The antiproliferative effects of Uncaria tomentosa extracts and fractions on the growth of breast cancer cell line

Uncaria tomentosa, also known as "Una de gato", is a Rubiaceae species wide ly used in South-American folk medicine for the treatment of cancer, arthri tis, gastritis and epidemic diseases. Extracts of the plant have been shown to possess cytostatic and anti-inflammatory activity as well as mutagenic and antimutagenic properties. However, to date no studies have been carried out to verify the direct antitumor activity of the extracts. The present s tudy investigates the effects of some extracts and their chromatographic fr actions from the bark of U. tomentosa on the growth of a human breast cance r cell line (MCF7). Our data indicated that, in addition to the antimutagen ic activity, U. tomentosa extracts and fractions exert a direct antiprolife rative activity on MCF7. The bioassay-directed fractionation from barks and leaves resulted in the isolation of two active fractions, which displayed an IC50 of 10 mg/ml and 20 mg/ml, respectively and an antiproliferative eff ect, with about 90% of inhibition at a concentration of 100 mg/ml.