How It Works
Bottom Line: There is no proof that cat's claw can treat cancer, HIV, or other serious medical conditions.
Cat's claw is a bark extract. In laboratory experiments, compounds found in cat's claw have been shown to stimulate the activity of specific immune cells (phagocytes and T-helper cells). Cat's claw extracts may lower blood pressure by relaxing the cells that line blood vessels and inhibiting the excitatory effect that the sympathetic nervous system (the "fight or flight" response) has on the heart and blood vessels. These extracts are also able to 1) slow some of the processes that cause inflammation and 2) enhance the repair of DNA in the laboratory setting. However, it is not known if these effects occur in the human body.
Purported Uses
As a method of birth control
No scientific evidence supports this use.
To treat cancer
No scientific evidence supports this use.
To treat gastrointestinal disorders
Laboratory studies suggest that cat's claw may be able to reduce inflammation, but there is no proof from clinical trials that cat's claw can treat gastrointestinal problems in humans.
To treat HIV and AIDS
Laboratory studies suggest that cat's claw can stimulate the activity of specific immune cells, but there is no proof from clinical trials that cat's claw can treat HIV or AIDS.
To reduce inflammation
Laboratory studies suggest that cat's claw may be able to reduce inflammation, but there is no proof from clinical trials that cat's claw can reduce inflammation.
Research Evidence
No clinical trials have tested the safety or effectiveness of cat's claw in humans.
Warnings
- Cat's claw is suspected to inhibit the liver enzyme cytochrome P450 3A4. This enzyme is necessary for metabolizing several drugs and eliminating them from the body. Therefore cat's claw might slow this important activity and raise the blood levels of drugs such as protease inhibitors, nonnucleoside reverse-transcriptase inhibitors, cyclosporine, some benzodiazepines, and many others. Patients should ask their doctor if cat's claw might interfere with the metabolism of any medication they are taking.
- This product is regulated by the F.D.A. as a dietary supplement. Unlike approved drugs, supplements are not required to be manufactured under specific standardized conditions. This product may not contain the labeled amount or may be contaminated. In addition, it may not have been tested for safety or effectiveness.
Do Not Take If
- You have an autoimmune disorder such as systemic lupus erythematosus (SLE)
- You are taking medication to lower your blood pressure (Cat's claw might lower blood pressure even lower).
- Are taking warfarin or other blood thinners (Cat's claw may increase the risk of bruising and bleeding).
Side Effects
- Diarrhea
- Low blood pressure
- One patient with systemic lupus erythematosus (SLE) experienced acute kidney failure after using cat's claw.
Scientific Name
Uncaria tomentosa
Common Name
Una de gato, life-giving vine of Peru, hawk's claw
Clinical Summary
Derived from the bark of the tree. In vitro studies show that its pentacyclic oxindole alkaloids enhance phagocytosis, display immunomodulatory properties specifically against NF
kB and TNFa, and alleviate inflammation
(9) (10) (11) (12). However, no human studies have been conducted to evaluate efficacy. Reported adverse reactions include hypotension and diarrhea. An additive effect with anticoagulants or hypotensives is possible; therefore caution should be exercised
(8). Cat's claw should be avoided in patients with autoimmune disorders (e.g. systemic lupus erythematosus).
Purported uses
- Birth control
- Cancer treatment
- GI disorders
- HIV and AIDS
- Inflammation
Constituents
- Oxindole alkaloids: Isopteropodine, pteropodine, rhynchophylline, mytraphylline, speciphylline
- Indole alkaloidal glucosides: Cadambine, 3-dihydrocadambine, and 3-isodihydrocadambine
- Hirsutine
- Quinovic acid glycosides
- Tannins
- Polyphenols
- Catechins
- Beta sitosterol
(1) (2)
Mechanism of Action
The oxindole alkaloids are claimed to have immunostimulating properties in vitro to increase phagocytotic activity and synthesis of WBCs
(9) and enhance T-helper cell function
(11). The major alkaloid rhynchophylline is claimed to be anti-hypertensive, relax the endothelial cells of blood vessels, dilate peripheral blood vessels, inhibit sympathetic nervous system activities, lower the heart rate and lower blood cholesterol. The alkaloid mytraphylline has diuretic properties, and hirsutine inhibits urinary bladder contractions and possesses local anesthetic
(3) (5) (9). The anti-inflammatory activity may be caused by the inhibition of TNF-alpha production
(10) (12). Uncaria tomentosa water extracts have been shown to enhance DNA repair after chemotherapy-induced damage
(14).
