes check.svgY
  • 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
  • c1ccc3c(c1)[nH]c2cnccc23
Properties
C11H8N2
Molar mass 168.20 g/mol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Yes check.svgY  verify  (what is  Yes check.svgYX mark.svgN ?)

β-Carboline (9H-pyrido[3,4-b]indole) represents the basic chemical structure for more than one hundred alkaloids and synthetic compounds. The effects of these substances depend on their respective substituent. Natural β-carbolines primarily influence brain functions but can also exhibit antioxidant [1] effects. Synthetically designed β-carboline derivatives have recently been shown to have neuroprotective, [2] cognitive enhancing and anti-cancer properties. [3]

Pharmacology

The pharmacological effects of specific β-carbolines are dependent on their substituents. For example, the natural β-carboline harmine has substituents on position 7 and 1. Thereby, it acts as a selective inhibitor of the DYRK1A protein kinase, a protein necessary for neurodevelopment. [4] [5] It also exhibits various antidepressant-like effects in rats by interacting with serotonin receptor 2A. [6] [7] Furthermore, it increases levels of the brain-derived neurotrophic factor (BDNF) in rat hippocampus. [7] [8] A decreased BDNF level has been associated with major depression in humans. The antidepressant effect of harmine might also be due to its function as a MAO-A inhibitor by reducing the breakdown of serotonin and noradrenaline. [8] [9]

A synthetic derivative, 9-methyl-β-carboline, has shown neuroprotective effects including increased expression of neurotrophic factors and enhanced respiratory chain activity. [10] [11] This derivative has also been shown to enhance cognitive function, [12] increase dopaminergic neuron count and facilitate synaptic and dendritic proliferation. [13] [14] It also exhibited therapeutic effects in animal models for Parkinson's disease and other neurodegenerative processes. [11]

However, β-carbolines with substituents in position 3 reduce the effect of benzodiazepine on GABA-A receptors and can therefore have convulsive, anxiogenic and memory enhancing effects. [15] Moreover, 3-hydroxymethyl-beta-carboline blocks the sleep-promoting effect of flurazepam in rodents and – by itself – can decrease sleep in a dose-dependent manner. [16] Another derivative, methyl-β-carboline-3-carboxylate, stimulates learning and memory at low doses but can promote anxiety and convulsions at high doses. [15] With modification in position 9 similar positive effects have been observed for learning and memory without promotion of anxiety or convulsion. [12]

β-carboline derivatives also enhance the production of the antibiotic reveromycin A in soil-dwelling Streptomyces species. [17] [18] Specifically, expression of biosynthetic genes is facilitated by binding of the β-carboline to a large ATP-binding regulator of the LuxR family.

Also Lactobacillus spp. secretes a β-carboline (1-acetyl-β-carboline) preventing the pathogenic fungus Candida albicans to change to a more virulent growth form (yeast-to-filament transition). Thereby, β-carboline reverses imbalances in the microbiome composition causing pathologies ranging from vaginal candidiasis to fungal sepsis. [19]

Since β-carbolines also interact with various cancer-related molecules such as DNA, enzymes (GPX4, kinases, etc.) and proteins (ABCG2/BRCP1, etc.), they are also discussed as potential anticancer agents. [3]

Explorative human studies for the medical use of β-carbolines

The extract of the liana Banisteriopsis caapi has been used by the tribes of the Amazon as an entheogen and was described as a hallucinogen in the middle of the 19th century. [20] In early 20th century, European pharmacists identified harmine as the active substance. [21] This discovery stimulated the interest to further investigate its potential as a medicine. For example, Louis Lewin, a prominent pharmacologist, demonstrated a dramatic benefit in neurological impairments after injections of B. caapi in patients with postencephalitic Parkinsonism. [20] By 1930, it was generally agreed that hypokinesia, drooling, mood, and sometimes rigidity improved by treatment with harmine. Altogether, 25 studies had been published in the 1920s and 1930s about patients with Parkinson's disease and postencephalitic Parkinsonism. The pharmacological effects of harmine have been attributed mainly to its central monoamine oxidase (MAO) inhibitory properties. In-vivo and rodent studies have shown that extracts of Banisteriopsis caapi and also Peganum harmala lead to striatal dopamine release. [22] [23] [24] Furthermore, harmine supports the survival of dopaminergic neurons in MPTP-treated mice. [25] Since harmine also antagonizes N-methyl-d-aspartate (NMDA) receptors, [26] some researchers speculatively attributed the rapid improvement in patients with Parkinson's disease to these antiglutamatergic effects. [20] However, the advent of synthetic anticholinergic drugs at that time led to the total abandonment of harmine. [20]

Structure

β-Carbolines belong to the group of indole alkaloids and consist of a pyridine ring that is fused to an indole skeleton. [27] 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. [28] Different levels of saturation are possible in the third ring which is indicated here in the structural formula by coloring the optionally double bonds red and blue:

Substituted beta-carbolines (structural formula) Betacarbolines.png
Substituted beta-carbolines (structural formula)

Examples of β-carbolines

Some of the more important β-carbolines are tabulated by structure below. Their structures may contain the aforementioned bonds marked by red or blue.

