Antioxidant activity of Piper nigrum L. essential oil extracted by supercritical CO2 extraction and hydro-distillation

The aim of this study was to optimize the antioxidant activity of Piper nigrum L. essential oil extracted using the supercritical carbon dioxide (SC-CO2) technique. Response surface methodology was applied using a three-factor central composite design to evaluate the effects of three independent extraction variables: pressure of 15-30 MPa, temperature of 40-50 degrees C and dynamic extraction time of 40-80 min. The DPPH radical scavenging method was used to evaluate the antioxidant activity of the extracts. The results showed that the best antioxidant activity was achieved at 30 MPa, 40 degrees C and 40 min. The extracts were analyzed by GC-FID and GC-MS. The main components extracted using SC-CO2 extraction in optimum conditions were beta-caryophyllene (25.38 +/- 0.62%), limonene (15.64 +/- 0.15%), sabinene (13.63 +/- 0.21%), 3-carene (9.34 +/- 0.04%), beta-pinene (7.27 +/- 0.05%), and a-pinene (4.25 +/- 0.06%). The essential oil obtained through this technique was compared with the essential oil obtained using hydro-distillation. For the essential oil obtained by hydro-distillation, the most abundant compounds were beta-caryophyllene (18.64 +/- 0.84%), limonene (14.95 +/- 0.13%), sabinene (13.19 +/- 0.17%), 3-carene (8.56 +/- 0.11%), beta-pinene (9.71 +/- 0.12%), and alpha-pinene (7.96 +/- 0.14%). Radical scavenging activity of the extracts obtained by SC-CO2 and hydro-distillation showed an EC50 of 103.28 and 316.27 mu g mL(-1) respectively. (C) 2014 Elsevier B.V. All rights reserved.