RELEVANCE OF UNCARIA TOMENTOSA ("CAT'S CLAW")
FOR CANCER PREVENTION AND TREATMENT

(From the April 15, 1995 Bulletin of the National Institute of Traditional Medicine, Peru's Ministry of Health, English translation by Laura León)

Cancer is generally caused by external agents and develops in three stages. In the first stage, a carcinogenic agent that can be physical (e.g, ultraviolet light), chemical (e.g, compounds inhaled by smokers) or viral (e.g, IIIV) causes a mutation; that is, an alteration in cellular genetic material. This process occurs in a matter of hours or days. In the second stage, that may last years or even decades, the affected cells start growing either spontaneously or influenced by promoting agents. In the third stage, the malignant tumor is clinically present.

Prevention

The mutagenic effect of carcinogens may be reduced by the action of some micronutrients (Wattemberg, 1983), mainly of plant origin (Hayatsu et al., 1988). The epidemiologic evidence indicates that carotenoids and antioxidant vitamins from certain vegetables and fruits play an important role in cancer prevention (e.g., Block, 1993). A rubiacea named "cat's claw" (Uncaria tomentosa (Willd) DC.) can now be added to the known sources of natural antimutagenic agents. The native ashaninkas of the peruvian rainforest obtain an aqueous extract from its bark and use it to treat cancer, arthritis, and other illnesses (Cabieses, 1994; Jones, 1994; Steimberg, 1994).

In laboratory experiments with application of ultraviolet rays and chromatographic analyses on several Salmonella typhimurium strains, researchers from the universities of Milano, Napoli, and Pavia in Italy (Rizzi et al; 1993) showed that the quinovic acid glycosides contained in U. tomentosa have an antimutagenic action. In the same study, a test in vivo measured the mutagenesis induced by the urine of two subjects, a smoker and a non-smoker. Both subjects drank during 15 days a daily dose of 6.5 g of cat's claw extract obtained following the ashaninka method. The non-smoker's urine did not show abnormal levels of mutagenic activity before the treatment. Neither did it show changes during of after treatment. The smoker's urine exhibited an important mutagenic action that was substantially reduced with the treatment and continued at normal levels even 8 days later. Figure 1 Shows one of the results. According to Rizzi et al. (1993), the antimutagenic action of U. tomentosa may be due to an antioxidant mechanism, i.e; one that inhibits oxidative free radicals that are at the core of carcinogic processes.

The findings of Aquino et al. (1989) concerning U. tomentosa glycosides inhibitory action on an RNA virus (vesicular stomatitis virus) are also relevant here.

Treatment

Cancer patients that experienced relief using cat's claw have offered numerous public testimonies, and high retes of tumoral remission have been claimed by Peruvian phytotherapists on the basis of extended casuistry (e. g; Mírez, 1989). Yet, these studies lack rigour. The existing scientific evidence is detailed below.

U. tomentosa raises the cancer patient's inmunoglobuline count (Keplinger, 1982) and its extracts exhibit cytostatic activity in some human hemopoletic tumors (Huber, 1985). Peluso et al. (1993) showed an inhibitory effect on abnormal cellular proliferacion due to direct action on DNA polimerases.

Stuppner et al. (1993) studied the effect of six oxindolic alcaloids contained in U.tomentosa on the proliferation of leukemic cells IIL 60 and U-937. Five alcaloids inhibited their growth significantly. Their action was selective, for they did not inhibit progenitor cells from bone marrow. Figure 2 Shows the most marked effect (uncarine F) and that of the sixth alcaloid (mitraphylline). The antitumoral action of the active alcaloids may be explained by their demostrated activation of macrophagues (Wagner et al., 1985; Keplinger et al; 1989).

The non-alcaloid components of U. tomentosa include poliphenolic compounds. Montenegro et al. (1976) identified epicatequine and four procianidines of known anticoplastic action.

Thus, though scientific evidences are still scanty, they support the use of U. tomentosa in cancer prevention and treatment since they reveal benefits at diverse phases of the illness.

At present, the greatest need is the clinical follow-up of phytotherapy patients, and the research would do well in distinguishing between antincoplastic and antinflammatory actions. U. tomentosa is a confirmed antiinflammatory drug (Aquino et al; 1991) and many symploms associated with malignant tumors are due to inflammatory processes surrounding the tumor.

The side effects of U. tomentosa should be more thoroughly investigated. No side-effects have been reported until now from clinical studies, but rigorous evaluations of cat claw's effects on hepatic and renal variables, as well as on conception and fetal health, are lacking.