Short nameR1R6R7R9Structure
β-CarbolineHHHH Beta-Carboline.svg
Tryptoline HHHH Tryptoline.svg
Pinoline H OCH3 HH Pinoline.svg
Harmane CH3 HHH Harmane structure.svg
Harmine CH3 H OCH3 H Harmine structure.svg
Harmaline CH3 H OCH3 H Harmaline structure.svg
Harmalol CH3 H OH H Harmalol structure.svg
Tetrahydroharmine CH3 H OCH3 H Tetrahydroharmine structure.svg
9-Methyl-β-carboline HHH CH3 9-Me-BC bkchem autocropped.svg
3-Carboxy-TetrahydrononharmanH / CH3 / COOHHHH 3-Carboxy-Tetrahydronorharman3.svg

Natural occurrence

A Paruroctonus scorpion fluorescing under a blacklight Arachnida, Scorpiones, Paruroctonus scorpion under UV (4818403697).jpg
A Paruroctonus scorpion fluorescing under a blacklight

β-Carboline alkaloids are widespread in prokaryotes, plants and animals. Some β-carbolines, notably tetrahydro-β-carbolines, may be formed naturally in plants and the human body with tryptophan, serotonin and tryptamine as precursors.

See also

Related Research Articles

<span class="mw-page-title-main">Ayahuasca</span> South American psychoactive brew

Ayahuasca is a South American psychoactive beverage, traditionally used by Indigenous cultures and folk healers in the Amazon and Orinoco basins for spiritual ceremonies, divination, and healing a variety of psychosomatic complaints.

<i>N</i>,<i>N</i>-Dimethyltryptamine Chemical compound

N,N-Dimethyltryptamine is a substituted tryptamine that occurs in many plants and animals, including humans, and which is both a derivative and a structural analog of tryptamine. DMT is used as a psychedelic drug and prepared by various cultures for ritual purposes as an entheogen.

<i>Banisteriopsis caapi</i> Species of plant

Banisteriopsis caapi, also known as, caapi, soul vine, yagé (yage), or ayahuasca, the latter of which also refers to the psychedelic decoction made with the vine and a plant source of dimethyltryptamine, is a South American liana of the family Malpighiaceae. It is commonly used as an ingredient of ayahuasca, a decoction with a long history of its entheogenic use and holds status as a "plant teacher" among the Indigenous peoples of the Amazon rainforest.

<span class="mw-page-title-main">Tryptamine</span> Metabolite of the amino acid tryptophan

Tryptamine is an indolamine metabolite of the essential amino acid tryptophan. The chemical structure is defined by an indole—a fused benzene and pyrrole ring, and a 2-aminoethyl group at the second carbon. The structure of tryptamine is a shared feature of certain aminergic neuromodulators including melatonin, serotonin, bufotenin and psychedelic derivatives such as dimethyltryptamine (DMT), psilocybin, psilocin and others.

<span class="mw-page-title-main">Harmala alkaloid</span> Group of chemical compounds

Harmala alkaloids are several alkaloids that act as monoamine oxidase inhibitors (MAOIs). These alkaloids are found in the seeds of Peganum harmala, as well as Banisteriopsis caapi (ayahuasca), leaves of tobacco and coffee beans. The alkaloids include harmine, harmaline, harmalol, and their derivatives, which have similar chemical structures, hence the name "harmala alkaloids". These alkaloids are of interest for their use in Amazonian shamanism, where they are derived from other plants. Harmine, once known as telepathine and banisterine, is a naturally occurring beta-carboline alkaloid that is structurally related to harmaline, and also found in the vine Banisteriopsis caapi. Tetrahydroharmine is also found in B. caapi and P. harmala. Dr. Alexander Shulgin has suggested that harmine may be a breakdown product of harmaline. Harmine and harmaline are reversible inhibitors of monoamine oxidase A (RIMAs). They can stimulate the central nervous system by inhibiting the metabolism of monoamine compounds such as serotonin and norepinephrine.

