Cat's claw

Uncaria tomentosa

Cat's claw is widely used by indigenous healers in South America. The Ashaninka Indians of Peru regard it as a powerful "health-restorative" medicine and use it to treat inflammatory, infectious and cancerous diseases. Cat's claw has recently been adopted into the western pharmacopeia and is marketed primarily as a preventive medicine and as an alternative treatment for cancer, HIV and other infections, and inflammatory diseases such as arthritis, asthma and ulcers.

Published human evidence supporting the use of cat's claw in arthritis and HIV is based on unblinded trials, case reports and traditional knowledge. Extensive animal and in vitro evidence indicates that cat's claw exerts significant anti-inflammatory, antimutagenic, antineoplastic and antioxidant effects, but the mechanisms are still not clearly understood. The evidence to date suggests that cat's claw is a reasonably safe herb with low toxicity. However, it is contraindicated in some subpopulations and may exert mild side effects, most frequently intermittent diarrhea or constipation. Several factors may limit the potential efficacy of commercial products. Some findings suggest that qualitative and quantitative differences in the alkaloid content may have a significant impact on both safety and efficacy, but no evidence of clinical relevance has been published, and this hypothesis remains controversial.

Other names

• Garabato
• Saventaro
• Una De Gato

Parts used

Bark, root, leaves.

Uses

The data presented here are for aqueous-alcoholic extracts at dosages equivalent to 80 - 240 mg/day.

In a placebo-controlled trial (24 subjects, 40-day study period) and a case study (2 subjects, 15-day study period) cat's claw abolished the mutagenicity of smoker's urine.

On the basis of evidence from unblinded trials and case studies, cat's claw is being used clinically in Europe as an adjunct to conventional therapies for brain tumors, especially ependymoblastoma and astrocytoma, to maintain remission (study with 78 patients over 19 months), to maintain remission, arrest growth and lessen side effects of conventional therapeutics (study with 53 patients, followed up for 9 years), and in the treatment of leukemia, glioma, adenocarcinoma, testicular teratoma, cervical carcinoma, melanoma and medulloblastoma.

Cat's claw has been used as an adjunct to zidovudine (AZT), to maintain CD4 counts in asymptomatic HIV patients and to improve counts in symptomatic patients (30-month study with 14 patients).

In a 5 - month study of 13 HIV patients who refused conventional therapy, cat's claw normalized lymphocyte counts and decreased the occurrence of opportunistic infections (e.g., recurrent herpes simplex and fungal infections).

Cat's claw has also been used to prevent and ameliorate symptomatic outbreaks of herpes virus.

Cat's claw has anti-inflammatory activity in arthritis, alone and as an adjunct to conventional therapies to reduce pain, stiffness and swelling and to decrease the frequency of conventional therapy (I8-month study of 6 patients and 9-week study of 70 patients). Pilot studies have also shown anti-inflammatory activity in inflammatory gastrointestinal and respiratory diseases.

Animal and in vitro studies have shown that cat's claw has anti-inflammatory activity in acute and chronic inflammation, protecting against NSAID enteropathy and stress-induced ulcer formation. It has shown immunostimulant and anti-infectious properties both in animals and in vitro. In vitro studies have shown immunomodulator, and antimutagenic activity. Cat's claw has antineoplastic properties, and antioxidant activity. It is antiviral against RNA viruses in vitro. Cat's claw may have contraceptive properties. Recent in vitro evidence that cat's claw inhibits amyloid fibril formation and growth suggests that it may have therapeutic potential in the treatment of Alzheimer's disease and diabetes mellitus.

The leaves, stems, roots and bark of cat's claw are widely used by Central and South American peoples as an anti-inflammatory agent, immunomodulator and vulnerary. Common applications include the treatment of arthritis, rheumatism, asthma, cancer, fever, infectious diseases, abscesses, wounds, "bone pains," skin impurities, urinary tract infections and weakness. Cat's claw is used both for "normalization of the body" and disease prevention, as well as to treat hemorrhage and for postpartum recovery (excessive bleeding). Cat's claw is also used as a blood purifier, kidney cleanser, menstrual regulator and contraceptive.

Other reported uses include for dysentery, diarrhea, upset stomach and bowel inflammation and to eliminate gallstones. In the North American market, therapeutic claims and uses relate primarily to inflammatory and autoimmune disorders, HIV and cancer.

Constituents

The compounds named here have in vitro and in vivo pharmacological activity.
Alkaloids are thought to be the main active constituents. The oxindole alkaloid content varies significantly, depending on the plant part, the chemical race, the time of collection and the type of product. Two chemotypes have been reported, one with predominantly pentacyclic oxindole alkaloids and one with mainly tetracyclic oxindole alkaloids. For the pentacyclic chemotype, the average alkaloid content in root bark is 1 % to 2%, predominantly pteropodine (25% of the pentacyclic oxindole alkaloids), mitraphylline (25%) and speciophylline (20%). Root bark also contains small amounts of tetracyclic oxindole alkaloids (mainly rynchophylline and isorynchophylline) and indole alkaloids (akuammigine, dihydrocorynantheine, hirsuteine and hirsutine). Stem bark contains 0.5% pentacyclic oxindole alkaloids, predominantly isopteropodine (40%) and speciophylline (30%). Stem bark also contains small amounts of tetracyclic oxindole alkaloids (mainly rynchophylline and isorynchophylline) and indole alkaloids (hirsutine, hirsuteine and dihydrocorynantheine).
Other compounds found in cat's claw are quinovic acid glycosides, triterpenes, oleanolic acid and ursolic acid, proanthocyanidins B1, B2, B3, B4 and A, flavonoids, and tannins (about 20%).
Numerous other common constituents such as sterols have also been reported.

How much to take

Stem bark decoction: 28 g/L, heated at 85°C for 15 minutes; for disease prevention, 1 cup (250 ml) per week; for disease treatment, 1 L/day for a minimum of 3 months.
Root bark decoction: 20 g/L, heated at 85°C for 45 minutes and cooled for 10 minutes before filtering; decoction diluted 1:1 with hot water and given at the following daily dosages:
-13 years to adult: 60 ml decoction with 60 ml hot water
-10-12 years: 50 ml decoction with 50 ml hot water
-7-9 years: 30 ml decoction with 30 ml hot water
-3-6 years: 20 ml decoction with 20 ml hot water.
Root bark solid extract: 20 - 60 mg daily of 4:1 aqueous or acidic aqueous standardized extract.
Most supporting clinical evidence relates to the root bark (rather than the stem bark), which typically has higher alkaloid concentrations. Although many products claim standardized alkaloid content, a recent North American quality survey of retail products found a wide range in the total alkaloids and pentacyclic and tetracyclic oxindole alkaloids (some containing up to 80% tetracyclic oxindole alkaloids).

Side effects

No serious adverse effects have yet been reported. Cat's claw is contraindicated in autoimmune illness, multiple sclerosis, and tuberculosis. European practitioners avoid combining this herb with hormonal drugs, insulin, or vaccines. Cat's claw, until proven safe, should be taken only with great caution by pregnant or lactating women.

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