Optimum SFE condition for lignans of Schisandra chinensis fruits

The fruits of Schisandra chinensis were extracted with supercritical carbon dioxide under various conditions of temperature (40-80 degrees C) and pressure (13.6-34.0 MPa) and each extract was analyzed by high-performance liquid chromatography for the main bioactive lignans schisandrol A (1), schisandrol B (2), schisandrin A (3), schisandrin B (4), and schisandrin C (5). When the extraction time was sufficient (30 min/100 mg plant material) the temperature and pressure of the supercritical carbon dioxide had no distinct effect on the extraction yields of the targetted lignans. If, however, the extraction time was 6 min, increasing the pressure greatly enhanced the yields of the lignans. The extraction efficiency of supercritical fluid extraction (SFE) was compared with that of conventional extraction with organic solvent. The efficiency of extraction of S. chinensis lignans by SFE was approximately 80 % that by methanol extraction but was superior to that achievable by use of other solvents such as chloroform-methanol (2:1), n-hexane, and petroleum ether. The results obtained suggest that in terms of efficiency and selectivity SFE could be used as an alternative to conventional extraction with organic solvent.