<i>Peganum harmala</i> Species of plant

Peganum harmala, commonly called wild rue, Syrian rue, African rue, esfand or espand, or harmel, is a perennial, herbaceous plant, with a woody underground rootstock, of the family Nitrariaceae, usually growing in saline soils in temperate desert and Mediterranean regions. Its common English-language name came about because of a resemblance to rue. Because eating it would sicken or kill livestock, it is considered a noxious weed in a number of countries. It has become an invasive species in some regions of the western United States. The plant is popular in Middle Eastern and north African folk medicine. The alkaloids contained in the plant, including the seeds, are monoamine oxidase inhibitors.

Harmine is a beta-carboline and a harmala alkaloid. It occurs in a number of different plants, most notably the Syrian rue and Banisteriopsis caapi. Harmine reversibly inhibits monoamine oxidase A (MAO-A), an enzyme which breaks down monoamines, making it a Reversible inhibitor of monoamine oxidase A (RIMA). Harmine does not inhibit MAO-B. Harmine is also known as banisterin, banisterine, telopathin, telepathine, leucoharmine and yagin, yageine.

<span class="mw-page-title-main">Harmaline</span> Chemical compound

Harmaline is a fluorescent indole alkaloid from the group of harmala alkaloids and beta-carbolines. It is the partly hydrogenated form of harmine.

<span class="mw-page-title-main">Tetrahydroharmine</span> Chemical compound

Tetrahydroharmine (THH) is a fluorescent indole alkaloid that occurs in the tropical liana species Banisteriopsis caapi.

Pharmahuasca is a pharmaceutical version of the entheogenic brew ayahuasca. Traditional ayahuasca is made by brewing the MAOI-containing Banisteriopsis caapi vine with a DMT-containing plant, such as Psychotria viridis. Pharmahuasca refers to a similar combination that uses a pharmaceutical MAOI instead of a plant.

<span class="mw-page-title-main">Dopaminergic</span> Substance related to dopamine functions

Dopaminergic means "related to dopamine", a common neurotransmitter. Dopaminergic substances or actions increase dopamine-related activity in the brain.

<span class="mw-page-title-main">Indole alkaloid</span> Class of alkaloids

Indole alkaloids are a class of alkaloids containing a structural moiety of indole; many indole alkaloids also include isoprene groups and are thus called terpene indole or secologanin tryptamine alkaloids. Containing more than 4100 known different compounds, it is one of the largest classes of alkaloids. Many of them possess significant physiological activity and some of them are used in medicine. The amino acid tryptophan is the biochemical precursor of indole alkaloids.

<span class="mw-page-title-main">Tryptoline</span> Chemical compound

Tryptoline, also known as tetrahydro-β-carboline and tetrahydronorharmane, is a natural organic derivative of beta-carboline. It is an alkaloid chemically related to tryptamines. Derivatives of tryptoline have a variety of pharmacological properties and are known collectively as tryptolines.

<span class="mw-page-title-main">Tetrahydroharman</span> Chemical compound

Tetrahydroharman(e), also known as 1-methyl-1,2,3,4-tetrahydro-β-carboline, is a general name for one of two isomers:

  1. (1S)-1-methyl-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indole
  2. Calligonine ((1R)-1-methyl-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indole)
<span class="mw-page-title-main">Harmane</span> Chemical compound

Harmane (harman) is a heterocyclic amine found in a variety of foods including coffee, sauces, and cooked meat. It is also present in tobacco smoke.

<span class="mw-page-title-main">Eudistomin</span>

Eudistomins are β-carboline derivatives, isolated from ascidians, like Ritterella sigillinoides, Lissoclinum fragile, or Pseudodistoma aureum.

<span class="mw-page-title-main">Harmol</span> Chemical compound

Harmol is a chemical compound classified as a β-carboline. It is readily formed in vivo in humans by O-demethylation of harmine.

<span class="mw-page-title-main">9-Methyl-β-carboline</span> Chemical compound

9-Methyl-β-carboline (9-Me-BC) is a heterocyclic amine of the β-carboline family, and a research chemical.

<span class="mw-page-title-main">Ibogaline</span> Alkaloid found in Tabernanthe iboga

Ibogaline is an alkaloid found in Tabernanthe iboga along with the related chemical compounds ibogaine, ibogamine, and other minor alkaloids. It is a relatively smaller component of Tabernanthe iboga root bark total alkaloids (TA) content. It is also present in Tabernaemontana species such as Tabernaemontana australis which shares similar ibogan-biosynthetic pathways. The percentage of ibogaline in T. iboga root bark is up to 15% TA with ibogaine constituting 80% of the alkaloids and ibogamine up to 5%.

