Optimization of Ethanol-Ammonium Sulfate Aqueous Two-Phase Assisted Ultrasound Extraction of Flavonoids from Loquat Leaves and Determination of Their Antibacterial Activity

枇杷叶中黄酮类物质的提取采用超声波辅助乙醇硫酸铵双水相体系，进行单因素和正交试验。结果发现，枇杷叶黄酮的更优工艺是超声辅助双水相提取。超声功率420 W，超声温度50℃，超声时间40 min，液料比25 mL/g，硫酸铵用量7 g，醇水比0.6为最佳工艺条件，黄酮类在此条件下浸出量为8.01 mg/g。在体外抑菌活性研究中，该提取物对絮状表皮癣菌表现出最强的抑制作用，其最低抑菌浓度和最小杀菌浓度均为0.0029 g/mL。This study optimized the extraction process of flavonoids from loquat leaves using an ethanol-ammonium sulfate aqueous two-phase system coupled with ultrasound-assisted extraction. Single-factor and orthogonal experiments were conducted to determine the optimal conditions. The results revealed that the superior extraction parameters were as follows: ultrasound power of 420 W, temperature of 50˚C, extraction time of 40 min, liquid-to-material ratio of 25 mL/g, ammonium sulfate dosage of 7 g, and ethanol-to-water ratio of 0.6. Under these conditions, the flavonoid yield reached 8.01 mg/g. In vitro antibacterial activity tests demonstrated that the extract exhibited the strongest inhibitory effect against Trichophyton mentagrophytes, with both the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) being 0.0029 g/mL.