The Sunlight Experiment

Compound Monograph

Harmine

Harmine is a beta-carboline alkaloid and reversible MAO-A inhibitor central to the activity of ayahuasca.

Work in progress

Classification

Harmine is a beta-carboline alkaloid, part of the alkaloids class. Nitrogen-containing, often bitter and physiologically potent compounds — the group behind many of the strongest plant medicines and poisons.

Alkaloids Indole Alkaloids

Where Does It Come From? (5)

Harmine is a naturally occurring beta-carboline alkaloid, found in Banisteriopsis caapi, Syrian rue, Passionflower and 2 other sources. It is flagged as moderately toxic.

Banisteriopsis caapiCommon reed Passionflower Passiflora incarnata Syrian rue Tribulus Tribulus terrestris

Research & Evidence

Harmine is a beta-carboline (harmala) alkaloid and one of the principal alkaloids of the ayahuasca vine Banisteriopsis caapi and of Syrian rue. Its key pharmacological action is reversible inhibition of monoamine oxidase A (MAO-A); in traditional ayahuasca preparations this is what enables orally consumed DMT to become active. Harmine has a long history under names such as telepathine and banisterine, and it has attracted modern research interest both for its role in ayahuasca and as a chemical probe in studies of enzymes such as DYRK1A.

Monoamine oxidase (MAO) inhibition

Among plant-derived MAO inhibitors, harmine is one of the most potent ever measured. It’s a reversible, competitive inhibitor selective for MAO-A, with a reported binding constant (Ki) near 5 nM — nanomolar potency, on the order of a thousand times stronger than typical flavonoid inhibitors — while barely touching MAO-B 1Reference 1Kim et al. · 1997Inhibition of monoamine oxidase A by beta-carboline derivativesView study →. That MAO-A selectivity is exactly what lets harmine (and the Syrian rue and ayahuasca vine that carry it) shield orally ingested DMT from first-pass breakdown. See the natural MAO inhibitors guide for how it compares with other plants.

Toxicity & Safety

As an MAO-A inhibitor, harmine carries the interaction risks typical of that class: combining it with serotonergic drugs or tyramine-rich foods can produce dangerous reactions, including serotonin toxicity. It commonly causes nausea and vomiting and should be treated with caution by anyone on other medications.

References

  1. Kim, H., Sablin, S. O., & Ramsay, R. R. (1997). Inhibition of monoamine oxidase A by beta-carboline derivatives. Archives of Biochemistry and Biophysics, 337(1), 137-142. https://pubmed.ncbi.nlm.nih.gov/8990278/