Response Surface Optimization of Extraction and Antioxidant Activity of Total Flavonoids from Seed Shell of Juglans mandshurica

The seed shell of Juglans mandshurica is a waste product from seed kernel processing in the food industry. For the first time, the optimal conditions of ultrasonic-assisted extraction for total flavonoids from seed shell of Juglans mandshurica (TFSSJM) were investigated and the antioxidant activity of TFSSJM was analyzed. Box-Behnken Design (BBD) combined with response surface methodology (RSM) was used. The optimal conditions were obtained as flows: ultrasonic power 250W, ultrasonic time 31.2 min and solid-liquid ratio1:31.4 (g/mL). The flavonoids yield was 6.62 mg/g under these optimal conditions. And TFSSJM had better capability of scavenging ABTS, DPPH and hydroxyl radical than BHT, there was dose effect relationship. IC50 of ABTS and hydroxyl radical-scavenging was 33 mu g/mL and 0.762 mg/mL respectively. The results indicated the ultrasonic-assisted method could be used as an effective and feasible method to extract total flavonoids from seed shell of Juglans mandshurica, and TFSSSM had excellent antioxidant activity, which can be used as a potential source of natural antioxidant.