Cat’s claw is a medicinal herb traditionally used to stimulate the immune system. Research has shown it may boost immune function, reduce inflammation, and even help with chemotherapy. Read on to discover the potential health benefits and adverse effects associated with this herb.

What Is Cat’s Claw?

Cat’s claw (Uncaria tomentosa) is a medicinal plant that grows in the Amazonian rainforest and other tropical areas in Central and South America. The use of the herb dates back to the Inca civilization. Indigenous cultures of South America used cat’s claw for inflammation, cancer, viral infections, ulcers, and to stimulate the immune system [1, 2].

It gets its name from its thorns, which resemble the claws of cats.

Cat’s claw can refer to Uncaria tomentosa and Uncaria guianensis. Most commercial preparations such as teas, tablets, and capsules contain U. tomentosa [3, 4, 2].

The two different types of cat’s claw contain different active compounds and have different medicinal properties. Uncaria tomentosa contains more pentacyclic oxindole alkaloids (POAs), while U. guianensis is richer in tetracyclic oxindole alkaloids (TOAs) [3, 4].

TOAs act on the central nervous system (brain and spinal cord), whereas POAs affect the immune system [5].

TOAs cancel out the effects of POAs. Therefore it is important when purchasing and consuming cat’s claw extracts to be sure that they have been tested for TOA and POA levels [5].

Differences between the two types are conveyed in the chemical structure. Pentacyclic alkaloids are found in the vine bark while tetracyclic alkaloids are found in the leaves and stem of the plant [6, 7].

Main Beneficial Compounds of Cat’s Claw

Cat’s claw is rich in three major groups of chemical compounds: alkaloids, terpenoids, and flavonoids [4].

Specific compounds found in cat’s claw include:

• Mitraphylline: an alkaloid usually found in older leaves. It has potential anticancer effects, causing cell death in sarcoma and breast cancer cells [4, 8].
• Rhynchophylline: an alkaloid isolated from the bark. It may help with convulsions, lightheadedness, numbness, and hypertension [9, 10].
• Isopteropodine: an alkaloid isolated from the leaves. It has antimicrobial properties against (Gram-positive) bacteria [9, 11].
• Uncarine (C, D, and E): a family of alkaloids