Uncaria tomentosa (Willd.) DC, or Una de Gato, known as ‘Cat’s claw’, belonging to the family Rubiaceae, is a medicinal plant native to the Peruvian Amazon. Uncaria has been described as a woody climber. It is a vine or shrub with characteristic penduncles that appear as curved hooks on the side shoots. The plant can grow to a length of up to 30 m (100 ft), climbing by means of these thorns. The leaves are elliptic with a smooth edge, and grow in opposing pairs. The species is widely distributed in tropical regions, including Southeast Asia, Africa, and South America.
The species in which the largest number of compounds has been identified is the Peruvian U. tomentosa, or ‘cat’s claw’, around 50 different compounds have been isolated from this plant. Interestingly, 15 of these compounds were also reported as novel. This structurally diverse species includes alkaloids such as rhynchophylline, isorhynchophylline and their corresponding N-oxides, mitraphylline and isomitraphylline, the uncarines, and rotundifoline, and ursane type pentacyclic triterpenes including a variety of ursolic acid derivatives.