Optimization of extraction conditions of bioactive compounds from Hypericum perforatum L. petals by response surface methodology

In the present study, the use of the ultrasonic apparatus has been investigated in the extraction process of Hypericum perforatum L. flowers. The effect of methanol to water ratio (24.77, 35, 50, 65, and 75.22 percent), time (1.59, 5, 10, 15, and 18.40 minutes), and temperature (24.77, 35, 50, 65, and 75.22 °C) on the extraction of phenolic compounds, flavonoids and antioxidant activity of the extract using two methods of 2,2-diphenyl-1-picrylhydrazyl (DPPH%) and (FRAP) Ferric Reducing antioxidant power (FRAP) were studied using the response surface method and central composite design. The results of RSM showed that the highest extraction efficiency was obtained at 50% methanol/water ratio, 70 °C, and 15 min. Under optimal conditions, the corresponding values for total phenol content, total flavonoid content, and antioxidant assays of %DPPH and FRAP were 28.46 (mg gallic acid equivalent (GAE) g-1 dry weight (DW)), 19.75 (mg quercetin g−1 DW), 89.23 (%DPPH), and 3.57 FRAP µmol Fe++ /g DW respectively. In addition, results express the effectiveness of the proposed conditions and reliability of central composite design analysis on the extraction of phenolic antioxidants from H. perforatum flowers. Using ultrasonic is a low-cost, simple, and efficient method for the extraction of phenolic antioxidants, which increases the extraction efficiency and thermal protection of phenolic antioxidants.