Precipitation of sub-micron particles of 3,5-diprenyl-4-hydroxycinnamic acid in Brazilian propolis from supercritical carbon dioxide anti-solvent solutions

Abstract This study elucidates supercritical carbon dioxide (SC-CO 2 ) anti-solvent precipitation of 3, 5-diprenyl-4-hydroxycinnamic acid (DHCA) from the ethyl acetate solution of ultra-green Brazilian propolis. The SC-CO 2 anti-solvent process at 20 MPa and 328 K generated the precipitates containing DHCA (306 mg/g) more than that of the Soxhlet ethyl acetate extract (204 mg/g). A two factorial central composite response surface methodology was adopted to examine the effects of CO 2 flow rate and CO 2 expansion volume on mean particle size of the precipitate. Analysis of the DHCA recovered indicated that both factors are significant. The mean particle size fell as the CO 2 flow rate or the CO 2 volume increased. Finally, the dose-dependent concentrations from 25 to 400 μg/mL demonstrated that aqueous samples of the precipitated SC-CO 2 particulates effectively inhibited the growth of human colon (colo-205) cancer cells.