Optimization of ultrasonic-assisted extraction of phenolic compounds and antioxidant activities From Pistacia atlantica Desf. galls using response surface methodology

In the present study, the response surface methodology (RSM) using Box-Behnken design (BBD) was employed to optimize conditions for the extraction of phenolic compounds from Pistacia atlantica Desf. leaf galls. Three variables were evaluated at three levels (15 experimental runs): the extraction time (40 min, 45 min, and 50 min), the solid-to-liquid ratio (1:10 g/ml, 1: 20 g/ml, and 1:30 g/ml) and temperature (40 degrees C, 50 degrees C, and 60 degrees C). According to the three-dimensional response surface, the optimum extraction phenolic compounds were found at 40 min extraction time, 1:20 g/ml solid-liquid ratio, and 60 degrees C extraction temperature. In these conditions, the content of TPC, TFC, CTC, and antioxidant activity (DPPH and iron chelation) were 139.88 mg GAE/g DW, 2.43 mg QE/g DW, 121.32 mg CE/g DW, 65.94 mg AAE/g DW, and 501.38 mg TE/g DW, respectively. The results indicate an agreement between the prediction values and experimental ones, which points the success of the optimization. Moreover, they indicate that P. atlantica galls produce a high amount of antioxidants and anti -radicals under optimized conditions determined by RSM. Actually, the used method is a simple, reliable one that serves as an alternative to various other extraction techniques.