Tetrahydroalstonine (Heteroyohimbine Indole Alkaloid · Alpha-Adrenergic)

Compound	Tetrahydroalstonine
Chemical class	Alkaloid — Indole (heteroyohimbine; reduced alstonine; ajmalicine stereoisomer)
CAS	6474-90-4
Primary source	Alstonia spp.; also Catharanthus roseus, Rauwolfia spp., Uncaria spp.
Key applications	Alpha-2 adrenergic activity; heteroyohimbine reference compound
Claim strength	Emerging
Typical form	Alstonia extract standardised to total indole alkaloids (availability on request)
Buy from Herbuno	Availability on request — request bulk pricing →

Name origin: Tetrahydroalstonine is the fully reduced (tetrahydro) counterpart of alstonine, and its name records that relationship directly. It is a heteroyohimbine-type monoterpenoid indole alkaloid, closely related to ajmalicine (raubasine) — indeed the older pharmacological literature treats it as a raubasine stereoisomer — and it sits in the same biosynthetic branch as serpentine and alstonine, the anhydronium alkaloids to which the reduced heteroyohimbines correspond. Traditional use: Tetrahydroalstonine has no independent traditional identity. It occurs across a wide range of medicinal Apocynaceae — Alstonia, Catharanthus, Rauwolfia, and Uncaria among them — and it is delivered incidentally within the traditional preparations of those plants, which include the West African Alstonia barks and the Ayurvedic Saptaparna. Research trajectory: Its best-characterised pharmacology is adrenergic. Work on the alpha-adrenoceptor interactions of the heteroyohimbines established that raubasine, tetrahydroalstonine, and akuammigine inhibit sympathetic stimulation and adrenaline-induced hypertension, and that this activity shows specificity for presynaptic alpha-2 adrenergic receptors Elisabetsky 2006. The alkaloid is documented among the constituents of Alstonia in reviews of the genus's phytochemistry and pharmacology Adotey 2012. This adrenergic profile connects it structurally and functionally to yohimbine, the archetypal alpha-2 antagonist, though the heteroyohimbines differ in their receptor selectivity and potency. Commercial source: Alstonia extract standardised to total indole alkaloids is available from Herbuno on request.

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Evidence for Tetrahydroalstonine Applications

Alpha-2 adrenergic activity: Raubasine, tetrahydroalstonine, and akuammigine were shown to inhibit sympathetic stimulation and adrenaline-induced hypertension, with the pharmacology demonstrating specificity for presynaptic alpha-2 adrenergic receptors Elisabetsky 2006. This is the alkaloid's best-defined activity and the basis of most interest in it. Claim strength: Emerging.

Relationship to ajmalicine: The alpha-adrenoceptor interactions of tetrahydroalstonine have been studied comparatively against raubasine stereoisomers, work that mapped the pre- and postsynaptic adrenoceptor effects across this closely related group Elisabetsky 2006. Its similarity to ajmalicine is close enough that the two are often discussed together. Claim strength: Emerging.

Alstonia constituent: Tetrahydroalstonine is documented among the alkaloids isolated from Alstonia species in reviews of the genus, sitting alongside echitamine, echitamidine, picrinine, and akuammicine within a complex bark alkaloid profile Adotey 2012. Claim strength: Emerging.

Cross-genus occurrence: The alkaloid is found across Alstonia, Catharanthus, Rauwolfia, and Uncaria, a distribution that reflects the shared heteroyohimbine branch of monoterpenoid indole alkaloid biosynthesis in the Apocynaceae and Rubiaceae and means it is encountered in material sourced for many different purposes. Claim strength: Emerging.

Oxidation-state relationship: As the reduced counterpart of alstonine, tetrahydroalstonine illustrates the same saturated-versus-aromatic pairing seen between ajmalicine and serpentine, and tracking the balance between the reduced and anhydronium forms is informative about the redox state of the alkaloid pathway in a given tissue. Claim strength: Emerging.

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Dosage & Formulator Specification

Tetrahydroalstonine is at an early, preclinical stage of evidence, and no established human dose exists. Its adrenergic pharmacology is drawn from isolated-tissue and animal work, and those exposures do not translate to supplement dosing; they are cited for scientific context only.

The adrenergic activity carries a direct labelling implication. Because tetrahydroalstonine acts at presynaptic alpha-2 adrenoceptors and inhibits adrenaline-induced pressor responses, any material delivering it has a plausible cardiovascular and sympathetic-interaction profile, and responsible formulation should reflect the early evidence base and avoid therapeutic claims. This is the same receptor family engaged by yohimbine, a compound whose supplement use has attracted substantial regulatory concern, so the adrenergic territory demands particular care.

For material specification, the practical input is Alstonia extract standardised to total indole alkaloids by HPLC. Because tetrahydroalstonine also occurs in Catharanthus, Rauwolfia, and Uncaria, the source species must be specified rather than assumed — and several of those alternatives carry their own potent regulated alkaloids, so tetrahydroalstonine content alone is a poor guide to a material's overall character. Alstonia extract standardised to total alkaloids is available from Herbuno on request.

Tetrahydroalstonine also illustrates a recurring pattern worth naming: the reduced and oxidised forms of a heteroyohimbine can differ substantially in properties while remaining a single biosynthetic pair. Tetrahydroalstonine and alstonine, like ajmalicine and serpentine, are related by oxidation state alone, yet the reduced member carries the adrenergic activity while the aromatic anhydronium member shows an entirely different behavioural profile. For anyone characterising Apocynaceae material, this means the oxidation state of the alkaloid fraction is not a trivial analytical detail but a determinant of what the material actually does.

This monograph documents tetrahydroalstonine as a formulator reference within the HerbIQ index, connecting it to alstonine and echitamine alongside it and to the wider heteroyohimbine group (serpentine, ajmalicine, yohimbine) covered elsewhere, and positions it honestly as an early-evidence compound available on request.

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Frequently Asked Questions — Tetrahydroalstonine

What is tetrahydroalstonine?
Tetrahydroalstonine is a heteroyohimbine-type indole alkaloid found in Alstonia, Catharanthus, Rauwolfia, and related Apocynaceae. It is the reduced counterpart of alstonine and a close structural relative of ajmalicine (raubasine), with which it shares alpha-adrenergic activity.

What is tetrahydroalstonine studied for?
Its best-characterised activity is at alpha-adrenergic receptors. Tetrahydroalstonine, together with raubasine and akuammigine, has been shown to inhibit sympathetic stimulation and adrenaline-induced hypertension with specificity for presynaptic alpha-2 adrenergic receptors. The evidence is preclinical.

Can I source tetrahydroalstonine from Herbuno?
Alstonia extract standardised to total indole alkaloids is available on request. Herbuno does not currently stock a tetrahydroalstonine-standardised product, so specification and bulk pricing would be arranged on enquiry.

How does tetrahydroalstonine relate to ajmalicine?
They are closely related heteroyohimbine stereoisomers, and their alpha-adrenergic pharmacology has been studied comparatively. Both act at alpha-adrenoceptors with presynaptic alpha-2 specificity, and tetrahydroalstonine is sometimes described as a stereoisomer of raubasine (ajmalicine) in the older pharmacological literature.

Related compounds: Alstonine, Echitamine, Serpentine, Yohimbine

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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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