This study elucidates the supercritical carbon dioxide (SC-CO2.) anti-solvent micronization of Brazilian propolis particulates that contain the bioactive compound, 3,5-diprenyl-4-hydroxycinnamic acid (DHCA). The effects of the concentration of propolis solution and flow rate of CO2 on purity, recovery and mean particle size of DHCA-rich particulates are studied using a two-factor central composite response surface methodology. Experimental results indicate that the purity of DHCA increases as the CO2 flow rate decreases. The mean particle size increases as the feed concentration exceeds 27 mg/mL The growth of human colon (Colo 205) and breast (MDA-MB-231) cancer cells that were treated with these SC-CO2 precipitates was inhibited at concentrations from 25 to 250 mu g/mL This work demonstrates that the SC-CO2 anti-solvent micronization of the propolis solution, activated by these DHCA-rich precipitates, is a feasible means of inhibiting the growth of human colon and breast cancer cells. (C) 2009 Elsevier B.V. All rights reserved.