Harmaline
Also known asDihydroharmine · Harmidine · Armalin · 3,4-Dihydroharmine · O-Methylharmalol · Harmalol methyl ether · harmalin · Dihydroharmine;
7-methoxy-1-methyl-4,9-dihydro-3H-pyrido[3,4-b]indole
- PubChem CID
- 3564
- ChEMBL
- CHEMBL340807
- Measurements
- 9
- InChIKey
- RERZNCLIYCABFS-UHFFFAOYSA-N
I · Summary
What is known
Published passages, each quoted whole and attributed to the database that published it. Two blocks are written here rather than quoted, and both say so where they stand: the synthesized summary at the top, which may draw only on the passages beneath it, and the history note, which cites the works it came from. Every claim in either carries a marker to its source.
What it is
Harmaline is a harmala alkaloid in which the harman skeleton is methoxy-substituted at C-7 and has been reduced across the 3,4 bond. It has a role as a oneirogen. It derives from a hydride of a harman.
harmaline has been reported in Passiflora phoenicia, Passiflora amethystina, and other organisms with data available.
harmaline has been reported in Peganum harmala with data available.
Recognized use
/EXPL THER/ Oxidative modification of low-density lipoprotein (LDL) particles has been implicated in the process of atherogenesis. Antioxidants that prevent LDL from oxidation may reduce atherosclerosis. We have investigated the protective effect of Peganum harmala-extract (P-extract) and the two major alkaloids (harmine and harmaline) from the seeds of P. harmala against CuSO4-induced LDL oxidation. Through determination of the formation of malondialdehyde (MDA) and conjugated diene as well as the lag phase, the extract (P-extract) and compounds were found to possess an inhibitory effect. Moreover, harmaline and harmine reduced the rate of vitamin E disappearance and exhibited a significant…
Hazardous Substances Data Bank (HSDB)PMID 16805957Berrougui H et al; J Pharm Pharmacol. 2006 Jul;58(7):967-74 (2006)
How it acts
Three psychological active principles from the seeds of Peganum harmala L., harmine, harmaline and harmalol, showed vasorelaxant activities in isolated rat thoracic aorta preparations precontracted by phenylephrine or KCl with rank order of relaxation potency of harmine > harmaline > harmalol. The vasorelaxant effects of harmine and harmaline (but not harmalol) were attenuated by endothelium removal or pretreatment with a nitric oxide (NO) synthase Nomega-nitro-L-arginine methyl ester. In cultured rat aortic endothelial cells, harmine and harmaline (but not harmalol) increased NO release, which was dependent on the presence of external Ca2+. In endothelium-denuded preparations, pretreatment…
Hazardous Substances Data Bank (HSDB)PMID 11325023Shi CC et al; Jpn J Pharmacol 85 (3): 299-305 (2001)
Behavior carries the pharmacological classes and the acute-effect durations, with plasma half-life kept separate from duration of effect.
In the body
Harmaline, a known type A monoamine oxidase (MAO) inhibitor in adult brain of various species was found to elevate whole brain levels of dopamine and serotonin (5-HT) in rat fetuses of mothers injected 2-4 hr before Caesarean delivery. Similar stimulatory effects were observed for the norepinephrine metabolite 3-methoxy-4-hydroxy-phenylglycol (MHPG), however, no significant effect was obtained for norepinephrine. The dopamine metabolite, 3,4-dihydroxyphenylacetic acid (DOPAC) and the 5-HT metabolite 5-hydroxyindole acetic acid (5-HIAA) were decreased with the same treatment. These results imply that harmaline or one of its metabolites may cross the placental barrier to affect the fetal brain…
Absorption, Distribution and Excretion
Hazardous Substances Data Bank (HSDB)PMID 2465555Okonmah AD et al; Pharmacology 37 (3): 203-8 (1988)
The psychotropic beta-carboline alkaloids, showing high affinity for 5-hydroxytryptamine, dopamine, benzodiazepine, and imidazoline receptors and the stimulation of locus coeruleus neurons, are formed endogenously from tryptophan-derived indolealkylamines through the Pictet-Spengler condensation with aldehydes in both plants and mammals. Cytochromes P450 1A1 (18.5), 1A2 (20), and 2D6 (100) catalyzed the O-demethylation of harmaline, and CYP1A1 (98.5), CYP1A2 (35), CYP2C9 (16), CYP2C19 (30), and CYP2D6 (115) catalyzed that of harmine (relative activities). The dehydrogenation/aromatization of harmaline to harmine was not carried out by aromatase (CYP19), CYP1A2, CYP2C9, CYP2D6, CYP3A4, pooled…
Metabolism/Metabolites
Hazardous Substances Data Bank (HSDB)PMID 12649384Yu AM et al; J Pharmacol Exp Ther 305 (1): 315-22 (2003)
Harmaline has known human metabolites that include Harmalol.
