Effect of P. jiringa fruit rinds extracts on clonogenicity of HUVEC cells. (A) Effect of EtOH extract and EW extract. (B) The clonogenicity of the cells in 6-well plates after treatment with the extracts and controls. The clonogenic cell survival of HUVEC cells treated with: (−) 1% DMSO as negative control, (+) betulinic acid 20 μg/ml as positive control and indicated concentrations of the extracts (μg/ml). Values are means of two experiments, error bars equal ± SD. Plating efficiency was 13.7 ± 1.00%. *P < 0.05, **P < 0.01 and ***P < 0.001, comparing to control.