Cat's-claw (una de gato) comes from the stem and root of two Amazonian woody vines belonging to the madder family. Both species are used interchangeably in South America. Commercial supplies are wild-harvested in Peru and Brazil.
The Piura Indians used a bark decoction of U. guianensis to treat inflammation, rheumatism, gastric ulcers and tumors, and as a contraceptive. Indian groups in Colombia and Guyana use it for dysentery. U. tomentosa is a South American folk medicine for intestinal ailments, gastric ulcers, arthritis, wounds, and cancer. Popular use in North America started in the 1990s.
Reports of successful use as a South American folk remedy for cancer prompted scientists in Germany, Austria, and Italy to take a closer look at cat's-claw. Compounds called proanthocyanidins were found to inhibit tumor growth in animals in the 1970s. Studies at the University of Munich in 1985 found several alkaloids in U. tomentosa root with significant immunostimulant activity. In 1993 Italian researchers found new compounds, quinovic glycosides, which showed antiviral, antimutagenic, and antioxidant effects in preliminary pharmacological tests. An Austrian research group found several alkaloids, including uncarine F, inhibit the growth of tumor cells in laboratory tests. Root material may be as much as four times stronger than stem bark.
In Germany and Austria, standardized cat's-claw extracts have been given to cancer patients under a physician's care to stimulate their immune system. They have also been used in cases of rheumatoid arthritis, allergies, herpes infections, gastric ulcers, gastritis, and AIDS. The products are registered pharmaceuticals in these countries and are available only by prescription. Controlled clinical studies are underway, but results to date are inconclusive.
The dried cut-and-sifted root and stem, powdered root and stem, capsules, tinctures, tablets, and extracts standardized for total alkaloid content are now available in the American market.
Like other immunostimulants, cat's-claw should be avoided in diseases of the immune system itself, such as tuberculosis, multiple sclerosis, and HIV infection. [It is not known to be safe for children or pregnant or nursing women.] In Germany and Austria, standardized products are not allowed to be combined with therapies involving hormones, insulin, fresh blood plasma, vaccines, or in certain other specialsituations. Consult a physician before using cat's-claw.