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.