Metabolism/Metabolites
NORMAN Suspect List ExchangeS73 | METXBIODB | Metabolite Reaction Database from BioTransformer | DOI:10.5281/zenodo.4056560
History, discovery and cultural use
— Not in this archive. PubChem, ChEMBL and the Human Protein Atlas publish pharmacology, regulation and toxicology, and none of them publishes a heading for when Harmaline was first made, by whom, or how it has been used. That is a gap in the databases this site reads and not a gap in the literature — the history of these compounds is written, at length and under peer review, in the works below. This site does not summarize them; it says where they are. Where a published passage above happens to touch origin or traditional use, it appears inside the entry that carries it.
Histories of this field
Scholarship on psychedelics generally, not on Harmaline specifically. Whether any of these treats this compound is a question for the book, not for this page.
Mescaline: A Global History of the First Psychedelic
Traces mescaline and the peyote and San Pedro cacti from pre-Columbian ritual use through nineteenth-century chemistry to twentieth-century psychiatry and the counterculture.
Jay M. Mescaline: A Global History of the First Psychedelic. Yale University Press, New Haven and London; 2019. ISBN 9780300231076.
Expanding Mindscapes: A Global History of Psychedelicsopen access
Essays on the international and cross-cultural history of psychedelic science, deliberately decentring the standard North American and European account.
Dyck E, Elcock C, editors. Expanding Mindscapes: A Global History of Psychedelics. The MIT Press, Cambridge MA; 2023. ISBN 9780262546935 (paper), 9780262376891 (open access). doi:10.7551/mitpress/14417.001.0001.
Plants of the Gods: Their Sacred, Healing, and Hallucinogenic Powers
Botany, ethnography and chemistry of the principal hallucinogenic plants, by the founder of modern ethnobotany and the chemist who first synthesized LSD.
Schultes RE, Hofmann A, Rätsch C. Plants of the Gods: Their Sacred, Healing, and Hallucinogenic Powers. 2nd ed. Healing Arts Press, Rochester VT; 2001. ISBN 9780892819799.
Psychonauts: Drugs and the Making of the Modern Mind
The tradition of scientific self-experimentation with psychoactive drugs, and its part in the emergence of psychology and of modernism.
Jay M. Psychonauts: Drugs and the Making of the Modern Mind. Yale University Press, New Haven; 2023. ISBN 9780300257946.
Ancient Psychoactive Substances
Archaeological and bioarchaeological evidence for psychoactive plant use across the ancient world.
Fitzpatrick SM, editor. Ancient Psychoactive Substances. University Press of Florida, Gainesville; 2018. ISBN 9780813056708.
A chapter tracing psychedelic and entactogen research from earlier ritual use through the mid-century research period to current clinical trials.
Stroud C, Posey Norris SM, Matney C, editors. History and Current Status of Psychedelics and Entactogens for the Treatment of Psychiatric Disorders. In: Exploring Psychedelics and Entactogens as Treatments for Psychiatric Disorders: Proceedings of a Workshop. National Academies Press, Washington DC; 2022. NBK587225.
Workshop proceedings record what participants said; they are not a consensus statement of the National Academies.
Peer-reviewed review covering the isolation, synthesis, pharmacology and ritual use of peyote and mescaline.
Dinis-Oliveira RJ, Pereira CL, da Silva DD. Pharmacokinetic and Pharmacodynamic Aspects of Peyote and Mescaline: Clinical and Forensic Repercussions. Current Molecular Pharmacology 12(3):184–194; 2019. doi:10.2174/1874467211666181010154139.
Institutional archives
- Heffter Research Institute Funds and coordinates clinical research on psilocybin, and keeps records of the studies it has supported since 1993. Sponsors the research it archives.
