From The Cancer Chronicles #30
© Dec. 1995 by Ralph W. Moss, Ph.D.

Uña de gato, or Cat's claw, is the popular name for an herb scientifically called Uncaria tomentosa Willd. This is a woody vine, technically a member of the Rubiaceae family. It grows in the high Amazonian basin region of Peru at elevations of 700 to 2500 meters, in the valleys of the Perene and the Paucartambo rivers. Typically, the vine grows to two to three inches or more in diameter. A related plant, Uncaria guianensis, which grows at lower elevations, is also called Cat's claw in Peru and employed for the same purposes.

The bark of this vine is widely used as a medicine in Amazonian regions. Either the bark itself is powdered or else it is made into a concentrated extract. (The liquid that drains from the stem when it is cut is also used locally as a medicine.) Since time immemorial it has been used a traditional medicine among the Ashaninka Indians. Its applications are many: arthritis, rheumatism, gastritis, and ulcers are commonly treated by cat's claw.

In 1974, cat's claw was "discovered" or rather rediscovered by the Austrian scientist, Klaus Keplinger of Innsbruck University. It was British scientists who first correctly identified the plant as Uncaria tomentosa. It was soon found that injections of some of the active compounds derived from this thick bark increased T-4 lymphocyte count, thereby reinforcing the immune system, and having anti-inflammatory properties.

Cat's claw is also said to neutralize stomach ulcers, to work as a diuretic and to regenerate cells. Dr. Keplinger's first experiments were done in veterinary problems: a rare kind of "crown" virus that affects cats as well as the "Maed visna" virus that afflicts lambs. Keplinger then went on to treat herpes infections in humans.In 1986, he started to work with HIV-infected people.

According to some Peruvian accounts, after 20 days, people with AIDS showed beneficial effects on their immune systems and in 30 days their lymphatic glands showed improvement.

Subsequent research in Germany and Austria has shown that a water (aqueous) extract of the bark has an enhancing effect on the process by which white blood cells engulf and digest microbes, phagocytosis. It is said to have remarkable effects in the treatment of neurobronchitis and allergies as well as any disease related to the immune system.


Dr. Keplinger has found that the bark contains various oxindole alkaloids, as well as alloisopteropodine (the so-called isomer A), which he is working on to develop into an anti-AIDS drug. Italian scientists have also discovered quinovic acid glycosides in the bark, which also possesses antiviral activity. Scientists at Naples University, for instance, have shown the presence of anti-inflammatory beta-sitosterols, which would lend credence to the traditional claims of anti-inflammatory properties.

Italian scientists have also shown how non-toxic the herb really is. Given to mice orally at a high dose of 5 grams per kilogram of body weight (or into the peritoneal cavity at 2 g/kg body weight), as well as similar doses of the raw alkaloid, they produced no observable changes in behavior over 14 days of observation.

The herb-derived compounds did have a significant antioxidant and antimutagenic effect (which is usually a sign of anti-cancer activity, as well.) Nevertheless, the herb is not recommended for women intending to become pregnant, because of its mild contraceptive effect.

According to news reports coming out of Peru, Dr. Keplinger has had great success in fighting AIDS with this medicinal herb. "The new product has been administered for the last six years to patients with AIDS....the clinical symptoms disappeared" (El Comercio, 11/28/88 and 7/17/93). According to the same article, early investigations done in Austria suggest that cat's claw may be useful when used in conjunction with conventional chemotherapy and radiation, in order to minimize the side effects of such treatments, such as nausea.

There is a natural tendency on the part of some to deny such unsubstantiated reports and to see the whole topic of cat's claw as yet another health fad. I think that would be a tragic mistake. Needless to say, all such reports need to be taken with a grain of salt, and should be subjected to controlled studies for confirmation.

However, before NCI runs off and starts testing "unnatural" derivatives [as its director, Dr. Klausner, suggests], it should carry out a patient, respectful and sympathetic study of the South American and European experience with the herb. Sit at the feet of the healers and shamans, as well as the most advanced scientists who have spent decades researching this topic. In that way, we all might learn how cat's claw can be added to the growing international medicine bag of herbal treatments useful against cancer.

Ralph W. Moss, Ph.D. is director of the The Moss Reports for cancer patients. Dr. Moss is the author of eleven books and three documentaries on cancer-related topics. He is or has been an advisor on alternative cancer treatments to the National Institutes of Health, the National Cancer Institute, the American Urological Association, Columbia University, the University of Texas, the Susan G. Komen Foundation and the German Society of Oncology. He wrote the first article on alternative medicine for the Encyclopedia Britannica yearbook. He is listed in Marquis Who's Who in America, Who's Who in the World, Who's Who in the East, and Who's Who in Entertainment (as a film documentarian). This Web site does not advocate any particular treatment for cancer. We urge you to always seek competent medical advice for all health problems, especially cancer. Before consulting our site please read our full Disclaimer statement.

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