Efficacy and safety of freeze-dried cat's claw in osteoarthritis of the knee: mechanisms of action of the species Uncaria guianensis.

2001-09
Inflammation research : official journal of the European Histamine Research Society ... [et al.] 50(9)
- J Piscoya
- Z Rodriguez
- S A Bustamante
- N N Okuhama
- M J Miller
- M Sandoval

PubMed: 11603848
DOI: 10.1007/pl00000268

Study Design

Type: Randomized Controlled Trial (RCT)
Population: 45 patients with osteoarthritis of the knee
Methods: 30 treated with freeze-dried Uncaria guianensis, 15 with placebo, 4-week trial
Duration: 4 weeks
Funding: Unclear

Aim

The purpose of this investigation was to evaluate the ability of cat's claw, an Amazonian medicinal plant, to treat osteoarthritis of the knee, collect safety and tolerance information and compare the antioxidant, and anti-inflammatory actions of Uncaria guianensis and Uncaria tomentosa in vitro.

Materials and methods

Forty-five patients with osteoarthritis of the knee were recruited, 30 were treated with freeze-dried U guianensis, and 15 with placebo. Hematological parameters were assessed on entry and exit of the four-week trial. Pain, medical and subject assessment scores and adverse effects were collected at weeks 1, 2 and 4. The antioxidant and anti-inflammatory activity of the cat's claw species was determined by the alpha,alpha-diphenyl-beta-picrylhydrazyl (DPPH) free radical scavenging method. Inhibition of TNFalpha and prostaglandin E2 (PGE2) production was determined in RAW 264.7 cells by ELISA.

Results

Cat's claw had no deleterious effects on blood or liver function or other significant side-effects compared to placebo. Pain associated with activity, medical and patient assessment scores were all significantly reduced, with benefits occurring within the first week of therapy. Knee pain at rest or at night, and knee circumference were not significantly reduced by cat's claw during this brief trial. In vitro tests indicated that U guianensis and U. tomentosa were equivalent at quenching DPPH radicals (EC50, 13.6-21.7 microg/ml) as well as inhibiting TNFalpha production. However, the latter action was registered at much lower concentrations (EC50, 10.2-10.9 ng/ml). Cat's claw (10 microg/ml) had no effect on basal PGE2 production, but reduced LPS-induced PGE2 release (P < 0.05), but at higher concentrations than that required for TNFalpha inhibition.

Conclusion

Cat's claw is an effective treatment for osteoarthritis. The species, U guianensis and U tomentosa are equiactive. They are effective antioxidants, but their anti-inflammatory properties may result from their ability to inhibit TNFalpha and to a lesser extent PGE2 production.

Research Insights

Cat's Claw→Reduced Knee Circumference
Knee pain at rest or at night, and knee circumference were not significantly reduced by cat's claw during this brief trial.
Effect
Neutral
Effect size
Small
Cat's Claw→Reduced Knee Pain at Rest
Knee pain at rest or at night, and knee circumference were not significantly reduced by cat's claw during this brief trial.
Effect
Neutral
Effect size
Small
Cat's Claw→Reduced Medical Assessment Score
Pain associated with activity, medical and patient assessment scores were all significantly reduced, with benefits occurring within the first week of therapy.
Effect
Beneficial
Effect size
Moderate
Cat's Claw→Reduced Patient Assessment Score
Pain associated with activity, medical and patient assessment scores were all significantly reduced, with benefits occurring within the first week of therapy.
Effect
Beneficial
Effect size
Moderate
Cat's Claw→Reduced Straining
Pain associated with activity, medical and patient assessment scores were all significantly reduced, with benefits occurring within the first week of therapy.
Effect
Beneficial
Effect size
Moderate

Adverse Events Reported

Cat's Claw→Overall tolerability
Cat's claw had no deleterious effects on blood or liver function or other significant side-effects compared to placebo.
Finding
No significant difference