Uncaria tomentosa is a woody vine found in the tropical jungles of South and Central America. It is known as cat's claw or uña de gato in Spanish because of its claw-shaped thorns. The plant root bark is used in herbalism for a variety of ailments, and is sold as a dietary supplement.
Uncaria tomentosa is a liana deriving its name from hook-like thorns that resemble the claws of a cat. U. tomentosa can grow to a length of up to 30 m (100 ft), climbing by means of these thorns. The leaves are elliptic with a smooth edge, and grow in opposing pairs. Cat's claw is indigenous to the Amazon rainforest, with its habitat being restricted primarily to the tropical areas of South and Central America.
There are two species of cat's claw commonly used in North America and Europe, Uncaria tomentosa and Uncaria guianensis, having different properties and uses. The two are frequently confused but U. tomentosa is the more commonly used in traditional medicine. U. tomentosa is further divided into two chemotypes that remain under preliminary research for their properties and compounds. There are other plants which are known as cat's claw (or uña de gato) in Mexico and Latin America; however, they are entirely different plant species, belonging to neither the genus Uncaria, nor to the family Rubiaceae.
Phytochemicals in Uncaria tomentosa root bark include oxindole and indole alkaloids, glycosides, organic acids, proanthocyanidins, sterols, and triterpenes, glycosides, tannins, polyphenols, catechins, and beta-sitosterol.
Cat's claw has been used as a traditional medicine in South American countries over centuries for its supposed health benefits, and is a common herbal supplement. The part used medicinally is the bark of the vine or root. As of 2020, there is no high-quality clinical evidence that it has any benefit in treating diseases.
Individuals allergic to plants in the family Rubiaceae and different species of Uncaria may be more likely to have adverse reactions to cat's claw. Reactions can include itching, rash and allergic inflammation of the kidneys. People requiring anticoagulant therapy should not use cat's claw. Phytochemicals in cat’s claw may inhibit the liver enzyme, CYP3A4, which oxidizes organic compounds, and may interfere with the intended effect of prescription drugs.
- "Uncaria tomentosa". Germplasm Resources Information Network (GRIN). Agricultural Research Service (ARS), United States Department of Agriculture (USDA). Retrieved 2008-03-01.
- "Cat's claw". Drugs.com. 7 June 2018. Retrieved 11 January 2019.
- "Assessment report on Uncaria tomentosa (Willd. ex Schult.) DC., cortex" (PDF). European Medicines Agency. 10 March 2015. Retrieved 11 January 2019.
- "Cat's claw: Uncaria tomentosa (Willd.) DC.; Uncaria guianensis (Aubl.) Gmel". American Botanical Council. 30 January 2018. Retrieved 11 January 2019.
- Gattuso M, di Sapio O, Gattuso S, Pereyra LE (2004). "Morphoanatomical Studies of Uncaria tomentosa and Uncaria guianensis Bark and Leaves". Phytomedicine. 11 (2–3): 213–223. doi:10.1078/0944-7113-00315. PMID 15070175.
- "Detailed Scientific Review of Cat's Claw (archived)". M.D. Anderson Center. 31 May 2006. Archived from the original on 26 August 2013. Retrieved 10 January 2019.
- Keplinger K, Laus G, Wurm M, Dierich MP, Teppner H (1999). "Uncaria tomentosa (Willd.) DC. — Ethnomedicinal Use and New Pharmacological, Toxicological and Botanical Results" (PDF). Journal of Ethnopharmacology. 64 (1): 23–34. doi:10.1016/S0378-8741(98)00096-8. PMID 10075119.
- "Cat's claw: Clinical and research information on drug-induced liver injury". LiverTox, US National Institute of Diabetes and Digestive and Kidney Diseases. 18 February 2019.
- Media related to Uncaria tomentosa at Wikimedia Commons
- Uncaria tomentosa List of Chemicals (Dr. Duke's Databases)