Cat's claw inhibits TNFalpha production and scavenges free radicals: role in cytoprotection

Free Radic Biol Med. 2000 Jul 1;29(1):71-8. doi: 10.1016/s0891-5849(00)00327-0.


Cat's claw (Uncaria tomentosa) is a medicinal plant from the Amazon River basin that is widely used for inflammatory disorders and was previously described as an inhibitor of NF-kappaB. Cat's claw was prepared as a decoction (water extraction) of micropulverized bark with and without concentration by freeze-drying. Murine macrophages (RAW 264.7 cells) were used in cytotoxicity assays (trypan blue exclusion) in response to the free radical 1, 1-diphenyl-2-picrilhydrazyl (DPPH, 0.3 microM) and ultraviolet light (UV) light. TNFalpha production was induced by lipopolysaccharide (LPS 0.5 microg/ml). Cat's claw was an effective scavenger of DPPH; the EC(50) value for freeze-dried concentrates was significantly less than micropulverized (18 vs. 150 microg/ml, p <.05). Cat's claw (10 microg/ml freeze-dried) was fully protective against DPPH and UV irradiation-induced cytotoxicity. LPS increased TNFalpha media levels from 3 to 97 ng/ml. Cat's claw suppressed TNFalpha production by approximately 65-85% (p <.01) but at concentrations considerably lower than its antioxidant activity: freeze-dried EC(50) = 1.2 ng/ml, micropulverized EC(50) = 28 ng/ml. In conclusion, cat's claw is an effective antioxidant, but perhaps more importantly a remarkably potent inhibitor of TNFalpha production. The primary mechanism for cat's claw anti-inflammatory actions appears to be immunomodulation via suppression of TNFalpha synthesis.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Antioxidants / pharmacology*
  • Bepridil / analogs & derivatives
  • Bepridil / pharmacology
  • Biphenyl Compounds
  • Cat's Claw*
  • Cell Death / drug effects
  • Cell Line
  • Cell Survival / drug effects*
  • Cell Survival / radiation effects
  • Free Radical Scavengers*
  • Free Radicals
  • Lipopolysaccharides / pharmacology
  • Macrophages / cytology
  • Macrophages / drug effects
  • Macrophages / physiology*
  • Mice
  • Picrates*
  • Plant Extracts / pharmacology*
  • Plant Stems
  • Plants, Medicinal*
  • Tumor Necrosis Factor-alpha / biosynthesis*
  • Ultraviolet Rays


  • Antioxidants
  • Biphenyl Compounds
  • Free Radical Scavengers
  • Free Radicals
  • Lipopolysaccharides
  • Picrates
  • Plant Extracts
  • Tumor Necrosis Factor-alpha
  • Bepridil
  • 1,1-diphenyl-2-picrylhydrazyl