Optimization of ultrasound-assisted extraction of Moringa leaf flavonoids and evaluation of their bioactivities

This study optimized the ultrasound-assisted extraction (UAE) of total flavonoids from Moringa oleifera leaves using response surface methodology. The effects of ethanol concentration, solid–liquid ratio, ultrasonic time, and ultrasonic temperature on extraction efficiency were investigated through single-factor and Box-Behnken design experiments. The optimal extraction conditions were determined as 50% ethanol, 1:70 solid–liquid ratio, 61 °C extraction temperature, and 45 min ultrasound time, yielding 5.40% total flavonoids. The flavonoids demonstrated strong in vitro antioxidant activities, achieving 98.01% ABTS⁺· and 88.91% DPPH· radical scavenging rates at 1.2 mg/mL. Antibacterial tests showed moderate inhibitory effects against Staphylococcus aureus and strong effects against Escherichia coli , with maximum inhibition zones of 11.04 mm and 16.14 mm, respectively. Additionally, the flavonoids exhibited α-glucosidase inhibitory activity, suggesting potential antidiabetic properties.Liquid chromatography–mass spectrometry (LC-MS) analysis identified 29 flavonoid compounds, including rutin, quercetin, and isovitexin. These findings provide theoretical support for the functional application of Moringa flavonoids in natural antioxidants, antimicrobial agents, and blood glucose regulators.