Supercritical CO2 extraction of bioactive compounds from local Peganum Harmala plant seeds and optimization of the extraction yield and the antioxidant activities

Abstract

A great variety of natural plants provide an important source of bioactive compounds having interesting applications in sensitive fields like food, pharmaceutical and cosmetic industries, particularly with the development of the supercritical carbon dioxide extraction. Therefore the present study focused on the study of this technique to extract valuable bioactive substances from seeds of a local natural plant known as Peganum harmala. The properties of the extracts were also considered, particularly insisting on the antioxidant activity potential. The extraction yield was optimized and the corresponding operating conditions were determined. A Box-Behnken statistical design was used to investigate the effect of operating parameters like pressure, temperature and particle size at a fixed supercritical CO2 flow rate of 50 g min−1 for an extraction time of 180 min. Furthermore, the total antioxidant activity of the plant extracts was assessed using the 2, 2-diphényl-1-picrylhydrazyl (DPPH) method whereas the Response surface methodology (RSM) combined with Box-Behnken design was used for the optimization of process key parameters. The highest extraction yield was achieved at a pressure of 300 bar, a temperature of 55 °C and a particle size of 0.3 mm. A maximum total phenolic content (TPC) and a 50% inhibition concentration (IC50) of 79.04 mg GAE/g E and 172.199 μg/mL, respectively were obtained at 100 bar and 35 °C for a particle size of 0.9 mm, whereas a total flavonoid content of 7.10 mg QE/g E was obtained still at 35 °C and for a particle size of 0.9 mm but at a pressure of 170.7 bar. Finally supercritical CO2 extraction showed to be an efficient technology, creating an added value through bioactive compounds with targeted properties like the antioxidant activity.