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

This study elucidates supercritical carbon dioxide (SC-CO2) anti-solvent precipitation of 3, 5-diprenyl-4-hydroxycinnamic acid (DHCA) from the ethyl acetate solution of ultra-green Brazilian propolis. The SC-CO2 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 CO2 flow rate and CO2 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 CO2 flow rate or the CO2 volume increased. Finally, the dose-dependent concentrations from 25 to 400 μg/mL demonstrated that aqueous samples of the precipitated SC-CO2 particulates effectively inhibited the growth of human colon (colo-205) cancer cells.