Rhynchophylline (Oxindole Alkaloid · Antihypertensive · NMDA Antagonist)
| Compound | Rhynchophylline |
| Chemical class | Alkaloid — Indole (Tetracyclic Oxindole Alkaloid) |
| CAS | 76-66-4 |
| Primary source | Uncaria rhynchophylla (Gou Teng / cat claw vine), Uncaria tomentosa (cat’s claw) |
| Key applications | Neuroprotective, antihypertensive, anti-arrhythmic, cardiovascular |
| Claim strength | Moderate |
| Typical form | Uncaria rhynchophylla hook extract; Gou Teng standardised extract |
| Buy from Herbuno | Contact Herbuno for sourcing enquiries → |
Commercial source: Rhynchophylline is commercially available as a constituent of Uncaria rhynchophylla (Gou Teng) hook extract from specialist Chinese botanical suppliers, and as a research-grade isolated compound from specialist chemical suppliers. Uncaria gambir (gambier, the source of Herbuno’s Uncaria-derived catechin and tannin extracts) is a different species in the same genus and contains rhynchophylline at lower concentrations than U. rhynchophylla. Contact Herbuno for Gou Teng extract availability. Traditional use: Gou Teng (Uncaria rhynchophylla hooks and stems) is a major TCM herb used for over 1,500 years for headache, hypertension, eclampsia of pregnancy, infantile convulsions, and as a calming/sedative herb for wind-heat conditions. It is classified as a liver-calming herb in TCM pharmacopoeia. Rhynchophylline and isorhynchophylline are the primary alkaloids responsible for the antihypertensive and neurological activities. Research trajectory: Rhynchophylline has a well-developed evidence base from Chinese research for antihypertensive (NMDA receptor antagonism, calcium channel antagonism), neuroprotective (amyloid-beta inhibition, NLRP3 suppression), and anti-arrhythmic mechanisms. It is considered one of the primary Kampo/TCM neuroprotective alkaloids. See sourcing options below.
Evidence for Rhynchophylline Applications
Antihypertensive: Rhynchophylline produces antihypertensive effects via NMDA receptor antagonism (reducing sympathetic outflow), calcium channel antagonism (vascular smooth muscle relaxation), and eNOS activation (NO-mediated vasodilation). Multiple Chinese human studies of Gou Teng preparations demonstrate significant blood pressure reduction in hypertensive patients, with meta-analyses supporting Kampo (Japanese traditional medicine) Chotosan formula (Gou Teng-containing) for hypertension. Claim strength: Moderate.
Neuroprotective — NMDA antagonism and amyloid inhibition: Rhynchophylline inhibits NMDA receptors (the same mechanism as memantine, an Alzheimer’s pharmaceutical), reducing glutamate excitotoxicity. It also inhibits amyloid-beta aggregation, reduces NLRP3 neuroinflammation, and promotes neuronal survival in stroke and Alzheimer’s animal models. This dual antihypertensive/neuroprotective profile is clinically relevant for elderly vascular cognitive impairment. Claim strength: Moderate.
Anti-arrhythmic: Rhynchophylline blocks hERG potassium channels and sodium channels in cardiac electrophysiology, producing antiarrhythmic effects in atrial and ventricular arrhythmia models. This cardiac activity may contribute to Gou Teng’s cardiovascular traditional applications. Claim strength: Moderate.
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Dosage & Formulator Specification
TCM Gou Teng dose: 6–12 g/day dried hooks as decoction. Note: Gou Teng is specifically the hooks (stem hooks) of Uncaria rhynchophylla, not the leaves or root — the alkaloid content is highest in hooks. For standardised extract: 300–600 mg/day Gou Teng hook extract (standardised to minimum 0.5–1% rhynchophylline + isorhynchophylline by HPLC) for antihypertensive and neuroprotective applications. Japanese Kampo Chotosan formula context uses standardised mixed herb preparations at higher extract equivalent doses.
Specify Uncaria rhynchophylla hook extract for rhynchophylline-targeted formulations — distinguish from Uncaria gambir (gambier, used for catechin/tannin extracts with minimal alkaloid content) and Uncaria tomentosa (South American cat’s claw, containing different oxindole alkaloids including mitraphylline, isopteropodine — with immunomodulatory rather than antihypertensive/neuroprotective profile). These are three different Uncaria species with different primary bioactives.
Important: rhynchophylline’s hERG channel blocking activity theoretically risks QT prolongation at higher doses — include cardiac advisory language for individuals on QT-prolonging medications. Gou Teng decoctions are traditionally heated briefly (added at end of decoction) because prolonged heating degrades alkaloid content; similar considerations apply to high-temperature extract processing.
Frequently Asked Questions — Rhynchophylline
Is Uncaria rhynchophylla (Gou Teng) the same as Uncaria tomentosa (cat’s claw)?
No — they are different species in the same genus with significantly different phytochemical and pharmacological profiles. Uncaria rhynchophylla (Gou Teng) is the East Asian species used in TCM and Kampo, with antihypertensive and neuroprotective alkaloids (rhynchophylline, isorhynchophylline). Uncaria tomentosa (South American cat’s claw) is the Amazonian species used in traditional South American medicine, primarily for immunomodulatory and anti-inflammatory applications, containing different alkaloids (pentacyclic oxindoles including mitraphylline). They should not be substituted for each other in formulations.
Is rhynchophylline similar to memantine in mechanism?
Yes — rhynchophylline is an NMDA receptor antagonist with similar mechanistic action to memantine (an Alzheimer’s pharmaceutical). Both reduce glutamate excitotoxicity by blocking NMDA receptor-mediated calcium influx. Rhynchophylline’s additional calcium channel and hERG channel activities provide a broader cardiovascular-neurological pharmacological profile than memantine, which is specifically NMDA-targeted. The mechanistic parallel supports rhynchophylline’s research interest for vascular cognitive impairment.
Can Gou Teng extract be used in a hypertension supplement formulation?
Yes — with the caveat that hypertension management warrants medical supervision and supplements should not be positioned as replacements for pharmaceutical antihypertensive therapy. For individuals with borderline or pre-hypertensive readings seeking dietary support alongside lifestyle modifications, Gou Teng extract has supporting evidence. Co-formulation with hibiscus extract (ACE inhibitory), olive leaf extract (oleuropein, antihypertensive), and magnesium provides a multi-mechanism botanical antihypertensive blend.
Why is Uncaria gambir (Herbuno’s Uncaria product) different from Gou Teng?
Uncaria gambir (gambier) is used commercially for its catechin and tannin content — it is the source of commercial catechin extracts and gambir tannin (used in leather tanning and as an astringent). Its alkaloid content is minimal and rhynchophylline is not a primary constituent. The Herbuno Uncaria gambir catechin and tannin extracts are appropriate for antioxidant and astringent applications, not for the antihypertensive or neuroprotective rhynchophylline applications, which require U. rhynchophylla specifically.
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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