Cat's Claw - Medicinal Uses, Interactions, Side Effects, Dosage

Submitted by: peterthomas


Cat's Claw Cat's claw, also known as una de gato, belongs to the genus Uncaria and is indigenous to the Amazon rainforest and other tropical areas of South and Central America. Uncaria plants are woody vines with characteristic curved thorns, which resemble cat claws, on their stems. The species most widely used for medicinal purposes in Western countries is Uncaria tomentosa, but a related species, U. guianensis, is also employed. Other species are popular in Asia. Uses:Cat's claw preparations have been employed by native populations of the upper Amazon basin for generations to treat a myriad of health problems. The Peruvian Ashaninka Indians view the vine as "life giving." Cat's claw is traditionally used to treat arthritis and rheumatism, ulcers and other disorders of the gastrointestinal tract, asthma, wounds, gonorrhea, dysentery, and tumors; to help recover from childbirth; and as a contraceptive (in large doses). In North America and Europe, cat's claw is currently promoted for similar uses, with an emphasis on stimulating the immune system to treat disorders such as cancer, viral diseases (including AIDS), gastrointestinal illnesses, and inflammatory disorders. Anecdotal reports abound describing the healing properties of cat's claw preparations for many serious or chronic medical conditions. Pharmacology:Active chemical constituents from the roots, bark, and other parts of the plant include pentacyclic and tetra­cyclic oxindole alkaloids, quinovic acid glycosides, polyhydroxy­lated triterpenes, and several steroidal components (such as heta-sitosterol). Peruvian Indian healers can reportedly identify plants that have the most healing properties, which may be of a :;pecific botanic chemotype that contains more pentacyclic (rather Ihan tetracyclic) alkaloids. These constituents, as well as whole extracts, have been investigated in a variety of experiments to assess their proposed immunomodulatory, anti-inflammatory, and anticancer properties. Contrasting effects on the immune/inflammatory system are found in vitro. Aqueous bark extracts inhibit the inflammatory response by suppressing TNF-alpha production. 6 In contrast, higher concentrations induce IL-1 and IL-6 production, at least in rat alveolar macrophagesJ Although isolated pentacyclic oxindole al­kaloids enhance phagocytic activity and affect the proliferation of human lymphocytes, the tetracyclic alkaloids antagonize this ac­tivity on lymphocytes. In animal studies, extracts are reported to increase induced lymphocyte proliferation in splenocytes, in­crease peripheral white blood cell (WBC) counts, and enhance recovery of chemotherapy-induced leukopenia. Quinovic acid glycosides reduce an experimental inflammatory response, and oral administration attenuates indomethacin-induced intestinal in­flammation in animal models.Preliminary investigations of cat's claw extracts have dem­onstrated potential anticancer activity. Specific extracts appear to have cytoprotective antioxidant properties, and enhance repair of DNA breaks in irradiated rats. They inhibit specific leukemia and lymphoma cell lines by inducing apoptosis and cell death.Among miscellaneous in vitro studies, extracts have been found to inhibit stomatitis virus, to noncompetitively bind to estro­gen receptors, and to inhibit the cytochrome P450 3A4 iso­zyme.14-16 Tetracyclic oxindole alkaloids and other constituents from Uncaria species used in Asia are reported to have CNS (sedative, anticonvulsant) and cardiovascular (hypotensive, anti­thrombotic) properties in animal models. These effects have not been studied in South American species of Uncaria. Pharmacologic studies in humans are limited. In both a case report and a randomized, double-blind study of 24 subjects, smokers given U. tomentosa reportedly had decreased muta­genic activity of their urine. In another study, four healthy volun­teers took a 350-mg capsule of a purified water-soluble extract (called C-M ED-1 00) daily for 6 weeks. 9 An increase in WBCs was reported, but this was not clinically significant (mean increase from 6.6 to 7.18 x 10 3 ). Clinical Trials: No complete clinical trials have been pub­lished. One uncontrolled clinical trial has been partially described in a review article. 4 Thirteen subjects with HIV infection who re­fused other therapies were given 20 mg/day of a U. tomentosa root extract (containing 12 mg/g of pentacyclic oxindole alkaloids) for a period ranging from 2.2 to 5 months. The total leukocyte count and T4/T8 ratio were not altered. The relative and absolute lymphocyte count increased slightly (from 24% to 33.7%), which was statistically significant. In a double-blind, randomized, con­trolled trial that was unpublished but reported in company litera­ture, 40 patients with rheumatoid arthritis were given three 20-mg capsules daily of Krallendorn (by Immodal Pharmaka), a popular European cat's claw extract, or placebo for 6 months. 18 Two of three primary outcomes were reportedly improved in the treat­ment group, including objective evaluations of number and sever­ity of tender joints (p <>