Investigation of essential oil extraction and antioxidant activity of Echinophora platyloba DC. using supercritical carbon dioxide

Essential oils of Echinophora platyloba DC. were extracted with application of supercritical carbon dioxide (SC-CO2 ) and hydro-distillation (HD) extraction methods. The effects of SC-CO2 experimental variables such as pressure (80-240 bar), temperature (308-328 K), particle size (0.30-0.90 mm), and dynamic extraction time (30-150min) on the extraction yield and antioxidant activity of the prepared essential oils were investigated using a central composite design (CCD). The experimental data were fitted well to a second-order polynomial equation using regression analysis. The maximum yield obtained at the optimal conditions (1.1850 +/- 0.0550%) was more than that achieved by hydro-distillation method (1.120 +/- 0.0440%). The chemical compositions of the SC-CO2 and HD extracts were identified by GC-MS analysis and determined by GC-FID analytical method. The main components of the essential oil extracted by SC-CO2 method were found to be Linalool (16.02%), Trans-beta-Ocimene (11.58%), alpha-Pinene (7.10%), Anisole, 2,4,6-trimethyl (6.98%) and Spathulenol (5.29%). Moreover, the components of the essential oil extracted by HD method were Trans-beta-Ocimene (46.99%), Spathulenol (9.04%), beta-Myrcene (6.24%), rz-Limonene (5.38%) and alpha-Pinene (4.55%). The antioxidant and free radical scavenging activities of the obtained essential oils were determined by 2,2-diphenyl-l-picrylhydrazyl (DPPH). Radical scavenging activity of the essential oils extracted by SC-CO2 and hydro-distillation methods exhibited an IC50 of 122.62 mu g/ml and 413.35 mu g/ml, respectively. To the best of researchers' knowledge, the present study provides the first report addressing the essential oil extraction of Echinophora platyloba DC. using supercritical carbon dioxide technique. (C) 2016 Elsevier B.V. All rights reserved.