Cat's Claw or Una de Gato (Uncaria tomentosa) is an herb that grows wild in the highlands of the Peruvian Amazon. The native Ashanica Indians have used the inner bark of cat's claw for possibly thousands of years.* Recent research in Europe and China has identified the alkaloid compounds in cat's claw that possess antioxidant properties. Allergy Research Group's cat's claw is derived from only the inner bark.