Ultrasound-assisted aqueous two-phase extraction of synephrine, naringin, and neohesperidin from Citrus aurantium L. fruitlets

The ultrasound-assisted aqueous two-phase extraction (UA-ATPE) was first employed to develop an effective technique for simultaneous extraction and preliminary purification of synephrine, naringin, and neohesperidin from Citrus aurantium L. fruitlets. Five types of ethanol/salts of aqueous two-phase system (ATPS) were investigated and then the extraction conditions were further optimized using single-factor experiments and response surface methodology (RSM) via Box-Behnken Design (BBD). The optimum process parameters were concluded as follows: 20.60% (w/w) K₂CO₃, 27% (w/w) ethanol, solvent-to-material ratio of 45.17:1 (g:g), 120-mesh particle size of fruitlets powder, extraction temperature of 50 °C, extraction time of 30 min, and ultrasonic power of 80 W. Under these conditions, the extraction yields of synephrine, naringin, and neohesperidin were up to 11.17 mg/g, 7.39 mg/g, and 89.27 mg/g, respectively. The yield of neohesperidin extracted by the optimal UA-ATPE was over eight times higher than that extracted by the ultrasound-assisted extraction (UAE) using conventional solvents, and the total yield of target compounds was over twice higher while the impurity content in the extract was much lower. Therefore, UA-ATPE appeared to be a highly effective and promising approach for the extraction of synephrine, naringin, and neohesperidin from C. aurantium fruitlets.