Cats Claw (Uncaria tomentosa)
Uncaria tomentosa, known as cats’ claw after its curved, claw-like thorns that grow on its stem, is a vine that can climb as high as 100 feet. It grows mostly in the Amazon rainforest up to 100 feet high, as well as other tropical areas in South and Central America. Much of the cat's claw sold in the United States was grown in Peru. Cat’s claw includes two species, Uncaria tomentosa and Uncaria guinaensis and the extract is usually made from their root bark most commonly from U. tomentosa.
The bark and root have been used by South Americans for centuries to treat health problems including arthritis, stomach ulcers, inflammation, dysentery, and fevers. It is marketed as an herbal remedy to treat viral infections, intestinal bacterial overgrowth, parasites, diverticulitis, peptic ulcers, colitis, gastritis, hemorrhoids, arthritis, and certain cancers.
Constituents of cat’s claw extracts include proanthocyanidins [proanthocyanidin B2 (the main component), proanthocyanidin B4, proanthocyanidin C1, an epicatechin trimer, epiafzelechin-4β→8-epicatechin, and an epicatechin tetramer, oxindole alkaloids (isopteropodine, pteropodine, rhynchophylline, mytraphylline, speciophylline, uncarine F and uncarine E), indole alkaloidal glucosides (cadambine, 3-dihydrocadambine and 3-isodihydrocadambine), quinovic acid glycosides, tannins, polyphenols, catechins, beta sitosterol, and proteins which individually or synergistically contribute to their therapeutic properties.
Preliminary clinical findings suggest that cat’s claw may benefit patients with active rheumatoid arthritis, and be useful for the treatment of denture stomatitis. Cat’s claw also was shown to exert anticancer effects against several cancer cell lines, and anti-neoplastic effects in a breast tumor model. It was also reported to stimulate healthy hematopoietic tissue cells and reduce side effects, such as neutropenia, associated with chemotherapy. These observations were reported in cancer patients as well. In a study of breast cancer patients, cat’s claw reduced adverse effects due to chemotherapy and improved the quality of life in patients with advanced cancer.
In vitro studies show that constituents of this plant enhance phagocytosis, display immunomodulatory properties, alleviate inflammation, and possess antiviral and antimutagenic activities. A cat’s claw extract was also shown to modulate DNA repair in human skin. The oxindole alkaloids have immunostimulating properties in vitro, increasing phagocytotic activity and synthesis of WBCs and enhancing T-helper cell function. Inhibition of TNF-alpha production has been linked to observed anti-inflammatory activities. Mitraphylline isolated from cat’s claw was also identified as possessing anti-inflammatory effects by inhibiting the release of interleukins 1α, 1β, 4, 17, and TNF-α.
In other studies, aqueous extracts of cat’s claw were shown to enhance DNA repair after chemical-induced damage. Protection against oxidative DNA damage following UVB exposure may occur via enhanced base excision repair and inherent antioxidant effects. The biphasic way cat’s claw modulates anxiety, initially inducing and then reversing the effect after long-term administration, is attributed to the presence of alkaloids and flavonols.
The quinovic acid glycoside purified fraction of cat’s claw was shown to inhibit the growth of human bladder cancer cell lines by inducing apoptosis through modulation of NF-κB. Cat’s claw also inhibited lactate dehydrogenase-A, an enzyme that is highly expressed in malignant and treatment-resistant tumors with poor clinical outcomes. In vivo studies demonstrated antineoplastic effects against breast tumors due to modulation of oxidative stress and synergy among constituents with antioxidant properties, rather than alkaloid activity.
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