Extraction of Lepidium apetalum seed oil using supercritical carbon dioxide and anti-oxidant activity of the extracted oil

Abstract

The supercritical fluid extraction (SFE) of Lepidium apetalum seed oil and its anti-oxidant activity were studied. The SFE process was optimized using response surface methodology (RSM) with a central composite design (CCD). Independent variables, namely operating pressure, temperature, time and flow rate were evaluated. The maximum extraction of Lepidium apetalum seed oil by SFE-CO₂ (about 36.3%) was obtained when SFE-CO₂ extraction was carried out under the optimal conditions of 30.0 MPa of pressure, 70 °C of temperature, 120 min of extraction time and 25.95 L/h of flow rate. GC-MS analysis showed the presence of four fatty acids in Lepidium apetalum seed oil, with a high content (91.0%) of unsaturated fatty acid. The anti-oxidant activity of the oil was assessed by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging assay and 2,2'-azino- bis(3-ethylbenzthiazoline-6-sulphonic acid) diammonium salt (ABTS) test. Lepidium apetalum seed oil possessed a notable concentration-dependent antioxidant activity, with IC₅₀ values of 1.00 and 3.75 mg/mL, respectively.

Figure 1

Response surfaces representations for the yield of oil (a–f) from Lepidium apetalum seed. (a) Effect of pressure (P) and temperature (T) under fixed flow rate (F) 25L/h and extraction time (t) 90 min; (b) Effect of P and t at F = 25 L/h and T = 60 °C; (c) Effect of F and P at T = 60 °C and t = 90 min; (d) Effect of T and t at P = 25 MPa and F = 25 L/h; (e) Effect of F and T at P = 25 MPa and t = 90 min; (f) Effect of F and t at P = 25 MPa and T = 60 °C.

Figure 2

Total ion chromatogram (TIC) of the fatty acid methyl ester of Lepidium apetalum seed oil extracted by SFE-CO₂ (A) and conventional organic solvent extraction (B).

Figure 3

Antiradical activity determined using DPPH and ABTS. (a) The DPPH radical-scavenging of BHT. The concentration was from 3 µg/mL to 60 µg/mL; (b) The DPPH radical-scavenging of Lepidium apetalum seed oil. The concentration was from 0.5 mg/mL to 10 mg/mL. Data are averages with S.D. (error bars) from at least three independent experiments. * P < 0.05, versus control; (c) The ABTS radical-scavenging of BHT. The concentration was from 3 µg/mL to 60 µg/mL; (d) The ABTS radical-scavenging of Lepidium apetalum seed oil. The concentration was from 0.5 mg/mL to 10 mg/mL. Data are averages with S.D. (error bars) from at least three independent experiments. * P < 0.05, versus control.