RESEARCH MONOGRAPH · KDC-MN-337

Harmaline

May 9, 2026 Kodiac biolabs Research Revised May 30, 2026 2 min read

Our opinion on this compound

67/100

Reversible MAO-A inhibitor with real beta-carboline biology and one of the cleaner ayahuasca-component pharmacology profiles

Harmaline is one of the principal beta-carbolines in Banisteriopsis caapi and the molecule that does most of the heavy lifting in the ayahuasca preparation's MAO inhibition. Mechanism is well-mapped: reversible MAO-A selective inhibitor (RIMA) with low-nM affinity, much weaker MAO-B activity, plus additional pharmacology at 5-HT2A and at imidazoline I2 receptors that may or may not be biologically meaningful at typical exposures.

The MAO-A inhibition is what gives oral DMT its activity in ayahuasca: without RIMA accompanying it the DMT gets destroyed by intestinal and hepatic MAO-A before reaching the CNS. Harmaline (and harmine, see separate entry) provide the peripheral MAO-A inhibition that lets the DMT survive first pass. This is well-characterized pharmacologically and is one of the cleaner examples of intentional natural-product polypharmacology.

What people miss: harmaline has its own pharmacological effects independent of the MAO inhibition. Tremorgenic activity at higher doses (the harmaline-induced tremor model in rats is a classical pharmacology preparation, Sinton and colleagues), the I2 imidazoline binding may contribute to some of the dysphoric profile, and the 5-HT2A activity (lower affinity than the classical psychedelics but present) might contribute to the visual/perceptual effects independent of the DMT amplification. The dose-response curve for harmaline alone is not pleasant in most reported experiences.

For research it's a useful selective MAO-A reversible inhibitor with the advantage of being a natural product with extensive characterization. Compared to clinical RIMAs (moclobemide, brofaromine), harmaline has more polypharmacology, which makes it less clean as a selective tool but more interesting as a biology probe.

Sourcing: harmaline hydrochloride is widely available from research suppliers, fairly cheap, HPLC and NMR verification is straightforward. Stability is good as the solid, light-sensitive in solution. Many vendors source from Banisteriopsis caapi extracts and the natural-source material is honestly fine if the purification is documented; synthetic material is also widely available and identical pharmacologically.

What we like: well-characterized MAO-A pharmacology, useful for studying RIMA biology and beta-carboline structure-activity, real natural product with cultural and pharmacological interest.

What we dont like: the tremorgenic activity makes in vivo work at higher doses messy, the I2 imidazoline pharmacology is poorly understood, and the consumer-market 'ayahuasca alternative' framing oversells what the molecule does alone.

Solid research compound with real natural-product pedigree.

Evidence: 60
Mechanism: 75
Reliability: 70
Safety: 60
Sourcing: 78
Value: 75
Signal: 60
Staying power: 60

Plain-language summary Intrigue 60 / 100

Harmaline is one of the three main beta-carboline alkaloids in the ayahuasca vine (Banisteriopsis caapi) and Syrian rue (Peganum harmala). Its critical pharmacological role is reversible MAO-A inhibition, which is what allows oral DMT to reach the brain in ayahuasca brews (without an MAO-A inhibitor, gut MAO destroys oral DMT before it can act centrally). Harmaline by itself produces vivid closed-eye visual imagery at high doses but is not a classical psychedelic. The reversible MAO inhibition is safer than the irreversible MAO inhibitors used as antidepressants but still creates real food and drug interaction risks. Not stocked by Kodiac. This monograph is provided for research and educational reference.

Intrigue 0–100 blends mechanism novelty, evidence strength, and translational potential. Kodiac editorial, not peer-reviewed.

Beta-carboline reversible MAO-A inhibitor

A beta-carboline alkaloid from Peganum harmala and Banisteriopsis caapi; a reversible MAO-A inhibitor and component of ayahuasca.

Abstract

Harmaline (4,9-dihydro-7-methoxy-1-methyl-3H-pyrido[3,4-b]indole; CAS 304-21-2; molecular formula C13H14N2O; molecular weight 214.27) is a beta-carboline alkaloid isolated from Peganum harmala (Syrian rue) and Banisteriopsis caapi (ayahuasca vine). The compound is a reversible MAO-A inhibitor (Ki approximately 5 microM at human MAO-A) with greater than 100-fold selectivity over MAO-B; this reversible MAO-A inhibition is central to the pharmacology of ayahuasca, where harmaline (and harmine) prevent intestinal breakdown of the DMT in the brew, allowing oral activity. Harmaline itself has serotonergic and tremorgenic effects in animals and mild psychoactive effects in humans. Plasma half-life is approximately 2 to 3 hours. Used as a reference reversible MAO-A inhibitor and as a research probe for beta-carboline pharmacology.

Mechanism of action

Reversible MAO-A inhibitor (>100-fold selective over MAO-B). Component of ayahuasca; potentiates oral DMT activity.

Reported research dose ranges

Research and ayahuasca-context use 100 to 300 mg in the published literature.

References

McKenna DJ, et al. Monoamine oxidase inhibitors in South American hallucinogenic plants. Eur J Pharmacol 1984.
Riba J, et al. Pharmacology of ayahuasca administered in two repeated doses. Psychopharmacology 2003.
Iurlo M, et al. Pharmacokinetics and pharmacodynamics of harmine and harmaline. CNS Drug Rev 2001.

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KDC-MN-337

The full reference document is provided strictly for research use only. It reports research dose ranges from the published literature, not instructions for use in humans or animals.

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FOR RESEARCH USE ONLY. Not for medical, diagnostic, or therapeutic purposes. Not for human consumption. All information is provided for research and educational purposes only.

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Harmaline

Abstract

Mechanism of action

Reported research dose ranges

References

Read the full monograph

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Abstract

Mechanism of action

Reported research dose ranges

References

Read the full monograph

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