References

  1. Francik R, Kazek G, Cegła M, Stepniewski M (March 2011). "Antioxidant activity of beta-carboline derivatives". Acta Poloniae Pharmaceutica. 68 (2): 185–189. PMID   21485291.
  2. Gulyaeva N, Aniol V (June 2012). "Good guys from a shady family". Journal of Neurochemistry. 121 (6): 841–842. doi: 10.1111/j.1471-4159.2012.07708.x . PMID   22372749. S2CID   205624339.
  3. 1 2 Aaghaz S, Sharma K, Jain R, Kamal A (April 2021). "β-Carbolines as potential anticancer agents". European Journal of Medicinal Chemistry. 216: 113321. doi:10.1016/j.ejmech.2021.113321. PMID   33684825. S2CID   232159513.
  4. Mennenga SE, Gerson JE, Dunckley T, Bimonte-Nelson HA (January 2015). "Harmine treatment enhances short-term memory in old rats: Dissociation of cognition and the ability to perform the procedural requirements of maze testing". Physiology & Behavior. 138: 260–265. doi:10.1016/j.physbeh.2014.09.001. PMC   4406242 . PMID   25250831.
  5. Becker W, Sippl W (January 2011). "Activation, regulation, and inhibition of DYRK1A". The FEBS Journal. 278 (2): 246–256. doi: 10.1111/j.1742-4658.2010.07956.x . PMID   21126318. S2CID   27837814.
  6. Glennon RA, Dukat M, Grella B, Hong S, Costantino L, Teitler M, et al. (August 2000). "Binding of beta-carbolines and related agents at serotonin (5-HT(2) and 5-HT(1A)), dopamine (D(2)) and benzodiazepine receptors". Drug and Alcohol Dependence. 60 (2): 121–132. doi:10.1016/s0376-8716(99)00148-9. PMID   10940539.
  7. 1 2 Fortunato JJ, Réus GZ, Kirsch TR, Stringari RB, Stertz L, Kapczinski F, et al. (November 2009). "Acute harmine administration induces antidepressive-like effects and increases BDNF levels in the rat hippocampus". Progress in Neuro-Psychopharmacology & Biological Psychiatry. Bed nucleus of the stria terminalis: anatomy, physiology, functions. 33 (8): 1425–1430. doi: 10.1016/j.pnpbp.2009.07.021 . PMID   19632287. S2CID   207408868.
  8. 1 2 Fortunato JJ, Réus GZ, Kirsch TR, Stringari RB, Fries GR, Kapczinski F, et al. (October 2010). "Chronic administration of harmine elicits antidepressant-like effects and increases BDNF levels in rat hippocampus". Journal of Neural Transmission. 117 (10): 1131–1137. doi:10.1007/s00702-010-0451-2. PMID   20686906. S2CID   21595062.
  9. López-Muñoz F, Alamo C (2009-05-01). "Monoaminergic neurotransmission: the history of the discovery of antidepressants from 1950s until today". Current Pharmaceutical Design. 15 (14): 1563–1586. doi:10.2174/138161209788168001. PMID   19442174.
  10. Antkiewicz-Michaluk L, Rommelspacher H, eds. (2012). Isoquinolines And Beta-Carbolines As Neurotoxins And Neuroprotectants. doi:10.1007/978-1-4614-1542-8. ISBN   978-1-4614-1541-1. S2CID   28551023.
  11. 1 2 Wernicke C, Hellmann J, Zieba B, Kuter K, Ossowska K, Frenzel M, et al. (January 2010). "9-Methyl-beta-carboline has restorative effects in an animal model of Parkinson's disease". Pharmacological Reports. 62 (1): 35–53. doi:10.1016/s1734-1140(10)70241-3. PMID   20360614. S2CID   16729205.
  12. 1 2 Gruss M, Appenroth D, Flubacher A, Enzensperger C, Bock J, Fleck C, et al. (June 2012). "9-Methyl-β-carboline-induced cognitive enhancement is associated with elevated hippocampal dopamine levels and dendritic and synaptic proliferation". Journal of Neurochemistry. 121 (6): 924–931. doi: 10.1111/j.1471-4159.2012.07713.x . PMID   22380576. S2CID   8832937.
