Optimization of the flash-ultrasonic combined extraction process of Ligularia fischeri and evaluation of bioactivities

Ligularia fischeri is a perennial herb widely used in traditional medicine, largely due to its rich flavonoid content. This study employed a novel green extraction technique, namely flash-ultrasonic combined extraction, for extracting compounds from L. fischeri . The extraction process was optimized using Box - Behnken Design (BBD)-Response Surface Methodology (RSM) to maximize flavonoid yield. The optimal conditions were determined to be a material-to-liquid ratio of 1:30 g/mL, 73% ethanol, 73 s flash extraction, and 19.5 min ultrasonic treatment, resulting in a yield of 61.01 mg/g total flavonoids. The combined method outperformed individual flash or ultrasonic extraction, indicating a synergistic effect. The L. fischeri extract (LFE) inhibited the viability of A549, Caco2, and HepG2 cancer cells in a dose-dependent manner, with A549 cells being most sensitive. LFE also demonstrated broad-spectrum antibacterial activity, with the strongest inhibitory effect observed against Staphylococcus aureus . These results highlight the efficiency of the flash - ultrasonic combined extraction for obtaining flavonoid-rich extracts and underscore the potential of LFE as a natural source of anticancer, and antibacterial agents, supporting its application in natural therapeutics.