Uncaria tomentosa

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Uncaria tomentosa
Uncaria tomentosa.png
Scientific classification edit
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Asterids
Order: Gentianales
Family: Rubiaceae
Genus: Uncaria
Species:
U. tomentosa
Binomial name
Uncaria tomentosa

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.[1][2] The plant root bark is used in herbalism for a variety of ailments, and is sold as a dietary supplement.[2][3][4]

Description[edit]

Uncaria tomentosa is a liana deriving its name from hook-like thorns that resemble the claws of a cat.[2][4] U. tomentosa can grow to a length of up to 30 m (100 ft), climbing by means of these thorns.[1] 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.[1]

Taxonomy[edit]

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.[4] The two are frequently confused but U. tomentosa is the more commonly used in traditional medicine.[5][6] U. tomentosa is further divided into two chemotypes that remain under preliminary research for their properties and compounds.[7] 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.[4][6]

Phytochemicals[edit]

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.[3][6][8] It also contains rhynchophylline.

Traditional medicine[edit]

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.[2][4][6] The part used medicinally is the bark of the vine or root.[2] As of 2015, there is no high-quality clinical evidence that it has any benefit in treating diseases.[3][6]

Alzheimer's Disease and Cognitive Decline[edit]

A study published in Nature in 2019 found that specific phytochemicals in Cat's claw (proanthocyanidins) had an inhibitory effect on the formaiton of both beta-amyloid plaques and tau protein "tangles".[9] The accumulation of beta-amyloid plaques and tau protein tangles have been posited as a primary cause of Alzheimer's Disease.[10] This finding led the authors to conclude: "The discovery of a natural plant extract from the Amazon rain forest plant (i.e. Uncaria tomentosa or cat's claw) as both a potent “plaque and tangle” inhibitor and disaggregator is postulated to represent a potential breakthrough for the natural treatment of both normal brain aging and Alzheimer's disease."

Other studies have found a significant improvement in cognitive function following the administration of Cat's claw extract, albeit exclusively in rats. A 2021 study published in Chinese Medicine found that rats with Streptozotocin-induced Alzheimer's Disease showed improved memory function after being given a large, highly concentrated dose of Cat's claw extract.[11] Again, the authors concluded that their findings "amply implicate that both of UTE and URE are worthy of being developed clinically into pharmaceutical treatment for AD."

Critics have suggested such enthusiasm is unwarranted as the plaque and tangle inhibition (and the cognitive improvements) observed in such studies took place either in vitro or in rodents. The effects were also obtained using very high concenrations of Cat's claw extract that would not be practical in a clinical setting with human subjects. As of 2022, no Alzheimer's patients have had their disease significantly reversed or its progression halted by the administration of Cat's claw, either in its whole or purified extract form. While more research is needed, claims that Cat's claw extract represents a likely cure for Alzheimer's Disease are, at best, grossly exaggerated.

Adverse reactions[edit]

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.[4][6] Reactions can include itching, rash and allergic inflammation of the kidneys. People requiring anticoagulant therapy should not use cat's claw.[2][failed verification][6][failed verification] 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.[8]

See also[edit]

References[edit]

  1. ^ a b c d "Uncaria tomentosa". Germplasm Resources Information Network (GRIN). Agricultural Research Service (ARS), United States Department of Agriculture (USDA). Retrieved 2008-03-01.
  2. ^ a b c d e f "Cat's claw". Drugs.com. 7 June 2018. Retrieved 11 January 2019.
  3. ^ a b c "Assessment report on Uncaria tomentosa (Willd. ex Schult.) DC., cortex" (PDF). European Medicines Agency. 10 March 2015. Retrieved 11 January 2019.
  4. ^ a b c d e f "Cat's claw: Uncaria tomentosa (Willd.) DC.; Uncaria guianensis (Aubl.) Gmel". American Botanical Council. 30 January 2018. Retrieved 11 January 2019.
  5. ^ 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.
  6. ^ a b c d e f g "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.
  7. ^ 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.
  8. ^ a b "Cat's Claw". 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.
  9. ^ Snow AD, Castillo GM, Nguyen BP, Choi PY, Cummings JA, Cam J, Hu Q, Lake T, Pan W, Kastin AJ, Kirschner DA, Wood SG, Rockenstein E, Masliah E, Lorimer S, Tanzi RE, Larsen L. (February 2019). "The Amazon rain forest plant Uncaria tomentosa (cat's claw) and its specific proanthocyanidin constituents are potent inhibitors and reducers of both brain plaques and tangles" (PDF). Scientific Reports. 9 (1): 561. Bibcode:2019NatSR...9..561S. doi:10.1038/s41598-019-38645-0. PMC 6365538. PMID 30728442.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  10. ^ Murphy MP, LeVine H 3rd. (2010). "Alzheimer's disease and the amyloid-beta peptide". J Alzheimers Dis. 19 (1): 311–323. doi:10.3233/JAD-2010-1221. PMC 2813509. PMID 20061647.
  11. ^ Xu, Qing-Qing; Shaw, Pang Chui; Hu, Zhen; Yang, Wen; Ip, Siu-Po; Xian, Yan-Fang; Lin, Zhi-Xiu (2021-10-27). "Comparison of the chemical constituents and anti-Alzheimer's disease effects of Uncaria rhynchophylla and Uncaria tomentosa". Chinese Medicine. 16 (1): 110. doi:10.1186/s13020-021-00514-2. ISSN 1749-8546. PMC 8555092. PMID 34706756.

External links[edit]