Experimental endometriosis reduction in rats treated with Uncaria tomentosa (cat's claw) extract

Eur J Obstet Gynecol Reprod Biol. 2011 Feb;154(2):205-8. doi: 10.1016/j.ejogrb.2010.10.002. Epub 2010 Oct 27.


Objective: The aim of this study was to analyze the macroscopic and histological changes that occur in experimental endometriosis after treatment with Uncaria tomentosa.

Study design: Experimental endometriosis was induced in twenty-five female Wistar rats. After three weeks, 24 animals developed grade III experimental endometriosis and were divided into two groups. Group "U" received U. tomentosa extract orally (32 mg/day), and group "C" (control group) received a 0.9% sodium chloride solution orally (1 ml/100g of body weight/day). Both groups were treated with gavage for 14 days. At the surgical intervention and after the animal was euthanized, the implant volume was calculated with the following formula: [4π (length/2)×(width/2)×(height/2)/3]. The autotransplants were removed, dyed with hematoxylin-eosin, and analyzed by light microscopy. The Mann-Whitney test was used for the independent samples, and the Wilcoxon test analyzed the related samples, with a significance level of 5%.

Results: The difference between the initial average volumes of the autotransplants was not significant between the groups (p = 0.18). However, the final average volumes were significantly different between the groups (p = 0.001). There was a significant increase (p = 0.01) between the initial and final average volumes in the control group, and treatment with the U. tomentosa caused a marked reduction in the growth over time (p = 0.009). Histologically, in the experimental group (n = 10) six rats had a well-preserved epithelial layer, three had mildly preserved epithelium, and one had poorly preserved epithelium. The epithelial layer occasionally presented sporadic epithelial cells. The control group (n = 12) presented seven cases (58.3%) of well-preserved epithelial cells and five cases (41.7%) of mildly preserved epithelial cells.

Conclusions: Cat's claw extract appears to be a promising alternative for treating endometriosis.

MeSH terms

  • Animals
  • Cat's Claw / chemistry*
  • Disease Models, Animal
  • Endometriosis / drug therapy*
  • Endometriosis / pathology
  • Female
  • Phytotherapy
  • Plant Extracts / therapeutic use*
  • Rats
  • Rats, Wistar


  • Plant Extracts