  13. Hamann J, Wernicke C, Lehmann J, Reichmann H, Rommelspacher H, Gille G (March 2008). "9-Methyl-beta-carboline up-regulates the appearance of differentiated dopaminergic neurones in primary mesencephalic culture". Neurochemistry International. 52 (4–5): 688–700. doi:10.1016/j.neuint.2007.08.018. PMID   17913302. S2CID   24226033.
  14. Polanski W, Reichmann H, Gille G (June 2011). "Stimulation, protection and regeneration of dopaminergic neurons by 9-methyl-β-carboline: a new anti-Parkinson drug?". Expert Review of Neurotherapeutics. 11 (6): 845–860. doi:10.1586/ern.11.1. PMID   21651332. S2CID   24899640.
  15. 1 2 Venault P, Chapouthier G (February 2007). "From the behavioral pharmacology of beta-carbolines to seizures, anxiety, and memory". TheScientificWorldJournal. 7: 204–223. doi: 10.1100/tsw.2007.48 . PMC   5901106 . PMID   17334612.
  16. Mendelson WB, Cain M, Cook JM, Paul SM, Skolnick P (January 1983). "A benzodiazepine receptor antagonist decreases sleep and reverses the hypnotic actions of flurazepam". Science. 219 (4583): 414–416. Bibcode:1983Sci...219..414M. doi:10.1126/science.6294835. PMID   6294835. S2CID   43038332.
  17. Panthee S, Takahashi S, Hayashi T, Shimizu T, Osada H (April 2019). "β-carboline biomediators induce reveromycin production in Streptomyces sp. SN-593". Scientific Reports. 9 (1): 5802. Bibcode:2019NatSR...9.5802P. doi: 10.1038/s41598-019-42268-w . PMC   6456619 . PMID   30967594.
  18. Panthee S, Kito N, Hayashi T, Shimizu T, Ishikawa J, Hamamoto H, et al. (June 2020). "β-carboline chemical signals induce reveromycin production through a LuxR family regulator in Streptomyces sp. SN-593". Scientific Reports. 10 (1): 10230. Bibcode:2020NatSR..1010230P. doi: 10.1038/s41598-020-66974-y . PMC   7311520 . PMID   32576869.
  19. MacAlpine J, Daniel-Ivad M, Liu Z, Yano J, Revie NM, Todd RT, et al. (October 2021). "A small molecule produced by Lactobacillus species blocks Candida albicans filamentation by inhibiting a DYRK1-family kinase". Nature Communications. 12 (1): 6151. Bibcode:2021NatCo..12.6151M. doi:10.1038/s41467-021-26390-w. PMC   8536679 . PMID   34686660.
  20. 1 2 3 4 Djamshidian A, Bernschneider-Reif S, Poewe W, Lees AJ (2016). "Banisteriopsis caapi, a Forgotten Potential Therapy for Parkinson's Disease?". Movement Disorders Clinical Practice. 3 (1): 19–26. doi:10.1002/mdc3.12242. PMC   6353393 . PMID   30713897.
  21. Foley P (2003). "Beans, roots and leaves: a brief history of the pharmacological therapy of parkinsonism". Wurzburger Medizinhistorische Mitteilungen. 22: 215–234. PMID   15641199.
  22. Schwarz MJ, Houghton PJ, Rose S, Jenner P, Lees AD (June 2003). "Activities of extract and constituents of Banisteriopsis caapi relevant to parkinsonism". Pharmacology, Biochemistry, and Behavior. 75 (3): 627–633. doi:10.1016/s0091-3057(03)00129-1. PMID   12895680. S2CID   28243440.
  23. Brierley DI, Davidson C (January 2013). "Harmine augments electrically evoked dopamine efflux in the nucleus accumbens shell". Journal of Psychopharmacology. 27 (1): 98–108. doi:10.1177/0269881112463125. PMID   23076833. S2CID   40115950.
  24. Samoylenko V, Rahman MM, Tekwani BL, Tripathi LM, Wang YH, Khan SI, et al. (February 2010). "Banisteriopsis caapi, a unique combination of MAO inhibitory and antioxidative constituents for the activities relevant to neurodegenerative disorders and Parkinson's disease". Journal of Ethnopharmacology. 127 (2): 357–367. doi:10.1016/j.jep.2009.10.030. PMC   2828149 . PMID   19879939.
  25. Barallobre MJ, Perier C, Bové J, Laguna A, Delabar JM, Vila M, Arbonés ML (June 2014). "DYRK1A promotes dopaminergic neuron survival in the developing brain and in a mouse model of Parkinson's disease". Cell Death & Disease. 5 (6): e1289. doi:10.1038/cddis.2014.253. PMC   4611726 . PMID   24922073.
