Uncaria tomentosa (Willdenow ex Roemer & Schultes) De Candolle is a large woody vine indigenous to a number of central and South American countries. This species, also known as una de gato or cat's claw, is widely used in folk healing as an immunomodulatory, anti-cancer and anti-inflammatory remedy. The list of treated diseases include for instance gastric ulcers, diarrhea, gonorrhea, arthritis and rheumatism, acne, diseases of the urinary tract and cancers. The most often way of cat's claw medical administration is drinking its decoctions prepared through boiling in water or by macerating in alcohol the inner bark or the root bark.

Sometimes it is used in combination with other ingredients such as chuchuhuasi bark, capsaicin, burdock root, sheep sorrel or slippery elm bark. In vitro and in vivo studies indicate oxindole alkaloids (speciophylline, mitraphylline, uncarine F, pteropodine, isomitraphylline, uncarine E) as main compounds responsible for such medicinal properties, however, many other constituents must be also taken into consideration due to broad pharmacological activity of this plant.

Numerous investigations have been carried out to isolate and determine secondary metabolites of cat's claw. There are over fifty different compounds including, besides above-mentioned alkaloi

ds and their N-oxides, ursane type pentacyclic triterpenes with a variety of ursolic acid derivatives, quinovic acid glycosides, sterols and procyanidins. Although it seems that activity of Uncaria tomentosa is likely to result from a combination of these and other compounds which work synergistically, some of them are reported to possess very strong pharmacological properties. Quinovic acid glycosides (q.a. 3ß-O-(ß-D-quinovopyranosyl)-(27-1)-ß- D-glucopyranosyl ester and (28)-ß-D-glucopyranosyl ß-D-glucopyranosyl ester, were found as anti-inflammatory and anti-viral agents. Ursolic acid was proved to posses very strong anti-proliferative and proapoptotic properties. Beta-sitosterol, campesterol and stigmasterol was shown to have anti-inflammatory and antiarteriosclerotic properties, whereas strong antioxidant potency was assigned to proanthocyandins which are the main phenolic phytochemicals identified in cat's claw.

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