Kinetics, composition and biological activity of Eupatorium intermedium flower extracts obtained from scCO2 and compressed propane

• High extract yields were obtained with propane as solvent.
• Similar chemical profiles were found between propane and CO2 extract.
• E. intermedium flower extracts with antibacterial activity were obtained using scCO2.

The extraction of Eupatorium intermedium flowers was evaluated using supercritical CO2 (scCO2) and compressed propane. Experiments were carried out under the following conditions using scCO2 as the solvent: 15.0, 20.0 and 25.0 MPa and at 303.15, 328.15 and 353.15 K, and the maximum extraction yield was 5.85 wt%. With propane as the solvent the conditions applied were 3.0, 6.5 and 10.0 MPa and 293.15, 313.15 and 333.15 K, and the maximum extraction yield was 9.34 wt%. When scCO2 was used the pressure had a positive effect on the extraction yield while with the use of propane both variables (pressure and temperature) had a positive effect. Gas chromatographic analysis showed that the major compounds were spathulenol, caryophyllene oxide, caryophyllene (E), germacrene D, bicyclogermacrene and carotol, for the two solvents. The highest values for antioxidant activity were found for the extracts obtained using scCO2 at 303.15 K and 15 MPa and propane at 333.15 K and 3.0 MPa, determined by the DPPH method and the phosphomolybdenum reduction method. The extract obtained using propane at 293.15 K and 3.0 MPa presented the highest phenolic content. The highest antibacterial activity was observed for the extracts obtained with scCO2 against Staphylococcus aureus and Listeria monocytogenes.

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