Development/optimization of a green procedure with ultrasound-assisted improved supercritical carbon dioxide to produce extracts enriched in oleanolic acid and ursolic acid from Scutellaria barbata D. Don

In the present study, the evaluation of oleanolic acid (OA) and ursolic acid (UA) from Scutellaria barbata D. Don was carried out using either an ultrasound-assisted supercritical carbon dioxide (UA-SC-CO2) extraction process or a heat reflux extraction (HRE) process. The influence of different variables was investigated to evaluate their influence on the yield. A reverse-phase HPLC system coupled with a UV detector was also used to quantify the levels of OA and UA in the extracts obtained using these two techniques. The optimum conditions for UA-SC-CO2 extraction from S. barbata D. Don were as follows: mean particle size of 0.355 mm, pressure of 27.6 MPa, temperature of 55 degrees C, CO2 flow rate of 2.1 mL/min (SIP) and 14.1% (v/v) aqueous ethanol (ethanol/water = 80/20, v/v) as modifier (co-solvent) for a 50 min extraction time. With these conditions, the yield of OA was 14.142 +/- 0.583 mu g/g of dry plant and the yield of UA was 59.275 +/- 2.414 mu g/g of dry plant. This result was comparable to that obtained from HRE in 80-90% ethanol at 75 degrees C for 180 min (3 extraction cycles). The experimental results show that UA-SC-CO2 extraction saves time and energy and uses much less organic solvent. Therefore, we can conclude that UA-SC-CO2 extraction is technically feasible for the extraction of OA and UA from S. barbata D. Don. (C) 2013 Elsevier B.V. All rights reserved.