Extraction of the Main Ingredients from Chuanxiong by CO2 Supercritical Fluid Extraction

As one of the most frequently used medicinal herbs in China, Chuanxiong Rhizoma (Chuanxiong) is notable for its beneficial effects in alleviation of cardio- and cerebro- vascular disorders. Results from previous phytochemical, pharmacological and pharmacokinetic studies supported the contributions of 10 main components, namely ferulic acid (3), senkyunolide I (4), senkyunolide H (5), senkyunolide A (6), coniferylferulate (7), Z-ligustilide (8), sedanolide (9), 3-butylidenephthalide (10), riligustilide (11) and levistolide A (12), for therapeutic outcomes of the herb. To prepare a Chuanxiong extract, which is selectively enriched with these main components, the supercritical fluid extraction (SCFE) technique using CO2 was chosen in the present study due to its superiority in extraction of lipophilic components, especially thermo-labile components from natural products. Eight Chuanxiong samples were extracted under different SCFE conditions. Contents of 3 - 12 in SCFE extracts and remained in herbal residues were determined using HPLC-UV and compared with those in 95% ethanol extracts of the respective herbal samples. The results showed that contents of 3 - 12 were generally enriched by SCFE with higher recoveries achieved for lipophilic constituents, including the three most abundant constituents 6, 7 and 8. Moreover, extraction yield of the less lipophilic 3, 4 and 5 was improved by adding ethanol as entrainer. Higher flow rate of CO2 (10 - 13 L/h vs 9 - 12 L/h) enhanced the overall extraction, while lower temperature (32℃ vs 40℃) reduced degradation of thermo-labile compounds, in particular 7, 8 and 10. Our established SCFE condition yielded high extraction recoveries for both total (75.6%) and three major chemical ingredients (6: 83.5%, 7: 77%, 8: 78.3%) from Chuanxiong with an adequate overall reproducibility, demonstrating a successful application of SCFE in selective enrichment of certain ingredients and efficient extraction of thermo-labile components from medicinal herbs using specifically designed SCFE conditions.