Ultrasound extraction, quantification, and antioxidant activity of flavonoids from Aquilaria sinensis leaves

In this work, the ultrasound-assisted extraction (UAE) method was performed to obtain the total flavonoids (TF) from Aquilaria sinensis (A. sinensis) leaves, followed by optimization of the extraction factors by using a single-factor experiments combined with Box–Behnken response surface methodology to enhance the TF yield. Subsequently, the composition of the two representative flavonoids, mangiferin and genkwanin, were quantitatively determined by high-performance liquid chromatography (HPLC). Finally, the antioxidant activity of the TF was evaluated using an H₂O₂-induced oxidative stress model in intestinal porcine epithelial cells-jejunum (IPEC-J2) cells. The results demonstrated that under the optimized UAE conditions (70 % of ethanol concentration, liquid-to-material ratio at 40:1, 45 min of ultrasonic time, and 400 w of ultrasonic extraction power), the extraction rate of the TF reached 5.73 %, which was significantly higher than that achieved by conventional extraction. The HPLC analysis of mangiferin and genkwanin revealed well linearity and stability, with their content level to be 16.9 and 0.204 mg/g, respectively. Additionally, the TF extract significantly alleviated H₂O₂-induced cell death in IPEC-J2 cells by inhibiting the NF-kB/NLRP3/IL-18 signaling pathway. This study provides valuable information for the development and utilization of TF from A. sinensis leaves as a functional ingredient in feed and nutritional health products.