Removal of toxic aristolochic acid components from Aristolochia plants by supercritical fluid extraction

This study aimed to assess the feasibility of using supercritical fluid extraction (SFE) to remove the major aristolochic acid components from two Aristolochia herbs, Fructus Aristolochiae and Caulis Aristolochiae manshuriensis. Four operating parameters, viz., vessel pressure (P), vessel temperature (T), mole fraction (X) of entrainer (absolute ethanol) in supercritical carbon dioxide and extraction mode (EM) were investigated for their impact on the AA extraction. Statistical analysis revealed that the extraction mode and the mole fraction of entrainer were the only two dominant factors governing the AA extraction. For a 1-g powdered sample of 100-120 mesh size which had been pretreated with 2 mL absolute ethanol for 12 h, the removal of AA-I and AA-II from the two Aristolochia plants was best carried out in dynamic mode using a vessel pressure of 194 bar, vessel temperature of 50 °C, entrainer concentration of 0.2 mole fraction, and extraction time of 4 h. The removal rates of AA-I and AA-II were respectively 65.2% and 59.1% from Fructus Aristolochiae, and 81.3% and 81.2% from Caulis Aristolochiae manshuriensis.