Abstract:

The ultrasonic-assisted extraction of flavonoids from Ipomoea batatas Lam leaves (FIBL) was explored by
orthogonal array design. The antioxidant and bacteriostatic activities of FIBL in vitro were investigated. The results showed
that the optimal extraction conditions of FIBL were ethanol concentration of 75%, liquid-solid of 30:1 (mL/g), ultrasonic
treatment time of 40 min, reflux extraction time of 50 min, extraction temperature of 70 ℃, and repeated extraction time
of 2. Under the optimal extraction conditions, the yield of FIBL was up to 6.03%. As characterized by UV-vis and IR
spectroscopy, FIBL possessed common spectral characteristics of flavonoids. Furthermore, FIBL had scavenging capacity
against superoxide anion and DPPH radicals, but weaker than vitamin C. FIBL also revealed excellent inhibitory effect on
Staphylococcus aureus, Escherichia coli and Bacillus subtilis.

Key words: Ipomoea batatas Lam leaves, flavonoids, extraction, antioxidant activity, bacteriostatic action