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 °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 °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 β-caryophyllene (25.38±0.62%), limonene (15.64±0.15%), sabinene (13.63±0.21%), 3-carene (9.34±0.04%), β-pinene (7.27±0.05%), and α-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 β-caryophyllene (18.64±0.84%), limonene (14.95±0.13%), sabinene (13.19±0.17%), 3-carene (8.56±0.11%), β-pinene (9.71±0.12%), and α-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 µg mL−1 respectively.