To enhance the extraction efficiency and reduce the energy consumption, an emerging technology named negative pressure cavitation extraction (NPCE) has been shown to be a feasible option for the extraction of bioactive compounds in agricultural crops and medicinal plants. Meanwhile, it can be applied at the pilot scale as a manufacturing process for edible and medicinal plants. Currently. NPCE was proposed for extraction of baicalin, wogonoside, baicalein and wogonin from Radix Scutellariae on the basis of a central composite design (CCD) and response surface methodology (RSM). With proper optimization (80 mesh of particle size, 40 mL/g of liquid/solid ratio, 75% aqueous ethanol as extraction solvent, 60 min extraction time and -0.07 MPa vacuum degree). NPCE was observed to have good extraction efficiency compared with other conventional extraction methods. Furthermore, the antioxidant activities of crude extracts with different extraction methods were assessed by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging assay. Our results showed that NPCE extract possessed better antioxidant activity with IC50 value of 3.24 mu g/mL compared with the UAE, HRE and SE extracts with IC50 values of 7.85, 12.14 and 11.44 mu g/mL, respectively. (C) 2011 Elsevier B.V. All rights reserved.