Optimization of Ultrasonic Assisted Aqueous Two-phase Extraction of Total Flavonoid from Loquat Flower and Its Antioxidant Activity

Ultrasonic assisted aqueous two-phase extraction of total flavonoid from loquat flower and its antioxidant activity were studied. With the yield of total flavonoid as the index, the extraction conditions were optimized by single factor test and response surface design, and the antioxidant effect was evaluated by measuring the damage of H₂O₂, the scavenging rate of ·OH and total reducing power.The results showed that the optimum extraction condition were determined as follows: The time of ultrasonic was 45 min, the mass content of loquat flower, (NH₄)₂SO₄ and PEG400 was 0.2%, 18% and 28%. By adopting the process, the extraction yield of total flavonoid from loquat flower was 26.96%.The damage of H₂O₂ to total flavonoid was not obvious, the half scavenging concentration (IC₅₀) values of ·OH was 0.297 mg/mL.The scavenging effect was superior to vitamin C (V_C). The results suggest that total flavonoid from loquat flower is potential natural antioxidant.