Adverse Reactions
Common: May cause diarrhea and lower blood pressure.
Case report: Acute renal failure in a patient with systemic lupus erythematosus (SLE)
(7)
Herb-Drug Interactions
Antihypertensives: Cat's claw may have an additive or synergistic hypotensive effect.
Anticoagulants / Antiplatelets: Cat's claw may have an additive anticoagulant effect.
CYP3A4: In vitro, cat's claw inhibits CYP3A4, indicating that it may theoretically increase the serum levels of drugs such as protease inhibitors, nonnucleoside reverse-transcriptase inhibitors, cyclosporine, some benzodiazepines, and others.
(8)
Literature Summary and Critique
Animal and in vitro data exist in cancer, immunostimulant, inflammation, and antiviral studies. Human studies are lacking, and further research is needed.
References
- Wirth C, et al. Pharmacologically active procyanidines from the bark of Uncaria tomentose. Phytomedicine 1997;4:265-6.
- Hemingway SR, Phillipson JD. Proceedings: alkaloids from south American species of Uncaria (Rubiaceae). J Pharm Pharmacol 1974;26(suppl):113.
- Rizzi R, et al. Mutagenic and antimutagenic activities of Uncaria tomentosa and its extracts. J Ethnopharmacol 1993;38:63-77.
- Paulsen SM. Use of herbal products and dietary supplements by oncology patients--Informed decisions? Highlights Oncol Pract 1998;15:94-106.
- Aquino R, et al. Plant metabolites: New compounds and anti-inflammatory activity of Uncaria tomentosa. J Nat Prod 1991;54:453-9.
- Keplinger K, et al. Uncaria tomentosa: ethnomedicinal use and new pharmacological, toxicological and botanical results. J Ethnopharmacol 1999; 64:23-34.
- Hilepo JN, et al. Acute renal failure caused by 'cat's claw' herbal remedy in a patient with systemic lupus erythematosus. Nephron 1997;77:361.
- Scott GN, Elmer GW. Update on natural product-drug interactions. Am J Health-Syst Pharm 2002;59:339-47.
- Sheng Y, Bryngelsson C, Pero R. Enhanced DNA repair, immune function and reduced toxicity of C-MED-100, a novel aqueous extract from Uncaria tomentosa. J Ethnopharmacol 2000;69:115-26.
- Sandoval M, et al. Cat's claw inhibits TNFalpha production and scavenges free radicals: role in cytoprotection. Free Radic Biol Med 2000;29:71-8.
- Riva L, et al. The antiproliferative effects of Uncaria tomentosa extracts and fractions on the growth of breast cancer cell line. Anticancer Res 2001;21:2457-61.
- Sandoval M, et al. Anti-inflammatory and antioxidant activities of cat's claw (Uncaria tomentosa and Uncaria guianensis) are independent of their alkaloid content. Phytomedicine 2002;9:325-37.
- Mur E, et al. Randomized double blind trial of an extract for the pentacyclic alkaloid-chemotype of Uncaria tomentosa for the treatment of rheumatoid arthritis. J Rheumatol 2002;29:678-81.
- Sheng Y, et al. DNA repair of aqueous extracts of Uncaria tomentosa in a human volunteer study. Phytomedicine 2001;8:275-82.
- Budzinski JW, et al. An in vitro evaluation of human cytochrome P450 3A4 inhibition by selected commercial herbal extracts and tinctures. Phytomedicine 2000;7:273-82.
