Optimization of extraction process and activity study of peony seed oil by ultrasonic-assisted soxhlet extraction

Based on single-factor experiments, multiple regression fitting analysis was conducted using Design-Expert 11.0 software to explore optimal process of peony seed oil extracted by ultrasound-assisted Soxhlet extraction．Preliminary studies were conducted on antioxidant and antibacterial effects of peony seed oil．Results indicated that optimal extraction process for peony seed oil was as follows: extraction time of 55 minutes, ultrasonic power of 85 W, solid-liquid ratioby （g/mL）of 1∶13, and three extraction cycles．Under this optimal process, yield was verified at 32.02%．In vitro studies showed that at concentrations of 20, 40, 60, 80, and 100 mg/mL, free radical scavenging rate of peony seed oil increased with time．At 180 minutes, corresponding scavenging rates were 38.08%, 57.94%, 63.56%, 70.07%, and 74.70%, respectively．Meanwhile, peony seed oil exhibited different antibacterial effect on different bacterial strains．At a concentration of 0.5 mg/mL, peony seed oil had certain antibacterial effect on Escherichia coli, Staphylococcus aureus, and Enterococcus faecalis（39.4% to 50.1%）, while showing weaker antibacterial effect on Bacillus subtilis（19.1%）, but almost no antibacterial effect on Pseudomonas aeruginosa．Extraction process design for peony seed oil is reasonable, to provide reference for further optimization of peony seed oil process and its antioxidant and antibacterial effects．