Cat's Claw

Uncaria tomentosa

Family: Rubiaceae Part used: Inner bark, root bark

Key Compounds

• Pentacyclic oxindole alkaloids (POA)
• Uncarine A, B, C, D, E, F
• Mitraphylline
• Isomitraphylline
• Speciophylline
• Tetracyclic oxindole alkaloids (TOA)
• Rhynchophylline
• Isorhynchophylline
• Quinovic acid glycosides
• Chlorogenic acid
• Rutin
• Quercetin
• Kaempferol
• Beta-sitosterol

Traditional Use

• Immunomodulation — pentacyclic oxindole alkaloids (POAs) enhance phagocytosis and granulocyte function; multiple in vitro and animal studies support immune stimulation; human clinical studies are limited but consistent with the laboratory evidence; traditional Ashaninka use for general immune support and infection has approximately 2,000 years of documentation
• Anti-inflammatory — quinovic acid glycosides inhibit COX-1 and COX-2; clinical trials for rheumatoid arthritis and osteoarthritis show significant reduction in pain scores; the 2002 Mur et al. RCT (52 RA patients) showed significant reduction in joint pain versus placebo
• DNA repair stimulation — in vitro and ex vivo studies show that POA alkaloids stimulate DNA repair enzymes; some researchers have proposed cancer-adjunct applications on this basis; evidence is preliminary and clinical application has not been established
• Ashaninka traditional medicine — the Ashaninka people of Peru have used cat's claw (*uña de gato*) as a primary medicine for at least 2,000 years; uses included inflammation, digestive complaints, infections, arthritis, and as a general tonic; the plant is sacred in some Ashaninka ritual contexts
• Peruvian regulated export — Peru established the world's first national regulations specifically for cat's claw in 1999 (Supreme Decree 007); the regulations require sustainable harvest leaving 30 cm of root for regeneration; cat's claw is a major botanical export earner for Peru
• Gastric protective — traditional and laboratory evidence for gastric mucosal protection; used in Peruvian folk medicine for gastritis, ulcers, and digestive inflammation; quinovic acid glycosides and alkaloids contribute to this effect

The thorns are curved and they look like cat claws. This is what the plant is called in every language that named it.

Uña de gato in Spanish — cat’s nail. Cat’s claw in English. Uncaria from Latin uncus, hook. The naming pattern is consistent across independent encounters with the vine. The thorns are not unusual in the Amazonian forest, but they are unusual in shape: curved, like a cat’s retracted claw rather than a straight thorn. The vine uses them to climb.

The Ashaninka people of Peru used the bark and root bark of this vine as one of their most important medicines for at least two thousand years. The plants they were using had the same alkaloids as the plants that were studied in European laboratories in the 1970s and in clinical trials in the 1990s.

Meet the plant

A large woody vine of the Peruvian Amazon and surrounding regions. Climbs to 30 metres. The curved thorns are the identification feature — and also how the plant reaches the canopy light in a dense forest.

The inner bark is the primary medicinal part. It is harvested from the vine itself without killing the plant; the bark regenerates. Root bark has higher alkaloid content but harvesting the root kills the plant.

The alkaloid question

Cat’s claw’s inner bark contains two classes of oxindole alkaloids:

Pentacyclic oxindole alkaloids (POAs): mitraphylline, uncarine A/B/C/D/E/F, speciophylline. These have immunomodulatory activity — stimulating phagocytosis and immune function.

Tetracyclic oxindole alkaloids (TOAs): rhynchophylline, isorhynchophylline. These have CNS effects in high doses.

In the 1990s, some Austrian researchers and supplement companies promoted the idea that TOAs block POA activity, creating a market for ‘TOA-free’ products sold at premium prices. This became a substantial commercial story.

The clinical trials that established cat’s claw’s efficacy — for arthritis, for immune function — used whole bark preparations containing both alkaloid types. The ‘TOA-free’ products have no superior clinical evidence over whole bark preparations. The two chemotypes naturally coexist in the bark; the separation was a marketing initiative, not a clinical finding.

