Cat's claw (Uncaria tomentosa), or una de gato, is a perennial, woody vine that is native to Peru. Currently, it also grows throughout Central and South America in countries such as Columbia, Panama, and Ecuador. Its name is due to the claw-like thorns along the vine, which help the plant adhere itself up to a hundred feet into the limbs and trunks of trees. The vine seasonally produces yellowish-white flowers. Most often the inner bark is harvested because it is believed to contain the most health promoting properties.
The active substances in cat's claw are oxindole alkaloids, quinovic acid glycosides, proanthocyanidins, tannins, and several other phytochemicals. Research has shown that there are two variant alkaloid chemical types of Uncaria tomentosa which differ both in their content and subsequent activity in the body. One chemical type contains pentacyclic oxindole alkaloids, pteropodine, isopteropodine, etc., which have a positive effect on the immune system. The other contains tetracyclic oxindole alkaloids, rhynchophylline and isorhynchophylline, which tend to counter the beneficial effects of the aforementioned pentacyclic alkaloids.
Cat's claw can be taken in 1 to 2 ml tinctures up to 2 times a day, as a capsule 350 to 500 mg once or twice per day, and as tea, 1 g per cup, 1 to 3 times per day. The appropriate levels of intake for optimizing the potential benefits of cat's claw is not yet known. In both human and animal studies no toxicity has been detected. Experts recommend that women who are pregnant avoid taking cat's claw.