- Multidisciplinary Association for Psychedelic Studies (MAPS) Sponsors clinical research, chiefly on MDMA-assisted therapy, and publishes an archive of historical and contemporary documents. A sponsor and an advocacy organization, not a disinterested archive; its clinical programme has a commercial arm.
The rest of this dossier
- Affinity — 9 measurements in this archive, equilibrium constants kept apart from functional readouts.
- Toxicology — 1 published passage, plus any assay in this archive bearing on toxicity.
- Legal — no DEA record is held here — which is not a finding that this compound is uncontrolled.
- Systems — where this compound’s targets are transcribed, by brain region and tissue.
Passages via PubChem descriptive sections, aggregating DrugBank, LiverTox, FDA, DEA, HSDB, EPA. Each is quoted whole and attributed to the database that published it. The only prose written here about Harmaline is the history note, which says so on its face and carries a reference for every claim in it.
II · Identity
Structure and descriptors
Descriptors are computed here with RDKit from the structure PubChem returns — not from the archive's stored copy, so an edited local structure cannot reach this table.
- Formula
- C13H14N2OR
- Molecular weight
- 214.27g/molR
- Exact mass
- 214.1106DaR
- cLogP
- 2.54R
- TPSA
- 37.4ŲR
- H-bond donors
- 1R
- H-bond acceptors
- 2R
- Rotatable bonds
- 1R
- Aromatic rings
- 2R
- Heavy atoms
- 16R
- Fraction sp³
- 0.308R
- Formal charge
- 0R
Computed with RDKit 2025.09.2 from the SMILES returned by PubChem. Audit run 26/09/2026.
III · Behavior
Behavioral summary
Class, mechanism, and the duration of acute effects — each quoted from the record or trial that publishes it. Duration of effects and plasma half-life are shown separately, because they are different quantities and diverge by a factor of three or four.
Classification
Duration of acute subjective effects
—
No controlled human trial reporting a duration for this compound is cited here. The archive does hold onset and duration ranges for it, inherited from an earlier build, but their source column is empty and so they cannot be shown. A duration is not inferred from a chemical relative.
Plasma elimination half-life
How fast the body clears the drug — not how long the effects last. The two diverge sharply: LSD is cleared with a half-life of about 2.6 h while its subjective effects run 8–12 h.
No half-life is published for this compound in the sources this site reads.
Primary pharmacological drivers
ChEMBL holds no curated mechanism-of-action record for this compound. The measured affinities below are the evidence this archive has for what it binds.
Mechanism, as published
Quoted verbatim from the database named after each passage, never summarized.
Three psychological active principles from the seeds of Peganum harmala L., harmine, harmaline and harmalol, showed vasorelaxant activities in isolated rat thoracic aorta preparations precontracted by phenylephrine or KCl with rank order of relaxation potency of harmine > harmaline > harmalol. The vasorelaxant effects of harmine and harma…
Hazardous Substances Data Bank (HSDB)PMID 11325023Shi CC et al; Jpn J Pharmacol 85 (3): 299-305 (2001)
IV · Clinical
Clinical description
Where this compound's substance class sits in ICD-11 and DSM-5-TR, and how much of the recorded literature speaks to each domain of a mental status examination.
Filed under Central Nervous System Stimulants
- 6C46Disorders due to use of stimulants including amphetamines, methamphetamine or methcathinone
Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision (DSM-5-TR): Stimulant-Related Disorders. Category names only — the manual is in copyright and no diagnostic criterion is reproduced here.
How much has been written about each domain
The clinical domains, and how many of the records this archive holds for this compound say something under each. What the terms mean, and the word list behind every spoke, are set out in the method.
- Perception 1
- matched on “hallucinogen” · in PMID 18803088
- Psychomotor activity 1
- matched on “sedat” · in PMID 18803088
V · Systems
Systems physiology
Where the targets this compound binds are transcribed — brain regions on the left, peripheral and autonomic tissues on the right. A join of two measurements, not a claim about what the compound does to either.
Brain
basal ganglia: drawn as the caudate nucleus, putamen and globus pallidus.
Measured but not drawn — this anatomogram has no outline for them: midbrain 47.7, retina 25.7, pituitary gland 18.6, spinal cord 14.4.