  26. Du W, Aloyo VJ, Harvey JA (October 1997). "Harmaline competitively inhibits [3H]MK-801 binding to the NMDA receptor in rabbit brain". Brain Research. 770 (1–2): 26–29. doi:10.1016/s0006-8993(97)00606-9. PMID   9372198. S2CID   10309111.
  27. The Encyclopedia of Psychoactive Plants: Ethnopharmacology and its Applications. Ratsch, Christian. Park Street Press c. 2005
  28. Baiget J, Llona-Minguez S, Lang S, Mackay SP, Suckling CJ, Sutcliffe OB (2011). "Manganese dioxide mediated one-pot synthesis of methyl 9H-pyrido[3,4-b]indole-1-carboxylate: Concise synthesis of alangiobussinine". Beilstein Journal of Organic Chemistry. 7: 1407–1411. doi:10.3762/bjoc.7.164. PMC   3201054 . PMID   22043251.
  29. Hemmateenejad B, Abbaspour A, Maghami H, Miri R, Panjehshahin MR (August 2006). "Partial least squares-based multivariate spectral calibration method for simultaneous determination of beta-carboline derivatives in Peganum harmala seed extracts". Analytica Chimica Acta. 575 (2): 290–299. Bibcode:2006AcAC..575..290H. doi:10.1016/j.aca.2006.05.093. PMID   17723604.
  30. Herraiz T, González D, Ancín-Azpilicueta C, Arán VJ, Guillén H (March 2010). "beta-Carboline alkaloids in Peganum harmala and inhibition of human monoamine oxidase (MAO)". Food and Chemical Toxicology. 48 (3): 839–845. doi:10.1016/j.fct.2009.12.019. hdl:10261/77694. PMID   20036304.
  31. Lake RJ, Blunt JW, Munro MH (1989). "Eudistomins from the New Zealand ascidian Ritterella sigillinoides". Aust. J. Chem. 42 (7): 1201–1206. doi:10.1071/CH9891201.
  32. Badre A, Boulanger A, Abou-Mansour E, Banaigs B, Combaut G, Francisco C (April 1994). "Eudistomin U and isoeudistomin U, new alkaloids from the Caribbean ascidian Lissoclinum fragile". Journal of Natural Products. 57 (4): 528–533. doi:10.1021/np50106a016. PMID   8021654.
  33. Davis RA, Carroll AR, Quinn RJ (July 1998). "Eudistomin V, a new beta-carboline from the Australian ascidian Pseudodistoma aureum". Journal of Natural Products. 61 (7): 959–960. doi:10.1021/np9800452. PMID   9677285.
  34. Becher PG, Beuchat J, Gademann K, Jüttner F (December 2005). "Nostocarboline: isolation and synthesis of a new cholinesterase inhibitor from Nostoc 78-12A". Journal of Natural Products. 68 (12): 1793–1795. doi:10.1021/np050312l. PMID   16378379.
  35. Herraiz T (2011-11-10), "β-Carbolines as Neurotoxins", Isoquinolines And Beta-Carbolines As Neurotoxins And Neuroprotectants, Boston, MA: Springer US, pp. 77–103, doi:10.1007/978-1-4614-1542-8_5, ISBN   978-1-4614-1541-1 , retrieved 2021-11-16
  36. Herraiz T, González D, Ancín-Azpilicueta C, Arán V, Guillén H (March 2010). "β-Carboline alkaloids in Peganum harmala and inhibition of human monoamine oxidase (MAO)". Food and Chemical Toxicology. 48 (3): 839–845. doi:10.1016/j.fct.2009.12.019. ISSN   0278-6915. PMID   20036304.
  37. Stachel SJ, Stockwell SA, Van Vranken DL (August 1999). "The fluorescence of scorpions and cataractogenesis". Chemistry & Biology. 6 (8): 531–539. doi: 10.1016/S1074-5521(99)80085-4 . PMID   10421760.
  38. Abe N, Nakakita Y, Nakamura T, Enoki N, Uchida H, Takeo S, Munekata M (1993). "Novel cytocidal compounds, oxopropalines from Streptomyces sp. G324 producing lavendamycin. I. Taxonomy of the producing organism, fermentation, isolation and biological activities". J. Antibiot. 46 (11): 1672–1677. doi: 10.7164/antibiotics.46.1672 . PMID   8270488.