On a more theoretical level, we need to determine whether the combined anticarcinogenic effects of the glycosides, alcaloids and procianidines containeed in the ashaninka extract are additive or whether the extract has an effect that is superior to the sum of its parts.

Finally, comparing the effects of U. tomentosa experimentally and clinically to those of Uncaria guianensis, a more abundant cat's claw, would be valuable. U. guianensis shares several, though not all of the alcaloids (Alvarez et al; 1988) and glycosides (Yepes et al; 1991) of U. tomentosa.

On the practical side, standardization and eventual improvement of the extract obtention is needed. Concerning its preservation, one may assume that freeze-drying the extract is the best option (Cabieses, 1994).

References

Alvarez, C.M; Sánchez, O; Stilke, R; & Lock de Ugaz, O. (1988). Algunos constituyentes de Uncaria guianensis. Revista de Química (Catholic University of Peru) 11,99-104.

Aquino, R; De Fco, V; De Simone, F; Pizza, C; & Cirino, G. (1991). Plant metabolites, new compounds, and antiinflamatory activity of Uncaria Tomentosa. Journal of Natural Products 54, 453-459.

Aquino, R; De Simone, F; & Pizza, C. (1989). Plant metabolites, structure, and in vitro antiviral activity of quinovic acid glycosides from Uncaria tomentosa and Guettarda platypoda. Journal of Natural Products 52,679-685.

Block, G. (1993). Micronutrients and cancer; Time for action? Journal of the National Cancer Institute, 85,846-848.

Cabieses, F. (1994) La uña de gato y su entorno. Lima : Vía Láctea.

Hayatsu, H; Arimoto, S; & Negishi, T. (1988) Dietary inhibitors of mutagenesis and carcinogenesis. Mutation Research 202,429-446.

Huber, C. (1985). La influencia de los extractos de Uncaria en algunas funciones linfocíticas, en la fagocitosis de granulocitos y en el crecimiento in vitro de tumores hemopoiéticos humanos. Innsbruck: University Clinic. (Spanish translation.)

Jones, Kenneth. (1994) Uña de Gato: Life-giving vine of Peru. The American Herb Association Quarterly Newsletter, Vol. X, Issue 3, p. 4.

Keplinger, K. (1982) Cytostatic, contraceptive, and antiinflamatory agents from Uncaria tomentosa. PTC Int. Appl. WO 82 01 130, Austria.

Keplinger, K; Wagner, H; & Kreutzkamp, B. (1989). Oxindole alkaloids having properties stimulating the immunologic system. Washington, D.C.: United States Palent # 4844901.

Mírez Melgarejo, Felipe. (1989) Fitoterapia en el cáncer avanzado. Simposium "Phytotherapy in Medicine." Lima : INVESCIENCIAS, Peruvian Institute of Social Security.

Montenegro de Matta, S.F; Delle Monache, F; Ferrari, F; & Marini-Bertollo, G.B. (1976) Alkaloids and procianidins of an Uncaria sp. from Peru. II Farmaco 31, 527 - 535.

Peluso, G; La Cara, F; & De Feo, V. (1993). Antiproliferativo su cellule tumorale di estrattie metaboliti da Uncaria tomentosa. Studi in vitro sulla loro azione su DNA polimerasi. Lima: Second Italo-Peruvian Congress of Andean Ethnomedicine, October 27-30.

Rizzi, R; Re,F; Bianchi, A; De Feo, V; de Simone, F; Bianchi, L; & Stivala , L.A. (1993) Mutagenic and antimutagenic activities of Uncaria tomentosa and its extracts. Journal of Ethnopharmacology 38, 63 - 77.

Steimberg, P.N. (1994) Uncaria tomentosa ("cat's claw"). Wonder herb from the Amazon. New Editions Health World, 40-45.

Stuppner, II; Sturm, S; Geisen, G; Zillian, U; & Konwalinka, G. (1993) A differential sensitivity of oxindole alkaloids to normal and leukemic cell lines. Planta Medica 59, A, 583.

Wagner, II; Kreutzcamp, B; & Jurcic, K. (1985). Die Alkaloide von Uncaria tomentosa undihre Phagozytose-steigernde Wirkung. Planta Medica, 419 - 432.

Wattenberg, L. W. (1983) Inhibition of neoplasia by minor dietary constituents. Cancer Research Suppl. 43, 2448 - 2453.

Yépez, A. M; Lock de Ugaz, O; Alvarez, C.M; De Feo, V; Aquino, R; De Simone, F; & Pizza, C. (1991). Quinovic acid glycosides from Uncaria guianensis. Phytochemistry 30, 1635 - 1637.