Extraction of apigenin and luteolin from leaves of alfalfa (Medicago sativa L.) using mixtures of liquid carbon dioxide and ethanol

Abstract

The extraction of apigenin and luteolin from the alfalfa leaves; Medicago sativa (L.) using mixtures of liquid carbon dioxide (CO2) was performed at 5, 20 and 25°C. The extraction pressure was from 8.5 to 14 MPa. The extraction yields were compared with yields obtained by other solvent extraction methods, such as pure liquid CO2 extraction and conventional alcohol (methanol or ethanol) extraction. We conducted qualitative and quantitative analyses for luteolin and apigenin in the extract using HPLC and analyzed the extraction behavior. The effect of three operating parameters, temperature, pressure and composition of ethanol in the liquid CO2 solution, on the extraction yield was investigated using the single-factor method. The yields of luteolin and apigenin in the extraction were significantly improved by adjusting the operating temperature and amount of ethanol in the liquid CO2 solution, whereas a change in the selectivity of the extract was not observed.