Immune System Support* 5000 mg Equivalency 15:1 Standardized Extract Vegetarian Formula NOW® Cat"s Claw "5000" is a natural extract of the highest quality inner bark of authentic Uncaria tomentosa, an exciting herbal discovery from the Peruvian Rainforest. Also called Una de Gato, it has been used for hundreds of years by the native Ashanica Indians. Cat"s Claw "5000" is a concentrated water and alcohol extract standardized to contain a minimum of 3% Total Alkaloids (calculated as Mitraphylline) and 15% Total Polyphenols.