Solubility of boldo leaf antioxidant components (Boldine) in high-pressure carbon dioxide

This work contributes to the development of an enrichment process for antioxidant compounds in aqueous alcoholic extracts of boldo (Peumus boldus M.) leaves by using high-pressure CO2 as the solvent. Specifically we measured the high-pressure solubility (y2, molar fraction) of a selected bioactive compound in boldo leaves (boldine) in CO2 as a function of system temperature (298 K ≤ T ≤ 333 K) and pressure (8 MPa ≤ P ≤ 40 MPa). Experimental data was correlated by using a density-based model which is valid for solvent densities >607 kg/m3. Predicted solubility values are low (4 × 10−7 ≤ y2 ≤ 6 × 10−5) but comparable with those of nitrogen-containing organic compounds with similar molecular weight (327.4 Da) and solubility parameter (28.3 MPa0.5 at 313 K) as boldine.