Body
Square-root ramp · shared scale across both plates
Shading is transcript level — not affinity, and not affinity combined with expression. Outlined but unshaded organs hold none of this compound’s resolved targets above the atlas’s detection threshold. Anatomy from EMBL-EBI Anatomogram (Apache License 2.0); regions identified by Uberon (uberon.org), CC BY 3.0.
Brain regions
Regions where this compound's measured targets are transcribed. Linked from the plate above.
hypothalamus
103.9 nTPMcerebellum
59.1 nTPMmidbrain
47.7 nTPMbasal ganglia
38.3 nTPMretina
25.7 nTPMcerebral cortex
23.4 nTPMamygdala
21.5 nTPMpituitary gland
18.6 nTPMhippocampal formation
16.5 nTPMspinal cord
14.4 nTPM
Peripheral & autonomic
Tissues outside the CNS expressing the same targets — where a compound's bodily effects become possible.
liver
386.2 nTPMsmall intestine
206.3 nTPMskeletal muscle
152.9 nTPMduodenum
143.7 nTPMthyroid gland
105.7 nTPMcolon
104.7 nTPMkidney
69.7 nTPMsalivary gland
66.9 nTPMurinary bladder
61.9 nTPMlung
56.9 nTPMstomach 1
50.0 nTPMheart muscle
44.8 nTPMpancreas
35.0 nTPMspleen
28.6 nTPMadrenal gland
24.9 nTPMsmooth muscle
22.5 nTPM
Each row joins two published measurements and nothing else: the affinity this archive holds for the compound at that target, and the transcript level the Human Protein Atlas reports for that target’s gene in that region. Bars scale with expression only. Expression is not activation — a receptor transcribed in a region is a receptor available to be bound there, which is a weaker and more defensible claim than saying the region is affected.
1 of this compound’s targets could not be resolved to a gene and are absent from both columns: CAAX prenyl protease 1.
Expression data from Human Protein Atlas (CC BY-SA 3.0), RNA expression, nTPM (normalized transcripts per million), consensus tissue dataset. Uhlén M, et al. Tissue-based map of the human proteome. Science. 2015;347(6220):1260419.
VI · Profile
Affinity rosette
The strongest measurement at each of 6 molecular targets. Cell-line and whole-organism screens are excluded here — they carry no affinity — and appear in the table below.
VII · Toxicology
Toxicological profile
What has been measured, and what has been published — kept apart, and neither scored. There is no risk rating on this page; the archive once carried one, identical for every compound, produced by a stub.
Measured in this archive
Assays that bear on toxicity, drawn from the same ChEMBL records as everything else on this page. They are measurements of what a compound binds or does to cells — not verdicts about what it does to a person.
Cytochrome P450 inhibition 1
Inhibition of a drug-metabolising enzyme, which is how interactions arise — the harmala alkaloids' MAO inhibition is the same kind of fact, and appears with the measurements above.
- Cytochrome P450 2D6Potency3,981nMCHEMBL1614110
As published
Quoted verbatim from the database named after each passage, never summarized — a summary of a toxicology statement is a new claim.
Human Toxicity Excerpts
/CASE REPORTS/ Peganum harmala, commonly called "Syrian rue," is native to countries around the Mediterranean sea and western United States. Known for its sedative effects when consumed by farm animals, its seeds have stimulant and hallucinogenic effects at low doses (3-4 g when eaten) in humans. Its active ingredients harmaline and harmine have monoamine oxidase inhibitor properties. A 41-year-old female prepared a…
Hazardous Substances Data Bank (HSDB)PMID 18803088Yuruktumen A et al; Clin Toxicol (Phila) 46 (8): 749-52 (2008)
Published passages via PubChem toxicology sections, aggregating Hazardous Substances Data Bank (HSDB), RTECS, LiverTox. No figure on this page is scored, ranked or combined into a risk level.
VIII · Evidence
Every measurement
One row per published value. The identifier in the last column resolves to the ChEMBL assay record it was read from.
