Harmaline (Dihydro-Beta-Carboline · MAO-A Inhibitor · Tremor Research)

Compound	Harmaline
Chemical class	Alkaloid — Indole (Dihydro-β-Carboline; Harmala Alkaloid)
CAS	304-21-2
Primary source	Peganum harmala (Syrian rue), Banisteriopsis caapi (ayahuasca vine)
Key applications	MAO-A inhibitor, tremor modulation (essential tremor), antidepressant research
Claim strength	Moderate
Typical form	Peganum harmala seed extract co-constituent with harmine
Buy from Herbuno	Harmal Seed Extract Powder - Peganum harmala → Harmal Oil Soluble Extract - Peganum harmala →

Commercial source: Peganum harmala (harmal) seed extract is commercially available, with harmaline as a significant co-alkaloid alongside harmine. See sourcing options below. Traditional use: Shares Peganum harmala’s traditional use across North Africa, Middle East, and Central Asia, where both harmine and harmaline are co-present in harmal seed preparations. Harmaline was not individually distinguished in traditional practice. In South American ayahuasca traditions, the combined harmine/harmaline/tetrahydroharmine fraction of Banisteriopsis caapi provides the MAO inhibitory component that enables oral DMT activity. Research trajectory: Harmaline has attracted specific research for essential tremor management — it paradoxically induces tremor at high doses in animals (via olivocerebellar pathway modulation) while reducing tremor at lower doses, providing insights into essential tremor pathophysiology. Additionally, harmaline shares harmine’s MAO-A inhibitory and neuroprotective mechanisms, with some differentiation due to its dihydro (partially reduced) structure. See sourcing options below.

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Evidence for Harmaline Applications

MAO-A inhibition and serotonergic effects: Harmaline is a reversible MAO-A inhibitor comparable in potency to harmine. The combination of harmine + harmaline in Peganum harmala extract provides combined MAO-A inhibitory activity. The same drug interaction considerations (tyramine, serotonergic medications) apply to harmaline as to harmine. Claim strength: Moderate.

Essential tremor research: Harmaline-induced tremor in rodents (via inferior olivary nucleus synchronisation) is a validated animal model of essential tremor. This has been used to study the neuroscience of essential tremor and test potential treatments. At sub-tremorigenic doses, harmaline modulates olivocerebellar pathway activity. This dual dose-dependent effect (tremor-inducing at high dose, modulating at low dose) makes harmaline pharmacologically interesting but dosing precision critical. Claim strength: Moderate (model-relevant; complex dose-response).

Neuroprotective and antidepressant: Harmaline shares harmine’s neurogenesis-promoting and anti-inflammatory neuroprotective mechanisms. MAO-A inhibition produces antidepressant effects in animal models. Human antidepressant clinical data for isolated harmaline are absent. Claim strength: Moderate.

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Dosage & Formulator Specification

Harmaline is co-present with harmine in Peganum harmala extract at approximately 30–50% of total harmala alkaloids (harmine being the other 50–70%). The same drug interaction advisory language as harmine applies in full to harmaline-containing preparations. For Peganum harmala extract formulations, specify combined harmine + harmaline content by HPLC and maintain total harmala alkaloid dose at levels with acceptable MAO-A inhibitory risk profile. Include the comprehensive drug interaction warning required for MAO inhibitory preparations on all product labels.

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Frequently Asked Questions — Harmaline

What is the structural difference between harmine and harmaline?
Harmaline is the dihydro analogue of harmine — the C-3/C-4 double bond in harmine’s pyridine ring is reduced to a single bond in harmaline. This makes harmaline a 3,4-dihydro-β-carboline versus harmine’s fully aromatic β-carboline. The partial reduction slightly alters metabolic handling and receptor binding geometry. Both are MAO-A inhibitors; harmaline is considered slightly less selective for MAO-A versus MAO-B than harmine.

Why does harmaline induce tremor at high doses?
Harmaline synchronises the olivocerebellar pathway (inferior olive → Purkinje cells → cerebellar nuclei) at 8–12 Hz — the same frequency as essential tremor. This is caused by harmaline’s modulation of gap junction and oscillatory behaviour in inferior olivary neurons. The mechanism has made harmaline-induced tremor the primary pharmacological model for essential tremor research. At lower sub-tremorigenic doses, harmaline modulates rather than synchronises this pathway.

Is harmaline more potent than harmine?
For MAO-A inhibition, harmine and harmaline are broadly comparable in potency (Ki values in low nanomolar range). Harmaline has slightly lower selectivity for MAO-A over MAO-B compared to harmine. For the tremor-inducing activity, harmaline is more potent than harmine (harmine does not reliably induce harmaline-type tremor in animals at comparable doses), attributed to the different pharmacokinetic profile and CNS distribution of the dihydro structure.

Are harmine and harmaline both present in ayahuasca?
Yes — Banisteriopsis caapi vine (the “MAOI component” of ayahuasca) contains harmine, harmaline, and tetrahydroharmine as the primary beta-carboline alkaloids. Their combined MAO-A inhibitory activity prevents DMT (from Psychotria viridis or other admixture plants) from being degraded in the GI tract and liver, allowing it to reach the brain. The three alkaloids contribute complementary MAO-A inhibitory activity with different duration profiles.

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Claim-strength scale – High = multiple human RCTs; Moderate = limited trials or strong preclinical convergence; Emerging = early-stage lab or animal data.

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