The Ashaninka knowledge

The Ashaninka, an indigenous Amazonian people whose territory spans Peru and Brazil, used cat’s claw as one of their primary medicines. Uses included inflammatory conditions, arthritis, digestive complaints, infections, and general immune support. The plant has cultural and sometimes ritual significance in some Ashaninka communities.

This knowledge was the starting point for the Austrian research in the 1970s. Dr. Helmut Keplinger and colleagues collected the plant and began isolation work that led to the first European publications and subsequently to clinical interest.

The question of benefit from commercial exploitation of indigenous plant knowledge is ongoing and unresolved in the cat’s claw case, as in most cases where Amazonian plant medicines have become international supplement categories.

The arthritis evidence

The 2002 Mur et al. RCT (Journal of Rheumatology): 52 rheumatoid arthritis patients, cat’s claw extract versus placebo over 24 weeks. Significant reduction in painful and swollen joints in the treatment group. A 2001 Piscoya et al. trial for osteoarthritis found significant pain reduction versus placebo.

These are small trials. The anti-inflammatory mechanism — quinovic acid glycoside inhibition of COX-1 and COX-2 — is established in cell studies. The clinical evidence exists but is not extensive.

German Commission E has not approved cat’s claw due to insufficient clinical data. The Commission requires larger and better-controlled trials than currently exist.

What people actually do with it

Bark tea (traditional method): Simmer 1–2 grams of dried inner bark in 250ml water for 15–20 minutes, strain. 1–3 cups daily. The traditional Ashaninka preparation method.

Standardised extract: 500–1000 mg daily in capsule form. Used in clinical trials. More consistent alkaloid content than bulk bark.

Tincture: 2–4 mL, 2–3 times daily.

Typical course: 4–8 weeks for immune or anti-inflammatory applications. Not for continuous long-term use.

Caution: Avoid in autoimmune conditions (immune stimulation is contraindicated), during pregnancy, and with immunosuppressant drugs.

Could you grow this yourself?

Only in tropical or subtropical conditions — the plant is Amazonian and requires heat and humidity. It is not suitable for temperate gardens.

Cat’s claw (ネコの爪) in Japan

Japanese traditional medicine uses a different Uncaria species — 釣藤鉤 (chōtōkō, U. rhynchophylla) — in kampo formulations for hypertension and neurological conditions. This is a different plant from the Amazonian cat’s claw, though in the same genus, and has different applications.

Western cat’s claw supplements (ネコの爪, ウンカリア) are available in Japanese supplement retail positioned for immune support and joint health. There is no classical Japanese medicinal relationship with U. tomentosa. Consumer interest aligns with the same immune-support and anti-inflammatory categories that drive European and North American sales.

Things you’re probably wondering

Is the TOA-free product better? The clinical evidence was established using whole bark containing both POAs and TOAs. TOA-free products have no superior clinical evidence over whole bark. The distinction was primarily a marketing development, not a clinical finding.

How does it connect to Japanese medicine? The genus Uncaria includes 釣藤鉤 (U. rhynchophylla) — a Japanese Pharmacopoeia drug used in kampo for hypertension and neurological conditions. Different species, different alkaloids, different application. The genus is shared.

Is it sustainable to harvest? Peru regulated cat’s claw harvest in 1999, requiring vine-only harvest leaving roots intact for regeneration. Bark from vines (not roots) allows the plant to survive.

Botanical details

The full compound list

See Also

• Astragalus — immune tonic herb with stronger clinical evidence; different mechanism
• Echinacea — shorter-duration immune support; different chemistry
• Boswellia — anti-inflammatory with stronger arthritis clinical evidence

References

• Mur, E. et al. (2002). Randomized double blind trial of an extract from Uncaria tomentosa for the treatment of rheumatoid arthritis. Journal of Rheumatology, 29(4), 678–681.
• Piscoya, J. et al. (2001). Efficacy and safety of freeze-dried cat’s claw in osteoarthritis. Inflammation Research, 50(9), 442–448.
• Heitzman, M.E. et al. (2005). Ethnobotany, phytochemistry and pharmacology of Uncaria (Rubiaceae). Phytochemistry, 66(1), 5–29.
• Sandoval, M. et al. (2002). Cat’s claw inhibits TNFα production and scavenges free radicals. Free Radical Biology and Medicine, 29(1), 71–78.