Uncaria tomentosa, and Una de Gato.
Cat's claw is a tropical vine clinging to 100-foot (and taller) trees by using its namesake "claws."
Cat's claw (una de gato in Spanish) refers to at least 20 plants with sharp curved thorns, both native to the South and Central American tropical rain forests, with most of the commercial production focused on Uncaria tomentosa. Ethically harvested cat's claw bark is a major source of income for many Brazilian and Peruvian villages.
Pentacyclic oxindole alkaloids (pteropodine, isopteropodine, isomitraphylline, uncarine F), tetracyclic oxindole alkaloids (rhynchophylline, isorhynchophylline), quinovic acid glycosides, procyanidins, triterpenoid saponins.
Usually used as a tincture. The tannins in the herb are released only if it is taken in an acidic medium; add a little lemon juice to a quarter-cup of water to which you add the tincture or prepare as a tea. For convenience it may be taken as a capsule.
The traditional application of cat's claw has been to treat rheumatoid arthritis. Compounds with cat's claw are thought to block the body's production of inflammation producing substances and slightly reduce pain, but not the swelling that goes with typical arthritis. The herb is also used for stomach ulcers, gastritis, eczema, "break-bone fever," and liver diseases. Recent clinical studies find that the herb is useful for relieving knee pain. Since the 1980's, cat's claw most common use in modern herbal medicine is an immune stimulant. The oxindole alkaloids in cat's claw strengthen the immune system and also improve circulation by lowering blood pressure. The master rain forest herbalist Leslie Taylor has used cat's claw tinctures and teas to treat cancer and HIV with remarkable success. The Ashanica Indians of Peru believe that cat's claw has life giving properties, and their folklore states that if you drink one cup of bark decoction a week it will ward off diseases, help ease bone pain, and cleanse the body. There is certainly a bit of validity to these claims. At least one researcher referred to cat's claw as the "opener of the way" for its ability to cleanse the entire intestinal tract.
Women should avoid use of this herb when trying to get pregnant.