Equilibrium binding constants 1
Ki and Kd — a concentration at equilibrium. Directly comparable across rows at the same target.
| Target | Class | Type | Value (nM) | pX | Organism | Assay |
|---|---|---|---|---|---|---|
| 5-HT6 | Serotonin receptors | Ki | 1,500 | 5.82 | Homo sapiens | CHEMBL5235598 |
Functional readouts 8
IC₅₀, EC₅₀, AC₅₀ and potency. Assay-dependent, and not interchangeable with a binding constant.
| Target | Class | Type | Value (nM) | pX | Organism | Assay |
|---|---|---|---|---|---|---|
| Amine oxidase [flavin-containing] A | Enzymes | IC50 | 2.50 | 8.60 | Homo sapiens | CHEMBL5235559 |
| Amine oxidase [flavin-containing] A | Enzymes | IC50 | 12.00 | 7.92 | Rattus norvegicus | CHEMBL733230 |
| Dual specificity tyrosine-phosphorylation-regulated kinase 1A | Enzymes | AC50 | 1,236 | 5.91 | Rattus norvegicus | CHEMBL1794557 |
| CAAX prenyl protease 1 | Enzymes | AC50 | 2,766 | 5.56 | Saccharomyces cerevisiae S288c | CHEMBL1738635 |
| Cytochrome P450 2D6 | Enzymes | Potency | 3,981 | 5.40 | Homo sapiens | CHEMBL1614110 |
| Dual specificity tyrosine-phosphorylation-regulated kinase 1A | Enzymes | IC50 | 4,600 | 5.34 | Homo sapiens | CHEMBL5235544 |
| Acetylcholinesterase | Enzymes | IC50 | 4,900 | 5.31 | Electrophorus electricus | CHEMBL2020010 |
| Acetylcholinesterase | Enzymes | IC50 | 23,700 | 4.63 | Homo sapiens | CHEMBL2020014 |
- P
- PubChem
- C
- ChEMBL
- R
- Computed here with RDKit
- D
- Derived here from the stored measurement
IX · Trials
Registered clinical trials
Studies filed with ClinicalTrials.gov that name this compound as an intervention. A registered trial is a protocol, not a result — status and enrollment are printed beside every row, and withdrawn studies are counted rather than hidden.
— No registered study names Harmaline as an intervention. That is an absence of registered research, not evidence about the compound. Most of this archive has never been the subject of a registered trial.
Records from ClinicalTrials.gov (U.S. National Library of Medicine, NIH), API v2. A study is listed against a compound only when a verified name for that compound appears as a whole word in one of the study's own intervention names. A short code must appear as written, and a name the registry uses for something else (Aleph, a vaccine maker) is not matched. Title matches are not accepted. The matched name and the intervention text it matched are shown with every row.
Searched as Harmaline · Dihydroharmine · 3,4-Dihydroharmine. Run this search at the registry.
A registered trial is a protocol somebody filed with the registry. It is not a result, and nothing on this plate says whether Harmaline worked.
X · Legal
Controlled-substance status
United States federal scheduling, read from the DEA records this archive holds. Not legal advice, and an absent record is not a finding that a compound is uncontrolled.
An absent DEA record is not a finding that Harmaline is legal. It means this archive holds no DEA passage for it. The Controlled Substances Analogue Enforcement Act reaches substances that appear on no schedule by name, and many compounds here are ring-substituted analogues of scheduled drugs. Nothing on this plate should be read as saying a compound may lawfully be made, held or supplied.
United States federal status only. State law differs, and so does the law of every other country — none of it is represented here. Scheduling changes, and this reflects the DEA records held by PubChem descriptive sections when the monograph was last harvested, not necessarily today. This is a record of what a database publishes, not legal advice.
XI · Literature
Sources behind this dossier
The papers this compound's values were read from, ranked by what each contributed. Not a review of the field.
Every paper below is one some value on this page came from — a binding constant, a passage of pharmacology or toxicology, or a measured duration. Each entry says what this archive took from it. Nothing else is claimed about any of them: the title is the study’s own account of itself, and a summary written here would be an assertion with no source behind it.
- 01
Syrian rue tea: a recipe for disaster
Yuruktumen A, Karaduman S, Bengi F et al. · Clinical toxicology (Philadelphia, Pa.) 2008
- · Human Toxicity Excerpts
- 02
Comparative study on the vasorelaxant effects of three harmala alkaloids in vitro
Shi CC, Liao JF, Chen CF · Japanese journal of pharmacology 2001
- · Mechanism of Action